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Jackson rehearses another argument that is mounted against 'physicalism' (and thus against our example of physicalism, the identity hypothesis: the 'modal argument'.
THIS ARGUMENT TAKES AS ITS PREMISE THE PROPOSITION THAT NO AMOUNT OF PHYSICAL
INFORMATION ABOUT A PERSON LOGICALLY ENTAILS THAT HE OR SHE IS CONSCIOUS
OR 'FEELS' SOMETHING OR IS 'AWARE'.
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statement of physical state
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If this premise is granted, goes the argument, there can be no logical contradiction in postulating that a person with exactly my physical constitution and present state might not be conscious.
Do you agree that a person with exactly my physical constitution and present state might not be conscious?
This can be put in terms of the concept of the possible world.
You can think of the concept of a 'possible world' as a way of thinking about things that 'must' be true, a way that hopes to be illuminating.
We are prepared to say sometimes that such and such a thing MUST be true. We want to say more than that it just IS true.
For example we might say brothers MUST be male.
Or, to take a type of example that could be quite different, we might say the angles of a triangle MUST add up to two right angles, or that 2 added to two MUST equal four.
Another kind of example: we might want to say: when I leave go of this computer it MUST fall (unless something else comes in to prevent it).
It is suggested that these claims can be expressed in terms of possible worlds.
There is no possible world in which there is a brother who is not male.
If a triangle MUST have angles summing to two right angles, there is no possible world in which there are triangles with angles that don't add up like that.
The same with 2+2=4.
When it comes to unsupported things falling, it is not so obvious that this can be expressed by saying that there is no possible world in which unsupported things don't fall.
In fact you may say it's not obvious at all - that in fact there is a sense in which a possible world has computers in it which fly up when 'dropped'.
So 'things must fall if they are heavy and unsupported' has a different kind of necessity from 'the angles of a triangle must sum to two right angles.' And there may be a difference again in the necessity of the claim 'brothers must be male'.
Let's just notice, to locate another bit of jargon, that some claims do not involve any kind of necessity at all. I may say 'I got up late this morning' and mean to imply that this didn't happen by any kind of necessity.
You may of course be a determinist, holding that everything I do is necessary, in the sense that 'unsupported things fall' is necessary. But still you will need something to deny. What you will want to deny is that 'I got up late this morning, but not through any kind of necessity'.
Claims that such and such happened, but not through any kind of necessity are sometimes called 'contingent'.
Finally another term: 'possible'.
Things that happen but don't happen out of necessity - contingencies - are in a clear sense 'possible'. They are possible, for the very good reason that they actually happen. But you may think that there are some things that are possible and yet don't happen.
You could toy with a three-fold division: things that happen out of necessity, things that happen but not out of necessity, and things that don't happen at all, but are possible.
(I am talking here about events here. Perhaps a corresponding categorization could be erected in terms of claims, or propositions.)
The absence of necessity is possibility. If an event happens, but not out of necessity, it is just a 'possible' event.
There is a technical term for the different kinds of 'necessity' and it's absence - 'possibility'? - that we meet up with here and elsewhere. The term is 'modality'. "Brothers are necessarily male" is said to have a different modality from "I got up late this morning', where this is meant to report a contingency.
The notion of a possible world is used to 'model' propositions in modal logic.
This is just to try and establish common ground for the notions of necessity, contingency and possibility.
If there is no logical entailment between physical state and being conscious
we could say there is a possible world in which the same physical state existed
without the person whose state it was being in that world conscious.
It would be a possible world like ours in every respect, except for the fact
that my doppleganger say would not be conscious.
What do you think:is there such a possible world?
This reminds us of Place.
He wanted to deny that there was any logical entailment between physical state
of brain and state of consciousness.
He wanted to insist that the connection was, if anything, a contingent one.
He is someone who would be committed to the view therefore that
it would be conceivable,
it would be within the bounds of logical possibility
that there should be one
without the other:
the same physical state,
without the consciousness
that as a matter of contingent fact
goes along with that state in the world we know.
Put it in the language of possible worlds:
Place would be a person
who would have to acknowledge
that one possible world
would be one where
there was the same physical state
but no consciousness.
