SOME NOTES FOR REASON AND ARGUMENT COURSE (BASED ON PART OF
MY DK BOOK)
STEPHEN LAW
TEXT BOX What is an argument? Outside of philosophy, the
word “argument” is used in a variety of ways. An argument in a bar may involve
little more than people hurling insults at each other. In philosophy, the word
tends to be used more specifically. Usually, when philosophers talk about an
argument, they are referring to a sequence of one or more premises and a conclusion. The
premises are supposed rationally to
support the conclusion.
Arguments can be simple. But they can also be highly
complex. Often, a philosophical book or treatise consists of one big argument
made up of a series of smaller ones, which may in turn involve further
subsidiary arguments, and so on. In order to assess the overall argument, you
need to check whether each of the component arguments works properly.
Caption. The detective Sherlock Holmes relied on his powers
of reason to uncover the truth. Reason, we suppose, has great truth-detecting powers.
Caption – shoes sticking out. It is reasonable to suppose
there is someone standing behind the curtain, because that is the best available explanation of what we
can observe – an example of inductive reasoning.
Caption – 5 peaches. The more peaches I observe with stones
in, the more reasonable it is for me to conclude the next peach will contain a stone – an example of enumerative
induction.
Reasoning (A head)
In Philosophy, we often want to construct a reasoned case for believing something,
or to spot where someone has made an unreasonable
move. In this chapter, we are going to look more closely at the use of reason.
We begin by asking what is reason, and what makes a belief reasonable?
Deductive reasoning (B heading)
Perhaps the most obvious way of showing that a claim is
reasonable is by producing a sound argument in its support.
Such an argument is an inference
involving one or more premises and a conclusion, where the premises are
supposed rationally to support the conclusion. Here is a simple example.
Tom is a human
All humans have a brain
Therefore: Tom has a brain
This is a deductive
argument. In a deductive argument, the premises are supposed logically to
entail the conclusion. When the premises entail the conclusion, we say the
argument is valid.
The above argument is valid. Necessarily, if the two premises are
true, then the conclusion is true. Someone who asserts the premises but denies
the conclusion is involved in a logical contradiction.
Of course,
even if a deductive argument is valid, its conclusion may not be true. Consider
the following example:
Elvis Presley is alive
Anything alive resides in Brazil
Therefore: Elvis Presley resides
in Brazil
This argument is valid. But its conclusion is false. In
order to confirm that the conclusion is true, we need to ensure two things – we
need to ensure both that the argument is valid and that its premises are true.
Inductive reasoning
(B heading)
Deductive argument is not the only legitimate form of
inference. There is also inductive
argument. In an inductive argument the premises do not, and are not intended,
logically to entail the conclusion. They are supposed merely to provide
rational support to the conclusion. Here is a classic example:
Peach number 1 contains a stone
Peach number 2 contains a stone
Peach number 3 contains a stone
{…}
Peach number 1000 contains a
stone
Therefore: all peaches contain
stones
This argument contains one thousand premises (I have not
bothered to them list all) and a conclusion. Obviously, the premises do not logically
entail the conclusion. There is no logical contradiction involved in claiming
that although the first one thousand peaches I observed contained stones, the
next one won’t. Still, despite not being deductively valid, we suppose
inductive arguments are able to provide good
grounds for beieving their conclusions are true. Surely, the more peaches I
observe that contain stones, the more reasonable it is for me to believe they all contain stones (unless, of course, I
happen to discover one without – that would immediately falsify the hypothesis that all peaches contain stones).
The above
argument is an example of enumerative
induction – we observe a number of Xs that are Y, and then generalize to the
conclusion that all Xs are Y (or that
the next X will be Y).
Enumerative induction is not the
only form of inductive reasoning. In an argument
to the best explanation, the existence of something may be posited as the
best available explanation of what has been observed, like so:
X is observed.
The existence of Y provides the
best available explanation of X
Therefore: Y exists.
Suppose I am a detective investigating the scene of a murder
that took place only moments ago. While studying the room, I notice a pair of
shoes poking out from under a twitching curtain. Under these circumstances, it
may well be reasonable for me to conclude that there is someone standing behind
the curtain. There’s no logical guarantee there is anyone there, of course –
perhaps the shoes are empty and the curtain is blown by the wind. Still, that
there is someone hiding behind the curtain may provide the best available
explanation of what I can observe. In which case, it is reasonable for me to conclude that there is someone standing there.
Inductive reasoning is
particularly important to the empirical sciences. Scientists construct theories
that are supposed to hold for all places and all times, including the distant
future and past. But they cannot themselves directly observe all times and
places. So they must rely on what they can observe in order to justify their
claims. It is inductive reasoning that allows them to do this.
For example, scientists may note
that every action they have observed has been accompanied by an equal and
opposite reaction, and then use enumerative induction to draw the conclusion
that all actions are accompanied by
equal and opposite reactions. Or they may observe certain experimental results,
note that the existence of a theoretical particle such as the electron provides
the best available explanation of those results, and so conclude that electrons
exist. That would be a scientific application of argument to the best
explanation.
Preserving truth (B heading)
You can see that cogent inductive and deductive arguments
have a truth-preserving quality to
them. If you feed true premises into a valid deductive argument, you are guaranteed to arrive at a true
conclusion. If you feed true premises into a sound inductive argument, you are likely to arrive at a true conclusion.
For those of us who like to believe what is true, this is a nice feature.
Notice that
if you are unwilling to accept the conclusion of an apparently cogent inductive
or deductive argument, the onus is on you to do at least one of two things. You
might fault the argument by showing that it is invalid (if a deductive
argument) or unsound (if inductive). Or you might try to show that one or more
of the premises is either false at least inadequately justified. Or you might
try to do both these things.
Other ways to be “reasonable”? (B heading)
A belief supported by a cogent argument may be reasonable.
But is that the only way in which
beliefs can qualify as reasonable? After all, if a belief is reasonable only if
it is inferred by means of a cogent argument from other reasonable beliefs,
they too will have to be inferred, and so on. You can see that a regress threatens here – in order to
show that even one of our beliefs is
reasonable, we will have to show that an infinite number are.
How might
we avoid this regress? One possibility would be to claim that certain beliefs
are non-inferentially justified.
Suppose I believe that there is an orange on the table in front of me for the
simple reason that I can see it
there. [NB LOUISE AND MAREK, MAKE PICTURE OF OBJECT ON TABLE AN ORANGE]. We
would ordinarily consider my belief reasonable despite the fact that I do not infer the presence of the orange – I
just directly observe it is there. True, it is possible I am mistaken about
there being an orange on the table (perhaps I am hallucinating or dreaming).
But surely, despite that possibility, my belief is still very reasonable
indeed.
So it seems
some beliefs can be reasonable despite not being inferred. In particular, my
belief might be reasonable because I myself am in a position directly to observe that it is true.
Text box: Justifying reason (B heading)
We believe that the use of inductive and deductive inference
is reasonable. Indeed, we believe these forms of reasoning are, in the case of
valid deductive arguments, guaranteed,
and in the case of sound inductive arguments, at least likely, to lead us to true conclusions, given that we start with
true premises.
But what, in turn, is the
justification for believing that these forms of reasoning are themselves
reliable roads to truth? If, in order to justify them, we need to construct a
cogent argument in their support,
then we will be using reason to justify
itself. But that, surely, is a circular justification and so no
justification at all. We can no more use reason to justify reason than we can
justify trusting a second-hand car salesman by pointing out that he himself
claims to be trustworthy.
But then how might reason be justified? One
possible solution would be to claim that the reliability of these various forms
of reasoning can be shown non-inferentially.
In the very simplest cases, that our forms of reasoning are at least likely to
lead us to true conclusions can just directly be seen.[186]
Reason as a filter (B heading)
One of the ways in which we can apply reason is as a filter. You might think of your mind as
a basket towards into which all sorts of belief might tumble – from sensible
ones such as that the Earth is round to ridiculous one such as that Elvis lives
or that the Belgians are the secret rulers of the universe. By applying your powers
of reason to these various beliefs – by subjecting them to critical scrutiny –
you can filter them, allowing through only those beliefs that have at least a
good chance of being true.
