A redated post (with a spelling correction in the title).
Do we perceive physical objects directly, or are the immediate objects of our experience our own sense-data, which may be caused by some state of the physical world? Given that we can certainly have non-veridical experiences, what are we aware of in those cases? What is the direct object of our awareness?
Lewis wrote: “It is clear that everything we know, beyond our immediate sensations, is inferred from those sensations.” He goes on to say
“I do not mean to say that we begin, as children, by regarding our sensations as “evidence” and then arguing consciously to the existence of space, time, matter, and other people. I mean that, if we are old enough to understand the question, our confidence in the existence of anything else is challenged, our argument in defence of it will have to take the form of inferences from our immediate sensations. Put in its most general form the inference would run “Since I am presented with colours, sounds, shapes pleasures, and pains which I cannot perfectly predict and control, and since the more I investigate them the more regular their behaviour appears, therefore there must exist something other than myself and it must be systematic.”
In my study of this passage, and contrary to John Beversluis, I have supposed that this passage is compatible with what is called the direct realist position on perception. We could perceive physical objects directly, nevertheless perhaps when we are challenged about those perceptions we perform inferences in defense of the veridicality of those perceptions.
Nonetheless, we might ask whether direct realism is correct. Edward Feser, in his book Philosophy of Mind: A Short Introduction (Oneworld, 2005), suggests that there is a powerful argument for the indirect realist view of perception:
1. By stimulating the brain so as artificially to produce a neural process that is normally associated with a certain veridical experience, it is possible in principle to bring about a hallucination that is subjectively indistinguishable from that experience.
2. But if the immediate causes of veridical perceptual experiences and their hallucinatory counterparts are of the same sort, then these effects must be of the same sort as well.
3. In the case of hallucinations, the effect is obviously direct awareness not of any external physical object, but rather of a subjective mental, perceptual, representation of an external object.
4. So in the case of veridical perceptual experiences too, what one is directly aware of must be a subjective perceptual representation.
So, do we perceive physical objects directly? And, if we don’t, does this have any effect on the debate between materialists and their opponents?