Lecture | Perception and Mind (In)Dependence

notes cribbed from Craig French, 10/13/14

argument structured from critique by Paul Snowden, How to Interpret Direct Perception

What is Common-Sense Realism?

What about this challenge from AJ Ayer called the Argument from Illusion?

definitions

Veridical, Veridicality is a semantic or grammatical assertion of the truth of an utterance.

The argument from illusion is an argument for the existence of sense-data. The argument appears to show the need to posit sense-data as the immediate objects of perception.

Common-sense realism, Direct realism, Naïve realism The realist view is that we perceive objects as they really are.

Common-Sense Realism

  1. The familiar material objects we ordinarily take the world to be populated by – e.g., tables, stones, pieces of fruit, trees, etc. actually exist.
  2. These familiar objects exist in the manner we ordinarily think they do, i.e. they have a mind-independent existence.
  3. We are sometimes perceptually aware of such mind-independent material objects.

Summary: the world includes material objects, which are mind-independent, and which we sometimes perceive.

Clarify Common Sense Realism

Claim (1) Material Objects

The first claim of Common-Sense Realism is an ontological claim: there are such things as the familiar material objects. So things like apples, chairs, bicycles, and the like, do in fact exist. These are substantial three-dimensional space occupying things; entities which fill space and which can persist through time.

The claim is modest. Not a claim about all there is. (There are also features, events, etc). Not a claim about what is fundamental. (Perhaps material objects are non-basic, build up out of more basic things).

3.2 Claim (2) Mind-Independence

Common-Sense Realism says that material objects are mind-independent in that they don't depend for their existence and nature on our perceptual awareness of them.

Some of them may depend on psychological states.

Metaphysical Awareness-Dependence

For X to be metaphysically awareness-dependent is for it to be of such a kind. For X to exist and be as it is, it must be perceived.

Think of such things as constituted by perceptual awareness: what it is for them to exist is for them to be objects of perceptual awareness. Let's say that metaphysically awareness-dependent entities are mental entities of some kind.

Esse est percipi

Consider Berkeley's dictum: esse est percipi to be is to be perceived. Contrast this with causal awareness-dependence, and counterfactual awareness-dependence, neither of which are sufficient for metaphysical awareness-dependence.

Causal Dependence

The existence of Thing X is caused by of causally sustained by perceptual awareness of Thing X. This is not sufficient for metaphysical awareness-dependence.

Destructive Mechanisms

Suppose that there are destructive mechanisms in place in this building set to detonate explosives which will destroy the building. Now suppose that the mechanisms are being inhibited by our awareness of the building. Our awareness is causally hooked up to the mechanisms in a way which triggers an inhibitor, so the explosives don't detonate. So the building is causally sustained by our awareness of it, thanks to the causal link from our awareness to the inhibitors.

The fate of the building is causally linked to our awareness, even though the building is not a mental entity. The causal dependence of the building on our awareness has nothing to do with the nature of the building. But metaphysical awareness-dependence demands that the thing is an object of awareness because of the very nature it has.

Counterfactual Dependence

If we were not aware of x, x would not exist. (That is, in close possible worlds in which we are not aware of x, x doesn't exist).

We can use the example we just used to show why this can't be su cient for metaphysical awareness- dependence.

... here is another example:

Fruit Ninja Destroyers

Take a piece of fruit where if we were not to be aware of it, it wouldn't exist. For suppose there is a team of Fruit Ninjas who have this policy: they destroy all and only fruit we are not aware of. So if we were not to be aware of the fruit the team of Fruit Ninjas would destroy it, and it wouldn't exist. Thus the fruit is counterfactually dependent upon our awareness of it.

But again, the way the fruit depends on awareness is not traceable to the very nature of the fruit. Just because the Fruit Ninjas will destroy fruit that we are not aware of doesn't mean that it is in the nature of such fruit to be objects of awareness.

So: if x is causally or counterfactually dependent upon awareness, that isn't enough for x to be metaphysically dependent on awareness. (Though if x is metaphysically awareness-dependent, then it is counterfactually awareness-dependent).