How
demanding should this filter be? Descartes famously decided to subject all his
beliefs to critical scrutiny, allowing through the filter only those that could
not be doubted. Of course, few if any beliefs are indubitable. A less
stringent, but still very robust, requirement would be to allow through only
those beliefs that have a high probability of being true. [155]
Caption: object on a table (must be an orange!). Under
normal circumstances, it’s surely reasonable for you to believe there is an
orange on the table in front of you if you can see that the orange there.
caption: filter. Reason can be used as a filter. Pass your
beliefs through the filter of reason and there’s a good chance that many of
them will be true.
FALLACIES (A
HEADING)
A fallacy is an error
in reasoning. Often, the error is not obvious, with the result that people
are easily duped by the argument. There is a whole series of more-or-less
plausible looking arguments that turn out, on closer inspection, to be
fallacious. This section looks at nine classic examples.
Sometimes arguments are fallacious because the conclusion is not supported by the premises. In a fallacious deductive argument, the premises may not
logically entail the conclusion. In a fallacious inductive argument, the premises may not inductively support the
conclusion. However, sometimes the logica of the argument is sound, but one of the premises is false (this is true opf false dilemma, for example, which has the form P or Q. Not P, Therefore Q. The premise P or Q is actually false, there are other options - see below). Learning to spot fallacies is an important philosophical skill. In
fact some of the best-known philosophical arguments involve fairly
straightforward fallacies. We will shortly see some examples.
Slippery slope
fallacy (B HEADING)
We are often warned against stepping onto “slippery slopes”
– dangerously greasy slides that lead down to where the really bad stuff lies. Unfortunately, these warnings often
over-estimate the risk of the “slide”. Unless the proponent of a “slippery
slope” argument can provide good grounds for supposing such a slide is
inevitable, or even just likely, their argument is fallacious.
Here is a simple example. Suppose
I ask you to lend me one pound. Your friend warns you against lending me the
money on the following grounds:
If
you lend Stephen one pound today, tomorrow it will be two pounds, then ten
pounds. Pretty soon he will owe you thousands!
Obviously, if you lend me one pound today, you can still
easily refuse to lend me two pounds tomorrow or ten next week. The slide from
owing one pound to owing thousands is not inevitable. In fact it is not even
likely. As it stands, this is a fallacious use of the “slippery slope”.
It is
possible this argument might be salvaged. Perhaps your friend can show both
that I am an inveterate borrower and that you find it hard to say “no” once you
have said “yes”. In that case, their warning not to lend me even one pound
begins to look more credible. But your friend does need to be able to provide
these additional grounds. Without them, the warning is hollow.
But what about the following
argument? Does it commit the “slippery slope” fallacy?
If
we allow a couple to select the sex of their baby today, tomorrow we will have
to allow selection for eye and hair colour. Pretty soon, we will have to permit
“designer babies.”
Yes, it does, if no justification is provided for supposing
that we cannot or will not simply stop at some point along the “slide” from
selection of sex to full-blown “designer babies”.
Slippery
slope arguments often crop up in connection with the legalizing of things, such as recreational drugs, euthanasia,
genetic engineering, and so on.
Suggest that the recreational use
of marijuana should be legalized, for example, and many will warn that this
would be the first step onto a slippery slope that will quickly lead us on to
legalizing heroin and crack cocaine. Perhaps such a slide is likely. But the
onus is on the proponent of this argument to show that. If they cannot show it,
they too have committed the slippery slope fallacy.
There are degrees of slipperiness,
of course. Even where there is some
tendency for a slide to occur, a slip might still easily be avoided. Slippery
slope arguments often obscure the fact that there may be effective ways of
halting any skid.
Other
phrases that may indicate the use of a slippery slope argument are “thin end of
the wedge”, “opening the floodgates” and “give them an inch and they’ll take a
mile”. In each case, the result of even a small move in a particular direction
is often just assumed to be a
dangerous and probably unstoppable slide. Where that is the case, the argument
is fallacious.
CAPTIONS (20-40 words each)
1 FRANKENSTEIN’S MONSTER It is often said that if we allow
the use of genetic engineering in some
cases, we won’t then be able to stop the slide into allowing other, more
dubious, Frankenstein-type applications.
2 GROWING PILES OF COINS. An obviously fallacious slippery
slope argument: “Lend you a pound? If I lend you one pound now, it will be two
pounds tomorrow and a ten pounds next week. It won’t be long before you owe me
thousands!”
3 SKIER. In a slippery slope argument, it’s claimed that if
we take even one step onto the slope,
we will inevitably end up sliding down to the bottom, where the really bad stuff lies.
The Gambler’s Fallacy
(B heading)
CAPTION racehorses. “Black beauty wins half her races. She’s
running twice today and she didn’t win the first time so she must win now!” This is a classic example
of the gambler’s fallacy.
TEXT BOX The lottery fallacy. Another common,
gambling-related reasoning error is the
lottery fallacy. People sometimes conclude that because a particular event
would otherwise be very improbable, the fact that it did occur makes it
probable that someone or something must have somehow deliberately produced it.
For
example, suppose I buy one of a million lottery tickets. My ticket wins. That
leads me to conclude that someone or something must have arranged for me to
win. I conclude I must have a guardian angel who organized the windfall for me.
But of
course, this is faulty reasoning. I have no justification at all for supposing
someone fixed the lottery in my favour. After all, whoever won would have been
no less likely to win. Given there was bound to be a winner, there was bound to be an extremely unlikely
event. There are no grounds for believing that the fact that the
one-in-a-million winner is me is anything more than an amazing coincidence.
MAIN TEXT
Here is a simple example of the gambler’s fallacy.
Jenny: Still buying those scratch cards?
John: Yes. I’ve been playing regularly for three years and I haven’t
won a thing.
Jenny: So why do you bother?
John: Well, as I haven’t won anything yet, I must be due a win soon!
In this version of the fallacy, someone takes the
probability of an event A happening
over a period of time, notices that, over the first part of that period, the
actual incidence of A is much lower
than what is probable, and concludes that A
is therefore much more probable over
the rest of the period. They predict a short-term increase in the probability
of A to “even things up” over the
longer term.
Here is
another example: someone rolls a dice 30 times and happens not to get a single
six. They conclude they are now much more likely to get a six on the next roll.
The truth, of course, is that the probability of their getting a six still
remains exactly the same – one-in-six.
The fallacy can work the other
way too: people sometimes assume that a higher than expected incidence of A must result in a short term lowering
in the probability of A to “even
things up”, as in this case.
Ruth: Doing the lottery again this week?
John: Yes. What numbers are you going to pick?
Ruth: Well, the numbers 6, 9 and 23 have
come up a lot recently, so I’ll be avoiding them - they aren’t likely to come
up again for a while.
The gambler’s fallacy is common. Stand next to a lottery outlet for a little
while and it won’t be long before you hear someone say they are “due” a win,
that they won’t be silly enough to pick the same numbers that won last week,
and so on.
The fact is it makes no
difference what numbers have come up before. Each week the probability of any
particular sequence of numbers winning the UK lottery is always exactly the
same: about 14 million to one.
Appeal to Authority (B heading)
CAPTION: Stethoscope. It is worth trusting a doctor’s medical advice, because a doctor is a recognised authority on medicine. That doesn’t make a doctor an authority on car maintenance, of course.
CAPTION: advertising a or b. The advertising industry often uses celebrities to endorse products, despite the fact that the celebrities in question have no relevant expertise.
MAIN TEXT
We are often justified in believing something because an
authority on the subject tells us that it is true. If a car mechanic advises
you to put water and not oil in your car radiator, I would follow her advice.