So far we have said just this, that according to the modal argument you can
take as a premiss that
a statement recording your physical state
would not entail
- logically entail -
anything about your state of consciousness.
Put in terms of possible worlds, it is the premiss that
there is a possible world which is exactly like ours except that no one and
nothing is aware or conscious in it.
BUT IF THAT HAS TO BE ACCEPTED, WHAT CAN BE SHOWN TO FOLLOW?
SIMPLY THAT THESE TWO WORLDS ARE PROFOUNDLY DIFFERENT, AND THAT SOMETHING IS
CLEARLY MISSING FROM THE OTHER ONE.
WHAT IS MISSING?
WE KNOW IT ISN'T ANYTHING PHYSICAL - THE TWO WORLDS ARE PHYSICALLY IDENTICAL.
IT MUST BE SOMETHING OTHER THAN PHYSICAL.
ERGO, THERE IS SOMETHING MORE THAN PHYSICAL TO HUMAN BEINGS.
Is the modal argument effective against the identity hypothesis? As we have
seen, the identity hypothesis only purports to be a contingent claim. It specifically
admits that there is no logical entailment between statement of physical state
and statement of state of consciousness.
Jackson says the difficulty with the modal argument is that not everyone agrees with its premiss.
'SOME SINCERELY DENY THAT THERE CAN BE PHYSICAL REPLICAS OF US IN OTHER POSSIBLE
WORLDS WHICH NEVERTHELESS LACK CONSCIOUSNESS.' JACKSON, IN LYCAN, P.472.
Is this position coherent?
This is an argument for the inadequacy of physicalism which has been very influential.
I think it's difficult to be sure what the argument is. Here is one possibility:
We can never know what it is like to be a bat, because the sensory apparatus and the way of life of a bat is so different from our own. Physicalism can never account for this impossibility. Therefore it is inadequate.
Nagel attaches great significance to the fact that a creature which or who is aware has a 'point of view'. It is the 'point of view' of the bat which we can never hope to place ourselves at.
Is this a difficulty for physicalism?
The fact that as a conscious being I look out on the world 'from a point of view' is a feature of conscious experience, I suppose. As an exercise we might try and imagine what experience would be like if it didn't understand itself as experienced 'from a point of view'. (Would washes of emotion get us anywhere near this?)
So the identity theorist would need to say: the conscious experience which includes the sense of having 'a point of view' is identical with a brain process.
But why shouldn't the identity theorist say this?
Some people have reasons for saying No. Jackson put forward the knowledge argument as an objection to Identity Theory. But does the bat argument add to this? Does it represent a new contribution to the debate? Please say what it is if you think it does.
Jackson thinks not.
Having established the reality of qualia, as he sees it, Jackson is anxious
to defend his flank.
He says that one of the main reasons why people try and reject the reality
of qualia is that admitting them commits you to holding that consciousness has
a causal role in determining behaviour.
Jackson considers considers the proposition that qualia are causally impotent,
the idea that though they occur they play no role in influencing the course
of physical events.
He wants to maintain the possibility of there being some properties of mental states which make no difference in the physical world.
He rehearses three reasons for thinking that epiphenomenalism is impossible.
It is just obvious that eg the hurtfulness of a pain is partly responsible for
a person crying out, taking steps to put a stop to it, etc.'
Jackson's reply is that whenever you have a hypothesis that A causes B you can
explain the same facts equally well by positing that A and B are both caused
by C.
We wouldn't have evolved the having of qualia if they did not enhance our survival
value.
Jackson: there are lots of examples of where one thing evolves not because it
has survival value in itself but because it goes along with something that has
survival value. The woolly coat of the polar bear is cited in evidence. This
is both warm (helpful) and heavy (not so).
We only know of other minds because we believe in qualia. We infer from their a person's behaviour to their being conscious (in various ways) - have mental states with qualia.
This inference must be invalid if qualia are not causally efficacious - i.e.
result in the behaviour we are inferring from.
Jackson: The inference could be along the following lines:
'The epiphenomenalist can argue from the behaviour of others back to its causes
in the brains of others and out again to their qualia.' Jackson, in Lycan, 2nd
edition, p.445.
VP
END