The second claim of Common-Sense Realism is then this:

Material objects are not metaphysically awareness-dependent; it is not in their nature that they are perceived, they are not constituted by perceptual awareness of them.

This is very intuitive. We think that things like apples exist in themselves, independently of our awareness of them. We can become aware of them, but becoming aware of them is not their coming to be.

Contrast awareness-independence with Berkeleian Idealism where material objects are mental entities, constituted by perceptions of them. Berkeley holds first that material objects are in fact nothing but bundles of sensible qualities. This apple is a bundle of qualities, a particular color, form and size, and so on. But second, these qualities are nothing but ideas in the mind.

Thus Berkeley thinks of objects as collections of ideas:

And as several of these [ideas] are observed to accompany each other, they come to be marked by one name, and so to be reputed as one thing. Thus, for example, a certain colour, taste, smell, figure and consistence having been observed to go together, are accounted one distinct thing, signified by the name apple. Other collections of ideas constitute a stone, a tree, a book, and the like sensible things...

Berkeley, 1734, 1.1

For Berkeley ideas are metaphysically awareness-dependent entities. It is in their nature that they are objects of perception. This is how we can interpret this remark among others:

it seems no less evident that the various sensations or ideas imprinted on the sense, how- ever blended or combined together (that is, whatever objects they compose) cannot exist otherwise than in a mind perceiving them (1.3).

If we put all of this together, the apple itself – and objects more generally – are metaphysically awareness- dependent; nothing but bundles of mental entities of a certain kind, namely, ideas. Thus Berkeley is able to say

The table I write on, I say, exists, that is, I see and feel it... [For such objects] their esse is percipi, nor is it possible they should have any existence, out of the minds or thinking things which perceive them (1.3).

Objection!

surely things like apples will continue to exist even if we direct our attention away from them. Or even if we all perished and there was no perception left at all! Reply: Berkeley distinguished between finite spirits or minds – like ours – and the infinite spirit or mind: God.

The qualities and ideas which comprise the apple are awareness-dependent but they depend upon the all encompassing mind of God who perceives at all times. We may go out of the room and not perceive the apple, but it still remains insofar as it is constituted by the mind of God.

In claiming that material objects are awareness-independent

the Common-Sense Realist endorses Realism about material objects

as opposed to Idealism. Here realism is a label for the position that material objects are metaphysically awareness-independent.

3.3 Claim (3) – Perceptual Awareness

Consciously seeing an object is one way of being perceptually aware of it, so is feeling an object, hearing an object, and so on. Common-sense is committed to the idea that we are sometimes perceptually aware of mind-independent material objects.

Following David Hume (1748/1772)

... suppose the very images, presented by the senses, to be the external objects, and never entertain any suspicion, that the one are nothing but representations of the other. This very table, which we see white, and which we feel hard, is believed to exist, independent of our perception, and to be something external to our mind, which perceives it. Our presence bestows not being on it: our absence does not annihilate it. It preserves its existence uniform and entire, independent of the situation of intelligent beings, who perceive or contemplate it .

Common-Sense Realism makes an even more modest claim:

we are sometimes perceptually aware of mind-independent material objects

We might also be aware sometimes of awareness-dependent entities.

We recognize two categories of perceptual awareness:

  1. Veridical experience: e.g., where one sees an apple and has an experience in which it looks red to one, and it in fact is that way.
  2. Illusory experience: e.g., where one sees an apple and has an experience in which it looks red to one, when in fact it is some other color, e.g., green.

Compare these experiences to hallucinations

Dig the phosphorescent rat playing guitar!

We don't think that hallucinations are cases of perceptual awareness. They are cases where it seems to one as if one has perceptual awareness, but one doesn't. This is because in such cases the things one seems to be aware of are not there (or if they are, there being there is irrelevant to the experience which is a result of, e.g., some brain malfunction, or, e.g., a drug, or whatever, not the object).