But
sometimes such “appeals to authority” are suspect. Here are four examples:
I believe that Supawhite toothpaste cleans whiter than any other brand.
Why?
Because scientists working for the Supawhite Corporation tell me so.
I am going to find my perfect partner soon
Why are you so sure?
I consulted a fortune cookie
I believe homeopathy can cure serious diseases
Why do you believe that?
Because Dr Smedley told me
Is Dr Smedley a medical expert?
No, he’s a professor of mathematics
Camel dung face packs are an effective beauty treatment
How do you know?
Joe Sopwith, actor and pop star, advertizes them on TV
In the first example, the authority in question may be
untrustworthy. To what extent can scientists working for a particular company
be trusted to give unbiased advice about its products?
In the second and last
examples, the “authorities” in question are dubious. What grounds do we have
for supposing that fortune cookies are reliable source of information about the
future? And why is a celebrity like Joe Sopwith to be any better informed about
the effectiveness of camel dung face packs than anyone else?
In the third example, it is
true that the person consulted really is an authority. Unfortunately, they are
not an authority in the relevant area. Dr Smedley’s area of expertise is maths,
not medicine. There is no reason to suppose that Dr Smedley’s views about
homeopathy are any better informed than are yours or mine.
The moral is that, when appealing to an “authority”, you need to check several things, including:
Is the
person in question really an authority?
Are they an
authority on the relevant subject?
Can we be
confident this authority is not biased?
Is the view of this authority consistent
with that of the majority of competent authorities in this area?
If the answer to any of these questions is “no”, you would be wise not to place your trust in the authority in question.
False Dilemma (B heading)
Caption: road sign showing fork in road. In an example of false dilemma, we are presented with just two options when there are, in truth, other alternatives.
Caption: advert products a and b: Salespeople sometimes use false dilemma: “Your choice is to either buy our product A, or inferior product B. So you just have to buy A!” There may be other alternatives, such as buying neither.
MAIN TEXT
It is common to argue like this:
Either A or B
Not A
Therefore B
This is often a perfectly acceptable form of argument, as in
this case:
Either Peter has a pilot’s license or else Peter is not permitted to pilot a plane.
John has not got a pilot’s license.
Therefore, John is not permitted to pilot a plane.
This argument, on the other hand, is not acceptable:
Either I am a giraffe or I am a hippo
I am not a hippo
Therefore, I am a giraffe
What is the problem with the second argument? The first premise presents us with two options both of which are false. In the fallacy of false dilemma we are similarly presented with just two options when there are more. We are told that the only alternatives are A or B. The possibility of choosing C is entirely ignored.
Politicians sometimes use false dilemma to try to force us into making a decision we do not in fact have to make. For example, they may say:
Either we invade Zenda or we allow Zenda to take over the world.
We don’t want Zenda to take over the world, do we?
So we should invade Zenda.
It may not be true that Zenda is planning to take over the
world. If so, the choice with which we are presented is a false one. But notice
that, even if Zenda is intent on
world domination, there may be other effective ways of dealing with such rogue
states. Invasion is unlikely to be the only option.
Politicians are not the only
culprits when it comes to false dilemma. Customers are often maneuvered into making bad decisions by a
salesperson’s use of false dilemma:
You can either buy Supawhite toothpaste for a pearly-white smile, or
you can make do with yellow teeth.
You don’t want yellow teeth do you?
So you have to buy Supawhite!
No doubt some other toothpastes that are just as effective - perhaps even more effective - than Supawhite. These alternatives have been conveniently airbrushed out by the salesperson – leaving you with a false dilemma.
The moral is that, when you seem forced to choose between two alternatives, it is often worth checking whether they really are the only available options. Are you being railroaded by false dilemma?
The Post Hoc Fallacy (B heading)
Here is a classic example of the post hoc fallacy:
I had been worrying
about my driving test. So John bought me a rabbit’s for luck. I took the foot
and passed with flying colours. So you see, the rabbit’s foot worked! I am
going to take it to all my other exams to help me pass them too.
In the post hoc fallacy, someone concludes that because one event happened
after another, the first is likely to be the cause of the second.
Obviously,
the mere fact that one thing happened after another does not normally give us
much reason to suppose that the two events are causally connected. Suppose I
turn on my toaster. Shortly afterwards a volcano erupts on Mars. Did my turning
the toaster on cause the Martian eruption? Of course not. There is no reason at
all to suppose these two events are causally connected.
Here is another example:
John’s psychic healer gave him a twig to chew on. And he got better! So
you see, chewing on that twig really did make him well. I am going to start
visiting the same psychic healer myself!
Again, the fact that one thing happened after another is
taken to be good evidence of a causal connection.
Of course,
there may be a causal connection
between two consecutive events. Perhaps
John’s twig-chewing really did make him better. Perhaps rabbit feet can
magically help us pass exams. The point is that a single “one off” observation
does not remotely justify these
claims.
The moral is: don’t leap to conclusions. Noticing that
one event occurs immediately after another might give us grounds for
investigating whether the events are causally related. But it does not, by
itself, make it rational to believe there is any such a connection.
Superstitious people tend to be particularly prone to the post hoc fallacy. But almost all of us fall for this fallacy on occasion. So beware.
Affirming the consequent: Joe’s DIY mistake
TEXT BOX. Modus
Ponens. Arguments of this type:
If A then B
A
Therefore B
are valid. Here’s an example:
If the power is off, then the
light won’t come on
The power is off
Therefore the light won’t come on
This argument form is called Modus Ponens.
In a conditional of the form: If A then B, A is called the antecedent and B the consequent. In the
fallacy of affirming the consequent, the second premise of the argument affirms
the consequent (rather than the antecedent, as in Modus Ponens), like so:
If A then B
B
Therefore A
Hence the fallacy is called affirming the consequent.
CAPTION light bulb (make the image of a lightbulb that is
off): Joe reasons like so: If the power is off the light won’t come on; the
light won’t come on, so the power is off. Joe gets a nasty shock as a result of
this fallacious reasoning.
MAIN TEXT
Joe is busy rewiring his house. He is about to touch one
of the wires when he suddenly wonders whether he remembered to turn off the
power. He looks up, and sees that, though the light is switched on, it remains
off. So Joe reasons like this: If the power is off, the light won’t come on.
But the light won’t come on. So the power is off. Joe touches the wire and gets
a nasty shock. Why?
Joe has just
been electrocuted by a bit of bad reasoning. He reasoned like this:
If the power is off, the light
won’t come on
The light won’t come on
Therefore the power is off
Joe’s argument has the following form:
If A then B
B
Therefore A
Arguments of this form aren’t valid. True, the light isn’t
on. But perhaps that is because it has a faulty bulb. It doesn’t follow that the power is off.
Joe’s argument resembles a valid
form of argument called Modus Ponens, which is why he got confused, with nasty
consequences. This error is a very common. It’s called the fallacy of affirming the consequent. A recent study indicates that over two thirds of people without any
training in informal logic regularly commit this fallacy. In all
probability, you sometimes make the
same sort of mistake as Joe. To avoid this type of faulty reasoning, keep an
eye out for “If …then….” claims and make sure the logic of the argument runs in
the right direction. That way you won’t end up fried like Joe.
Genetic fallacy
(B heading)
QUOTE: Oak trees come
from acorns. Acorns are small and shiny. Therefore oak trees are small and
shiny
CAPTION: An example of the genetic fallacy: “If the egg has
a hard shell, and the chicken came from the egg, the chicken must have a hard
shell too.”
MAIN TEXT
In the genetic fallacy, it is argued that if one thing B has
its origin in another thing A, any properties possessed by A are also likely to
be possessed by B. Here are two simple examples:
Eggs have hard shells
Chickens come from eggs
So chickens have hard shells too
Oak trees come from acorns
Acorns are small and shiny
Therefore oak trees are small and shiny
The philosopher Friedrich Nietzsche stands accused of
committing the genetic fallacy. Nietzsche argues that modern Christian morality
has its roots in the “slave morality” of ancient Rome’s slaves, a morality born
of the resentment the slaves felt towards their masters (the slaves effectively
reversed what their masters believed was of value, making weakness a strength,
strength a weakness, and so on).
Suppose
Nietzsche is right about the genesis
of Christian morality – that it originated in feelings of resentment. Does that
discredit Christian morality?
Nietzsche seems to assume that
pointing out a defect in the origin of a thing discredits the thing itself. But
that is usually fallacious reasoning. Here are two more examples:
Fred’s father was a Nazi
So Fred must be a Nazi himself
Democracy in Zenda was born of a violent and bloody struggle
So Zenda’s democracy must be a bad thing
The fallacy is also committed when it is assumed that if
something had its origin in something good, that thing must itself be good. For
example:
Hitler’s parents were loving and kind
So Hitler must have been loving and kind
The Klingons’ terrorist activity is the result of a legitimate
grievance
Therefore the terrorist activity must itself be legitimate
Sometimes it is
possible to draw such an inference, but only rarely. For example, this
inference:
John is reliable source of information
This claim came from John
Therefore
this claim is reliable
is reasonable. I will
leave you to figure out why.
Leibniz’s Law and the
masked man fallacy (b heading)
P202 CAPTION Is this the same mountain viewed from two
different angles, or two different mountains? We might try to show that it is not the same mountain by applying
Leibniz’s law.
P203 CAPTION. (Masked burglar) The masked man fallacy: “I
believe the masked man robbed the bank. I don’t believe my father robbed the
bank. Therefore my father is not the masked man.”
P203 TEXT BOX (120 words) In his Meditations, Descartes argues that mind and body are distinct
substances capable of independent existence. In order to draw that conclusion,
Descartes applies Leibniz’s law. One of Descartes’ arguments appears to be a
version of the argument from doubt, discussed here. Another argument concerns
spatial extension. Descartes points out that physical substances are spatially
extended. His mind, on the other hand, appears not to be spatially extended. Descartes then applies Leibniz’s law
something like so:
My mind is not spatially extended
My body is spatially extended
Therefore, my mind and my body
are not identical
What, if anything, is wrong with this application of Leibniz’s law?
P204 image: cary grant (preferably in Hitchcock’s North by
NorthWest). Caption: Cary Grant is identical with Archibald Leach. They are one
and the same person.
P204 quote: “Identical objects must share all the same
properties.” Leibniz’s law.
MAIN TEXT Philosophers and scientists often consider identity claims. Let’s begin with a
couple of scientific examples.
One important ancient
astronomical discovery was that Hesperus, the evening star, is identical with
Phosphorus, the morning star. What appeared to be two distinct heavenly objects
turned out to be one and the same object
– the planet we now call “Venus”.
Scientists also claim that
certain properties are identical. For
example, it is claimed that heat is molecular motion. They are one and the same property.
We also make identity claims in everyday life. You
might discover, for example, that Cary Grant and Archibald Leach are one and
the same person, or that Chomolunga and Mount Everest are one and the same
mountain.
The philosopher Leibniz noted
that if two objects are identical, then any
property possessed by one object will also be possessed by the other. Take
Mount Everest and Chomolunga, for example. If Mount Everest has the property of
being 29,000 feet high, then Chomolunga will have that property too. The
principle that identical objects must share the same properties is often
referred to as Leibniz’s law.
Leibniz’s law provides us with a useful tool.
Suppose an explorer discovers what he believes to be two separate mountains.
But then, on returning home from his travels, he wonders whether it wasn’t just
the same mountain seen from two different angles. How might the explorer
establish that he is the discoverer of two mountains, and not just one?
The
explorer might apply Leibniz’s law. If identical objects share all the same
properties, then all the explorer has to do is find a property possessed by one
mountain not possessed by the other. That would show that the number of
mountains he discovered is two, not one.
Suppose, for example, that the
explorer measured and recorded the height of both mountains. He discovered that
while mountain A was 5,000 metres high, mountain B was much higher. Then the
explorer can apply Leibniz’s law like so:
Mountain A is 5,000 metres high
Mountain B is not 5,000 metres
high
Therefore mountain A is not
identical with mountain B
This is a cogent argument. The mountains differ in at least
one of their properties. So they cannot be identical.
Philosophers also consider identity claims. And they also
regularly press Leibniz’s law into service.
Take substance dualism, for example.
Substance dualists deny that mind and body are identical. According to
substance dualists, mind and body are distinct substances capable of
independent existence.
How might a
substance dualist use Leibniz’s law to make their case? If the dualist can find
a property possessed by the mind that is not also possessed by the body, or
vice verse, that would show that mind and body are not identical.
Is there such a property?
Here is one suggestion. I can
doubt whether my body exists. I can even entertain the thought that there may
not be a physical world at all. In his Meditations,
Descartes famously raises the hypothesis that there might be a powerful evil
demon intent on deceiving him into believing the physical world exists when it
is in truth just an illusion. The demon causes his mind to have experiences
which, while they seem to be of
trees, houses and even his own body,
are wholly deceptive. I do not say that it is at all likely such a demon
exists, of course. But it does at least appear to be a possibility. I can, in a
similar way, at least entertain the doubt that my body exists.
On the
other hand, it seems I cannot doubt that I
exist. By trying to doubt that I exist, I think, but by thinking I immediately
demonstrate that I do exist. As Descartes puts it: “I think, therefore I am”.
But then it
seems we have discovered a property that my body possesses that I myself lack.
My body possesses the property of being something
I doubt exists. My mind lacks this property. But then why can’t we apply
Leibniz’s law like so?
My body possesses the property of
being something I doubt exists
My mind does not possess the
property of being something I doubt
exists
Therefore: my mind is not
identical with my body
This is a version of what is often called the argument from doubt. Both premises of
the argument are true. And, by Leibniz’s law, the conclusion seems to follow.
So have we succeeded in proving my mind is not my body?
No. The argument from doubt (or
at least this version of it) commits a notorious fallacy called the masked man fallacy. Suppose I
witness a robbery. I see a masked man rob a bank. Later, detectives tell me
their chief suspect is my father. I am horrified. Surely my father would never
do such a thing. So I attempt to prove my father’s innocence in the following
way. I point out that the masked man has a property my father lacks. The masked
man is someone I believe robbed the bank. My father is not someone I believe
robbed the bank. But then, by Leibniz’s law, it seems the masked man cannot be
my father:
The masked man is someone I
believe robbed the bank
My father is not someone I
believe robbed the bank
Therefore: the masked man is not
identical with my father
Both premises of this argument are true. Yet the conclusion
does not follow. Clearly, my father could still turn out to be the masked
man. There is something wrong with this argument. But what?
The answer
is that Leibniz’s law does not apply to all
properties. It works for properties such as being
5,0000 metres high. It does not work for properties such as being someone I believe robbed the bank.
More generally, this form of argument does not work whenever the property in
question involves someone’s psychological
attitude towards a thing.
For example, in the masked man
case, I try to show that my father and the masked man are distinct by pointing
out that I have an attitude towards
one that I don’t have towards the other: I believe one robbed the bank but not
the other. But such attitudes are incapable of revealing whether or not the
items in question really are distinct. Here are two more examples:
Cary Grant is someone Tom
believes starred in in “North by North-West”
Archilbald Leach is not someone
Tom believes starred in “North by North-West”
Therefore Cary Grant is not Archibald
Leach
Alcohol is widely known to
intoxicate
C2H6O is
not widely known to intoxicate
Therefore alcohol is not C2H6O
Both these arguments have false conclusions despite having
true premises. The problem, again, is that what someone may know or believe or
recognise about one thing but not another is not the sort of property one can
use to establish that they are not one and the same thing. Both arguments
commit the masked man fallacy. So does the above version of the argument from
doubt outlined above.