An experience counts as perceptual awareness of an object only if (a) the object is there (to be seen, heard, felt, etc), and (b) the object is relevant in some sense to the experience one has.

Note that it is a matter of debate what it takes for an object to be relevant to the experience one has: must it cause it? If so, in what way? Perhaps instead it is part of what constitutes it?

We won't get into these debates...

Our ordinary stance on veridical and illusory experiences is that they are forms of perceptual awareness, satisfying these conditions. Hallucination is not a form of perceptual awareness because it fails to satisfy either condition.

The Common-Sense Realist idea that we are sometimes perceptually aware of mind-independent material objects is correct for illusory and veridical experiences of material objects.

This common-sense idea is important for at least two reasons

  1. it articulates something that seems to be true about our relationship to reality. It forms part of our how we understand ourselves as beings in the world.
  2. it is part of what informs (1) and (2) of Common-Sense Realism. We so readily admit that there are mind-independent material objects because when we reflect upon our relationship to reality we see ourselves as beings who sometimes perceive such objects.

This is why reflecting upon perception can guide us, as it does, to a conception of the world as a world involving these familiar objects, existing independently of our awareness of them.

Strawson, 1979.

Challenges to claim (3, Perceptual Awareness) of Common-Sense Realism are thus important: if the claim is false, then

  1. we have to re-think our conception of how we relate to reality.
  2. though it doesn't show that there aren't any mind-independent material objects, it will mean that we face a serious question about why we believe there are.

Ayer's Argument from Illusion

The Argument from Illusion tries to show that we are never perceptually aware of mind-independent material objects. The argument has a two-stage structure.

  1. In illusions we are not perceptually aware of material objects. The stage Snowdon calls the Base Case Stage and the claim it aims to establish is what French calls the Interim Negative Claim.
  2. This is the Spreading Step, aims to generalize the Interim Negative Claim to veridical cases too, and so we end up with what we can call The Negative Claim: we are never perceptually aware of material objects.

The Base Case Stage

  1. When one is subject to an illusory experience, there sensibly appears to a subject to be something which has a sensible quality, F, which the mind-independent material object supposedly being perceived does not actually have.
  2. (Phenomenal Principle) When, in perceptual experience, it sensibly appears to one that something has a sensible quality, F, then there is something of which one is aware which does have this quality.

Therefore,

  1. (Interim Negative Claim) In cases of illusion, one is no taware of the mind-independent material object one takes oneself to be aware of. (Since the mind-independent object doesn't have the quality F.)

The Spreading Step

(iv) The same account of experience must apply to both illusory experiences and veridical experiences.

Therefore,

(v) (Negative Claim) One is never aware of mind-independent material objects in perceptual experience.

Example.

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Take Bob who looks at a pure white wall in peculiar lighting conditions so as it looks yellow to him.

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The Base Case

  1. It seems that the wall has the quality of yellowness, yet the wall is not yellow.
  2. Bob is perceptually aware of something which is yellow.
  3. Since the wall is not yellow, Bob is not aware of the wall after all.

right

The Spreading Step

  1. The same account of experience must apply to both illusory experiences and veridical experiences.

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Therefore,

  1. Even in a supposed veridical experience of a yellow wall, Bob is not aware of the wall.

Watch Teller's illusion and discuss in terms of Common-Sense Realism and the Argument from Illusion.

References

  • Berkeley, George (1734). A Treatise Concerning the Principles of Human Knowledge.
  • Hume, David (1748/1772). An Enquiry Concerning Human Understanding.
  • Snowdon, Paul F. (1992). "How to Interpret 'Direct Perception'". In: The Contents of Experience. Ed. by
  • Tim Crane. Cambridge: Cambridge University Press, pp. 48–78.
  • Strawson, P. F. (1979). "Perception and its Objects". In: Perception and Identity: Essays Presented to
  • A. J. Ayer with His Replies. Ed. by Graham Macdonald. London: Macmillan.
  • Craig French (cf397) — 13/10/14