“It’s true-for-me!” -
The Relativist fallacy (B heading)
CAPTION (Wichitty grubs.) May be some truths are relative. For example, perhaps the claim that
wichitty grubs are delicious is true
for some Australian aboriginals, but false for most Westerners.
CAPTION polygamy. Some believe the claim that polygamy is
wrong is true relative to mainstream Western culture but is false for other
cultures. This truth is also alleged to be relative.
MAIN TEXT
Jane: Belief in fairies is patently false. There’s no evidence to
suggest that fairies exist, and plenty of evidence that don’t. So it’s
ridiculous for you to believe in them.
Joe: Well, that fairies exist may not be
true for you. But it is true for me!
You may have come across this
retort yourself. Perhaps you have just made a very good case for supposing it’s
false that there is a community of goblins living in your friend’s biscuit
barrel, but then your goblin-fixated friend hits you with “Well, it’s true for me!”
What is “It’s true for me” supposed to mean, exactly?
Presumably, Joe means more than that Jane believes one thing about fairies
while he believes another. After all, even Jane can agree about that.
Perhaps what Joe is suggesting is that truth of the claim fairies exist is relative. There’s no objective truth about fairies – the truth is
simply whatever each of us believes it to be. Of course, what is believed does
vary from one person to the next. But can truth
vary in the same way?
One thing that can confuse here is an unacknowledged slide from what is true about what a person believes to the truth of what they believe. Yes, it may be true that I believe Paris is the capital of Germany. It doesn’t follow that my belief that Paris is the capital of Germany is true.
After all, if truth were relative in that way, I could make any claim true just by believing it. That would be convenient. Suppose I want to be able to fly. I can make it true that I can fly just by believing that I can. But of course the truth about whether or not I can fly, or whether or not fairies exist, is not relative in this way. If Joe is claiming otherwise, he is simply mistaken.
Still,
perhaps the truth of some claims is
relative. Take the truth of claims about whether or not things are delicious. Perhaps the claim wichitti grubs are delicious is true for
some aboriginal Australians but false for most Westerners. But it’s hardly
plausible that the truth of all
claims is relative in this way.
Someone
commits the relativist fallacy when they say “That may be false for you, but
it’s true for me” without providing
any grounds for supposing that the truth in question is indeed relative.
P206
THINKING TOOLS (A
HEADING)
Thinking philosophically is a skill, and, like most skills,
the more you practice, the better you get. This section introduces a few of the
philosophers tricks of the trade – tools which, once mastered, can be applied
in many different areas of philosophy. There are many such tools – what follows
is merely a small sample.
Most of the
thinking tools listed in this section warn against a common sort of mistake or
error. These include:
- Beware explanations that are really circular, generating a regress.
- Beware category mistakes – wrongly assuming that the sort of thing that can be said of one category of thing can also sensibly be said of another.
- Beware being seduced in by pseudo-profundity.
Also included is an outline of a particular approach to
answering a certain philosophical questions – an approach known as the method
of counter-examples. Those new to philosophy are often confused by the method,
which is why it receives its own explanation here.
[161]
Spotting a regress (B
heading)
CAPTION: “Everything has a cause. Therefore the universe has
a cause. Therefore God must exist as the cause of the universe.” But if
everything has a cause, what is the caus of God?
P207. CAPTION. Homunculi. If the behaviour of people is
explained by the actions of little people running round inside them, then do
these little people have even littler people running round inside them?
CAPTION. The Hindu myth of the Earth held up by an elephant
held up by a turtle. What holds up the turtle?
QUOTE (Hume, already supplied)
INTRODUCTION Vicious regresses are not uncommon in
philosophy. Philosophers often seek to explain things. Unfortunately, their
explanations sometimes turn out to be circular. They merely take for granted
what they are really supposed to be explaining. They simply postpone the
question, rather than really answer it. Where that is the case, a regress
looms. Spotting where an explanation generates a regress is an important
philosophical skill.
MAIN TEXT
Things fall when not supported. Take the sheet of paper on
which I am writing. It doesn’t fall because it is supported by a table. Why
doesn’t the table fall? Because it’s supported by the Earth. So why doesn’t the
Earth fall? Perhaps it was this question that led some ancient Hindu thinkers
to suppose that the Earth too must be supported. They concluded that the Earth
sits on the back of an enormous elephant. But of course this merely raises a
further question: what holds up the elephant? These Hindu thinkers had an
answer for that question too – the elephant is supported by a turtle. But then
what holds up the turtle?
You can see that a regress looms here. Even if we introduce
a giant squirrel to support the turtle, and a giant panda to support the
squirrel, and so on, we will never really succeed in explaining why everything
doesn’t fall. At each step we merely postpone that mystery.
Of course, we can avoid this
regress by insisting that one particular animal is the exception to the rule that everything falls if not supported. The
Hindus made the turtle the exception to the rule. It is the one thing that
requires no further support.
But if we are going to introduce an exception to
the rule, why go so far as the turtle? Why not just make the Earth the
exception to the rule instead. But then what justification have we for
introducing any of these cosmic beasts? The answer, it seems, is none at all.
Similar regress problems often
crop up in philosophy. Take this simple argument for the existence of God.
Everything has a cause. But then
what is the cause of the universe? It seems God must exist as the cause of the
universe.
You can see straightway that a regress threatens here, too.
The first premise says everything has
a cause. But if everything has a cause, so does God. It seems we will need to
introduce a second God as the cause of the first, a third God as the cause of
the second, and so on.
Of course, just as the ancient Hindus
made the turtle the exception to the rule that everything falls if unsupported,
we might insist that God is the exception to the rule that everything has a
cause. But then why not make the universe the exception to the rule, instead?
We have not, as yet, been given any
more reason to suppose God exists than we have to suppose there exists a giant
turtle.
Pseudo-profundity
(B HEADING)
INTRODUCTION Around the globe, audiences sit at the feet of
marketing experts, life-style consultants, mystics, cult-leaders and other
“gurus” waiting for the next deep and profound insight. Audiences often pay a
great deal of money to hear these words of wisdom. So how do these elevated
individuals come by their penetrating insights? What is the secret of their
profundity? Unfortunately, in some cases, the audience is duped by the dark
arts of pseudo-profundity.
CAPTION. Many marketing, religious and lifestyle “gurus” do
have genuine insights to offer. But not all. Unfortunately, some are charlatans
who offer little more than pseudo-profundity.
TEXT BOX. ORWELL AND THE ART OF CONTRADICTION. Another
secret of pseudo-profundity is to pick two words that have opposite or
incompatible meanings, and combine them cryptically, like so:
Sanity is just another kind of
madness
Life is a often a form of death
The ordinary is extraordinary
Try it for yourself. You’ll soon
start sounding deep. In George Orwell’s novel Nineteen-Eighty Four, the three slogans of the Party are all
examples of this sort of pseudo-profundity:
War is peace
Freedom is slavery
Ignorance is strength
A particularly useful feature of these remarks is that they
make your audience do all the work for you. “Freedom is a kind of slavery” for
example, is interpretable in all sorts of ways that probably won’t even have
occurred to you. Just sit back, adopt a sage-like expression, and let your
audience figure out what you mean.
None of
this is to say that such cryptic remarks can’t be profound, of course. But
given the ease with which they are generated, it’s wise not to be too easily
impressed.
CAPTION 2 (FENG SHUI) 20-40 words Feng-shui offers
seemingly-profound insights into how we should arrange our living spaces. But
to what extent is feng-shui guilty of pseudo-profundity?
MAIN TEXT (DPS) Actually, the art of sounding profound is
fairly easily mastered. You too can make deep- and meaningful-sounding
pronouncements if you are prepared to follow a few simple rules.
First, try stating the incredibly obvious. Only do it v-e-r-y
s-l-o-w-l-y, with a sort of knowing nod. This works particularly well if your
remark has something to do with one of the big themes of life, love, death and
money. Here are some examples:
Death comes
to us all
We all want
to be loved
Money is
used to buy things
Try it yourself. If you state the obvious with sufficient
gravitas, following up with a pregnant pause, you may soon find others start to
nod in agreement, perhaps muttering “How true that is”.
Now that you have warmed up,
let’s move on to a different technique – the use of jargon. A few big, not fully understood words can easily enhance
the illusion of profundity. All that’s required is a little imagination.
To begin with, try making up some
words that have similar meanings to certain familiar terms, but that differ
from them in some subtle and never-fully-explained way. For example, don’t talk
about people being happy or sad, but about people having “positive or negative
attitudinal orientations”. That sounds far
more impressive and scientific-sounding, doesn’t it?
Now try translating some dull
truisms into your newly invented language. For, example, the obvious fact that
happy people tend to make other people happier can be expressed as “positive
attitudinal orientations have high transferability”.
Also, whether you are a business
guru, cult-leader or a mystic, it always helps to talk of “energies” and
“balances”. This makes it sound as if you have discovered some deep mechanism
or power that could potentially be harnessed and used by others. That will make
it much easier to convince people that if they don’t buy into your advice, they
will really be missing out. For example, publish an article entitled
“Harnessing positive attitudinal energies within the retail environment”, and
Lo! another modern business guru is born.
Finally, if
someone does get up the courage to ask exactly what a “positive attitudinal
energy” is, you can always give a definition using other bits of your
newly-invented jargon, leaving your questioner none the wiser. If all your
jargon is defined using other jargon, no one will ever be able to figure out
exactly what you mean (though your devotees may think they know). And the fact that buried within your
pseudo-profundities are one or true truisms will give your audience the
impression that you must really be on to something,
even if they don’t quite understand
what it is. So they will be eager to hear more.
Unfortunately,
some cult-leaders, business gurus, mystics, life-style consultants, therapists
- and even some philosophers – make use of these techniques to generate the
illusion that they possess deep and penetrating insights. Now you can see how
easy it is to generate pseudo-profundities of your own, I’m sure you will be
rather less impressed the next time some self-styled “guru” suggests that your
attitudinal energies need balancing.
Method of
Counter-examples (B heading)
P210
CAPTION; (soldiers), Socrates often asks the question “What
is X?” of those who we might assume are best placed to know what X is. For
example, he asks the Athenian general Laches what courage is.
Quote “What is justice?” Socrates.
INTRO. Philosophers often ask questions of the form “What is
X?” Outside of philosophy, these questions are rarely asked. We assume we can answer them quite easily.
Until we try. In fact they are notoriously difficult to answer. One of the most
popular approaches to answering them is known as the method of counter-examples.
MAIN TEXT
You’ll find numerous
examples of such “What is X?” questions in the dialogues of Plato. In the
dialogues, Plato has Socrates ask the citizens of Athens such questions as
“What is justice?”, “What is beauty?” and so on. The Athenians usually think
they know the answers. They offer definitions that, at first sight, look very
plausible. Unfortunately, Socrates is able quickly to reveal the inadequacy of
their definitions. One way in which he does this is by employing the method of
counter-examples.
To explain the method, let’s
begin by applying it to a more mundane example. Suppose we ask “What is a
chair?” Most of us think we know perfectly well what a chair is. Isn’t this a
straightforward question, easily answered?
So let’s try to answer it.
Suppose we begin with:
A chair is an object built to be sat on.
This sounds plausible. Except that, with a little ingenuity,
it is possible to think of counter-examples. A wooden bench is built to be sat
on. But it is not, strictly speaking, a chair. Or suppose you discover a large
chair-shaped boulder that turns out to be perfect for sitting on. You install
it in your garden as a piece of garden furniture – a chair. The boulder is now
a chair. Yet this boulder, while now a chair, was not, strictly speaking, built to be sat on.
Faced with
these counter-examples to our definition, we might attempt to refine it.
Perhaps we might try this:
A chair is an object used for just one
person to sit on.
This definition gets round our first two counter examples. A
bench no longer qualifies as a chair, because a bench is used to seat more than
one person. And by switching from “built to be sat on” to “used for sitting
on”, our boulder-chair does now qualify as a chair.
Still,
perhaps we can think of counter-examples to this new definition. A bicycle
saddles is used for just one person to sit on. But a bicycle saddle is not a
chair. To deal with this counter-example, we might refine our definition still
further, like so:
A chair is an object with legs that is used
for just one person to sit on.
This definition rules out bicycle saddles. For bicycle
saddles don’t have legs. Unfortunately it also rules out our boulder-chair,
which does not have legs. It rules out inflatable chairs, too.
In order to
deal with these new counter-examples, we might try to refine our definition
still more. But you can begin to see how difficult it can be to provide a watertight
definition of even an object as straightforward and familiar as a chair.
Two sorts of
counter-example (C heading)
In trying to answer the question “What is a chair?” we have
been employing the method of counter-examples. A definition of X is offered.
One or more counter-examples to the definition are produced. The definition is
then refined in response to these counter-examples. But then more
counter-examples are offered. And so on, until we arrive at a satisfactory
definition.
Notice that
counter-examples may be of one of two sorts:
- We may think up possible examples which, though they do fit the definition of X, are not examples of X. Or,
- We may think up possible examples which, though they do not fit the definition of X, are examples of X.
The first sort of counter-example shows that fitting the
suggested definition is not sufficient
to qualify something as an X. The second sort of counter-example shows that
fitting the suggested definition is not necessary
if something is to qualify as an X.
In the
chair example we produced counter-examples of both sorts. The boulder
counter-example showed that our first definition does not specify a necessary condition for being a chair.
The bench counter-example showed that satisfying the suggested definition is
not sufficient to qualify something
as a chair.
Imaginary counter-examples
When philosophers consider “What is X?” questions, they are
usually interested in providing a definition that succeeds in pinning down the essence of X. Their focus is not on
those features that, merely as a matter
of fact, all and only the Xs happen to possess. Rather, they want to know
what must be true of all and only the
Xs. They want to know what will be true of all and only the Xs, not just in the
actual situation, but in any possible
situation.
But then we
can undermine such a definition by coming up with a merely possible counter-example. Take the boulder-chair example
discussed above. Perhaps no one has ever used a conveniently shaped boulder as
an item of garden furniture. That is irrelevant. As the definition of a chair
is supposed to say what is true of all and only the chairs in any possible situation, so a merely possible counter-example will do.
Students
new to philosophy are often confused about this. Confronted with the boulder
chair counter-example, they may point out that as a matter of fact there are no
boulder chairs. But whether or not any such chair exists is irrelevant to its
power as a counter-example. An imaginary boulder-chair is just as effective as
a real. Just so long as it is possible.
We don’t know, and yet we do…(C-heading)
In the dialogue the Laches,
Socrates asks the eponymous Athenian general “What is courage?” Laches defines
courage as standing firm in battle.
But Socrates quickly comes up with a counter-example – someone might stand firm
in battle, but simply out of foolish endurance, putting both themselves and
others in danger. That would not be courage. A genuinely courageous person
knows both when to stand firm and when to retreat.
After several more abortive
attempts to define courage, Socrates concludes that, though there must be some
essential feature common and peculiar to all acts of courage in virtue of which
they are courageous, we are remain ignorant
about what this essential feature is. It seems that the “essence” of courage is hidden.
Yet the method Socrates employs
in order to try to show this – the method of counter-examples - suggests that,
at some level, we do possess this
knowledge.
After all, Laches is able to recognise that someone who foolishly holds fast in battle is not
truly courageous. He recognises that such a person is a counter-example to his
definition. But then Laches must, at some level, already know what courage is. If Laches didn’t know what courage
was, how would he be able to recognise that he has been confronted with a
counter-example?
So it seems
as if the knowledge we seek is, in a sense, something we already possess. It
is, if you like, buried within us (in fact Socrates believes it is innate). It’s just that we are not able
to bring this knowledge to the surface and make it clear and explicit. The
method of counter-examples is designed to help us do this.
P211
CAPTION. A beautiful […], a beautiful {….}.. and a beautiful
{…}. All these things are beautiful. But what is beauty itself? Plato concludes it is something that exists in addition to
all the particular beautiful things. See page XX.
P212
TEXT BOX. Necessary
and sufficient conditions. In asking the question “What is X?” philosophers
are typically looking for a special sort of definition.
Here is an example of such a definition:
Something is a triangle if and
only if it is a three-straight-sided closed figure.
Being a three-straight-sided closed figure is a necessary condition of being triangle –
necessarily, anything that isn’t straight-sided is not a triangle. Being a three-straight-sided closed figure is also sufficient to qualify something as a
triangle - necessarily, if something is a three-straight-sided closed figure,
then it is a triangle.
When
philosophers ask “What is beauty?”, What is knowledge?”, What is justice?” and
so on, they are typically also looking for a definition that supplies the
necessary and sufficient conditions for being an X.
Counter-examples
to such a definition will show either that the definition does not specify a
necessary condition, or that it does not specify a sufficient condition.END
TEXT BOX.
CAPTION: (hand stretching) In Plato’s dialogues, Socrates
concludes that the essence of justice, beauty, courage and so on is hidden from us. Even a courageous
soldier like Laches unable to define what courage is.
P213
NEW IMAGE OF CHAIR (TO REPLACE BELL QUOTE): CAPTION: We all know what a chair is. Or do we? It
can be remarkably difficult to pin down what’s essential so far as being a chair is concerned. One way in
which we might try to do this is by applying the method of counter-examples.
CAPTION: “But
what is art?” Such “What is
X?” questions often crop up in dinner party conversations. The method of
counter-examples may well be employed.
P214
Family resemblance (B
heading)
CAPTION (photo). Family Resemblance. The members of a family
may all look similar even when there is no one feature they all share.
CAPTION (graphic). These faces strongly resemble each other.
Some have the same XXX, others the same XX, and other share the same XX. Yet,
despite these overlapping similarities, there is no one feature they all
possess.
INTRODUCTION: In the preceding section we looked at the
method of counter-examples. In Plato’s dialogues, Socrates supposes there must
be one thing that, say, all and only the beautiful things possess in virtue of
which they are beautiful. Socrates then demolishes various suggestions as to
what this one feature might be by applying the method of counter-examples. By
why assume there must be such a
common feature? That there must be
such a common denominator is famously questioned by Wittgenstein.
MAIN TEXT. About540 words.
Socrates supposes there must be one thing all beautiful
things have in common in virtue of which they are beautiful, one thing all
examples of courage possess in virtue of which they are courageous, and so on.
Similarly, the philosopher of art Clive Bell, when addressing the question
“What is visual art?” assumes that there must be one quality that all works of
visual art have in common in virtue of which they are works of visual art:
For either all works of visual art
have some common quality, or when we speak of “works of art” we gibber. …There
must be some one quality without which a work of art cannot exist… What is this
quality?
Yet we can struggle to identify what this quality is.
Indeed, the history of Western philosophy is in large part constituted by
unsuccessful attempts to identify these elusive common denominators.
The philosopher Ludwig
Wittgenstein suggests that the hunt for the common quality may, in many cases,
be a wild goose chase.
Take a look at these faces. Some
have the same eyes, others the same nose, and so on. Yet, despite these
overlapping similarities, there is no one
feature shared by all the faces. Wittgenstein calls this kind of similarity
“family resemblance”. And he suggests that many of our concepts may be family
resemblance concepts. Wittgenstein illustrates with the example of games:
Consider for example the
proceedings that we call “games”. I mean board-games, card-games, ball-games,
Olympic games, and so on. What is common to them all? — Don’t say: “There must
be something common, or they would not be called ‘games’— For if you look at
them you will not see something that is common to all, but similarities,
relationships, and a whole series of them at that. To repeat: don’t think, but
look!— Look for example at board-games, with their multifarious relationships.
Now pass to card-games; here you find many correspondences with the first
group, but many common features drop out, and others appear. When we pass next
to ball-games, much that is common is retained, but much is lost…[T]he result
of this examination is: we see a complicated network of similarities
overlapping and criss-crossing:
sometimes overall similarities, sometimes similarities of detail. I can think
of no better expression to characterize these similarities than “family
resemblances”; for the various resemblances between members of a family: build,
features, colour of eyes, gait, temperament, etc. etc. overlap and criss-cross
in the same way. — And I shall say: ‘games’ form a family.
Clive Bell assumes there must be one quality that all works
of visual art have in common. But perhaps visual art is also a family
resemblance concept. Perhaps there is only an overlapping series of
resemblances among works of visual art, as there is in the case of games. If
art is a family resemblance concept, then Clive Bell’s attempt to pin down the
one quality possessed by all examples of visual art is indeed a wild goose
chase.
The moral
is: whenever you are confronted by a “What is X?” question, it is always worth
considering whether X might be a family resemblance concept. Don’t just assume that there must be some one quality all examples of Xs have in common.
P215
QUOTE INSERT THE CLIVE BELL QUOTE ON THIS PAGE (MOVED FROM P
214)
ILLUSTRATED BOX
We can easily introduce a family resemblance concept. Let’s
define “widget” as follows. Something is a widget if and only if it possesses three of the following six characteristics:
1. It is portable
2. It costs over £200
3. It can be blown through
4. It makes a noise
5. It is longer than it is wide
6. It has holes
This kazoo, clarinet and a python are all widgets. This
kite, chair and football are non-widgets. Note that there is no one feature
that all widgets must possess. [END
ILLUSTRATED BOX]
Reasonableness comes in degrees (B heading)
INTRO: Beliefs can be more
or less reasonable. There is, if you like, a scale of reasonableness on which beliefs may be located.
Unfortunately, that reasonableness is a matter of degree is often overlooked.
It’s sometimes assumed that if neither a belief A, nor its denial B, are
conclusively “proved”, then the two beliefs must be more or less equally
reasonable or unreasonable. As we will see, this assumption is false.
MAIN TEXT. Some beliefs are very reasonable indeed. It’s
reasonable for me to believe that the orange on the table in front of me
exists, because I can see it there. It’s also reasonable for me to believe that
the tree outside my house still exists, because it was there when I last
looked, and I have no reason to suppose anyone has removed it in the meantime.
And it is reasonable for me to believe that Japan exists, despite the fact that
I have never actually been there. I possess an enormous amount of evidence that
Japan exists, and hardly any evidence to suggest it doesn’t.
Of course,
despite being highly reasonable, these beliefs could still conceivably turn out
to be false. Perhaps the orange I seem to see before me is an hallucination.
Perhaps the tree in my garden has secretly been removed by pranksters. In the
film The Truman Show, there is a
conspiracy to dupe the main character into thinking he is living his life out
in the real world when in fact everything around him is part of a carefully
managed TV set. Even those he believes to be his closest relatives are, in
truth, merely actors. Perhaps I am the unwitting victim of a similar complex
conspiracy to make me believe Japan exists when in fact it doesn’t.
So let’s
acknowledge I might be mistaken in
holding these beliefs. Certainly, I cannot prove them beyond all doubt. But of
course, this is not to say these beliefs aren’t eminently reasonable. They
clearly are. They lie towards the top of
the scale of reasonableness.
At the
bottom of the scale lies the belief that faeries and goblins exist. This is a
very unreasonable thing to believe because there’s no good evidence these tiny
folk exist and plenty of evidence that they are fictional. Still, it does
remain a remote possibility that these fairy-tale folk exist. We can’t prove
beyond all doubt that they don’t.
Around the
middle of the scale of reasonableness lie beliefs which are neither highly
reasonable nor highly unreasonable. Take the belief that there are intelligent
life forms living somewhere out there in the universe. True, we have no direct
evidence of any such extra-terrestrial intelligence. On the other hand, we know
that intelligent life has evolved on this planet, and we also know that there
are countless other similar planets out there. So it’s not particularly
improbable that there is intelligence out there somewhere.
Beliefs can change their position
on this scale over time. A few decades ago, belief in electrons was fairly reasonable. Given the additional
scientific evidence that’s since been discovered, it is now very reasonable. At
one time belief that the world is flat was not particularly unreasonable. It’s
now very unreasonable indeed.
The scale may also vary from one
person to the next. It’s very reasonable for me to believe there is an orange
on the table in front of me, because I can see it there. Perhaps it’s not quite so reasonable for you to believe
there’s an orange there. After all, you can’t see the orange. You simply have
to take my word for it.
Of course, it’s contentious where
some beliefs lie. Take belief in the existence of God, for example. Some
consider belief God is no more reasonable than belief in fairies. Others
believe it is fairly reasonable – at
least as reasonable as, say, belief in extra-terrestrial intelligence. Those
who claim to have had direct experience of God, or who think miracles and so on
constitute fairly good evidence that God exists, may place belief fairly high
up on the scale (even while acknowledging that their belief is not “proved”).
The “You can’t prove it” move
Having set up the scale of reasonableness, let’s now look at
a common mistake people make when assessing the reasonableness of a belief.
Sometimes, when someone has been
given very good grounds for supposing a belief B belief is false, they respond
by saying “But you can’t prove B is
false, can you? B might be true!”
They think this shows belief B is still pretty reasonable – perhaps even as
reasonable as the belief that B is false.
Here is an example. Suppose you
have just provided Ted with excellent grounds for supposing his belief that
there are fairies at the bottom of the garden is false. Ted responds “But you
can’t prove there are no faeries down
there, can you?”, as if that showed that his belief is, after all, pretty
reasonable – perhaps even as reasonable as yours. Now perhaps you can’t prove beyond all doubt
that there are no faeries. It’s just possible that you’re mistaken. Still,
it’s hardly likely, given the evidence. On the available evidence, Ted’s belief
remains downright silly.
Here’s a philosophical example.
Even if we cannot conclusively prove either that God does exist or that he
doesn’t, it doesn’t follow that the belief that God exists is just as
reasonable or unreasonable as the belief that he doesn’t. It might still be the
case that there are very good grounds for supposing God exists, and little
reason to suppose he doesn’t. In which case it is far more reasonable to
believe in God than it is to deny his existence. Conversely, there might be
powerful evidence God doesn’t exist, and little reason to suppose he does. In
which case atheism may be by far the most reasonable position to adopt. We
should not allow the fact that neither belief can be conclusively proved to
obscure the fact that one belief might not be far more reasonable than the
other.
Unfortunately, theists sometimes
respond to atheist arguments by pointing out the atheist has not conclusively proved there is no God, as if that
showed belief in God must be fairly reasonable after all. Actually, even if the
atheist can’t conclusively prove there is no God, they might still succeed in
showing that belief in God is very unreasonable indeed – perhaps even as
unreasonable as belief in fairies.
Pointing out the absence of
“proof” against a belief does not show that the belief is, after all, at least
fairly reasonable
P218
QUOTATION. REMOVE RUSSELL QUOTE AND REPLACE WITH IMAGE:
IMAGE OF A RECTANGLE, LEFT HALF RED MIDDLE HALF WHITE AND RIGHT HALF GREEN. IN
LEFT-HAND RED HALF PUT “DISPROVED” IN RIGHT HAND GREEN HALF, PUT “PROVED” IN
MIDDLE BOX PUT “NEITHER PROVED NOR DISPROVED”. Caption: Rather than arranging
beliefs on the scale of reasonableness, we might sort them instead into the
three boxes “proved, “disproved” and “neither proved nor disproved”. We may
then lose sight of the fact that the beliefs in the middle box may still differ
dramatically in terms of their reasonableness.
CAPTION. In the film The
Truman Show, the central character, played by Jim Carey, believes he is
living his life out in an ordinary small town, when it is in fact a TV set and
everyone is an actor.
P219
CAPTION . Here is a series of beliefs about what exists
arranged on a scale indicating roughly how reasonable they are (we might argue
over exactly where they should appear
on the scale). Some beliefs are very reasonable indeed (despite not being
beyond all doubt). Others are highly unreasonable (though there remains the
remote possibility they might be
true).
P220
QUOTE – REPLACE DAWKINS QUOTE WITH THIS. “If neither belief
A nor it’s denial, B, can be conclusively proved, both are fairly reasonable.” The you-can’t-prove-it move.
QUOTE – DELETE LUTHER QUOTE AND REPLACE WITH TEXTBOX. The ambiguity of “proved” People often talk about a belief being
“proved”, “not proved”, “disproved”, and so on. But what does “proved” mean
here? It can mean a variety of things, including:
Proved beyond all possible doubt
Proved beyond reasonable doubt
Shown to be certain
Shown to be almost certainly true
Shown to be very probably true
Notice that people often talk of “scientific proof” despite
the fact that most, perhaps all, scientific claims are open to at least some doubt.
When using the term “proved” it
is important to be clear what you mean. Take for example, the claim that we
cannot “prove” God exists. It might be true we can’t “prove” beyond all
possible doubt God exists. But then perhaps we can still “prove” God exists in
the sense we can still show his existence to be extremely probable, or to be at least beyond reasonable doubt. Conversely, even if we can’t “prove” beyond all
doubt God does not exist, it doesn’t follow that we can’t show his existence to
be extremely improbable. We should
not allow loose use of the word “proved” to obscure these facts.
CAPTION DELETE MOTHER
THERESA. REPLACE WITH IMAGE OF GOD. Caption: Where should we place “God exists”
on the scale of reasonableness? Indeed, should belief in God appear on the scale
at all (but if it doesn’t appear on the scale, why not?)
P221
Category mistakes (B heading)
CAPTION: (phrenology head) CHANGE THIS IMAGE TO SOMETHING
RELATED TO “GHOST IN THE MACHINE”. Caption: Ryle believed that the Cartesian
mind – an immaterial entity that exists in
addition to the physical organism and its various behavioural dispositions
– is a mere “ghost in the machine”.
CAPTION (oxford colleges). The tourist who says “Yes, I know
where all the different colleges are, but now where is the University?” has made a category mistake.
INTRO. Someone commits a category mistake when the
mistakenly assume that if A, B, C and D all belong to the same category of
thing, then so must E. For example, the tourist who asks, “Yes, I know where
all the different colleges are, but where is the University?” has made a category mistake. The University is not
another building alongside the other colleges. Rather it is the overarching
institution to which the various colleges belong.
MAIN TEXT Here is another example. Suppose you invite
someone in to see your home. You show them the living room, dining room,
kitchen, bathroom and bedrooms. But at the end of the tour, your guest looks
mystified. “That was all very pleasant” they say, “But can you now show me your
home.” Your guest has made a category
mistake. They have assumed that your
home is a further thing in addition
to the various rooms they have visited. The truth, of course, is that those
rooms together constitute your home.
The
expression “category mistake” was introduced by the philosopher Gilbert Ryle in
his book The Concept of Mind. Ryle
believes Descartes makes a this type of mistake in supposing the mind is a
further entity in addition to physical objects like tables, mountains and our
physical bodies. That leads Descartes to suppose that, as the mind is not a
physical object, it must be an immaterial object – a sort of “ghost in the
machine”. The truth, claims Ryle, is that to possess a mind is to possess a
whole series of behavioural dispositions. As they are dispositions even
physical organism can possess, so no further immaterial “something” is
required. To suppose otherwise is, according to Ryle, to commit a category
mistake.
Comments
Great stuff, Although I haven't got through it all yet.
You list the shoes sticking out from the curtain as:
"an example of inductive reasoning."
Isn't this Abductive reasoning?
And in this part shouldn't the first line be If the power is off?
"If the power is on, the light won’t come on
The light won’t come on
Therefore the power is off"