The Argument from Hallucination

A hallucination is an experience which seems exactly like a veridical perception of an ordinary object but where there is no such object there to be perceived. Like illusions, hallucinations in this sense do not necessarily involve deception. And nor need they be like the real hallucinations suffered by the mentally ill, drug-users or alcoholics. They are rather supposed to be merely possible events: experiences which are indistinguishable for the subject from a genuine perception of an object. For example, suppose one is now having a veridical perception of a snow covered churchyard. The assumption that hallucinations are possible means that one could have an experience which is subjectively indistinguishable—that is, indistinguishable by the subject, “from the inside”—from a veridical perception of a snow covered churchyard, but where there is in fact no churchyard there to be perceived. (For more on hallucination, see the essays collected in Macpherson and Platchias (2013)).
A radical form of the argument again challenges Awareness:

An hallucinatory experience as of an ordinary object as F is not a case of awareness of an ordinary object.
Veridical experiences of ordinary objects as F and their hallucinatory counterparts are to be given the same account.
Therefore, one is not perceptually aware of ordinary objects in veridical experience.

What this argument shows, if it is successful, is that one is not perceptually aware of ordinary objects in veridical experiences. The conclusion here is not as general as the conclusion of the argument from illusion, but the more general conclusion is surely not far off: for it would be difficult to maintain that though one is not perceptually aware of ordinary objects in veridical experiences, there are other cases of experience where one is perceptually aware of ordinary objects. So this argument supports if not entails the rejection of our ordinary conception of perceptual experience. Its aim is to show that an aspect of our ordinary conception of perception is deeply problematic, if not incoherent: perceptual experience cannot be what we intuitively think it is. (It is essentially this problem which Valberg (1992) calls “the puzzle of experience”.) But as with the argument from illusion, the argument can be developed, in supplemented form, to defend the conclusion that we only ever perceptually aware of “non-ordinary” objects (see §3.1).
Once again we can view the argument as having a base case (A) and a spreading step (B) (Snowdon 2005). Unlike with the argument from illusion, the base case here is less controversial: it doesn’t rely on the Phenomenal Principle. We thus don’t need a more complicated argument to support it. (A) simply falls out of what hallucinations are supposed to be, and two principles: first, that awareness of an object is a relation to an object, and second, that relations entail the existence of their relata. For given our principles, if an hallucination as of an ordinary object is to be a mode of awareness of an ordinary object then there must be an ordinary object there for one to perceive. But no such objects are there in hallucinations, therefore, hallucinations are not cases of awareness of ordinary objects.
Where the argument from hallucination is controversial is in the spreading step. The spreading step here gets construed in terms of the idea that veridical experiences and hallucinations are essentially the same; mental events of the same fundamental kind (Martin (2006)). (This doesn’t mean that we lose a distinction between veridical experiences and hallucinations. It just means that the difference between veridical experience and hallucination is not to be found in their intrinsic natures). This claim seems plausible, as from a subject’s perspective an hallucination cannot be told apart from a veridical experience. Thus some will accept (B) and thus deny that we are ever perceptually aware of ordinary objects (see sense-datum theories §3.1), and others will accept (B) but argue that we can still have perceptual awareness of ordinary objects (see intentionalist theories §3.3). But as we’ll see, others will want to secure perceptual awareness of ordinary objects by rejecting (B) and holding that hallucinations and veridical experiences are fundamentally different (see naive realist theories and disjunctivism §3.4).
Though it is not plausible to deny the possibility of illusory experiences (though we may argue about how best to construe them; Anthony (2011) and Kalderon (2011)), the claim that subjectively indistinguishable hallucinations are possible is a little more controversial. How do we really know that experiences like this are possible? (Austin (1962), for instance, expresses scepticism). One way to answer this—though certainly not the only way—is to appeal to a broad and uncontroversial empirical fact about experience: that it is the upshot or outcome of a causal process linking the organs of perception with the environment, that our experiences are the effects of things going on inside and outside our bodies. If this is so, then we can understand why hallucinations are a possibility. For any causal chain reaching from a cause C1 to effect E, there are intermediate causes C2, C3 etc., such that E could have been brought about even if C1 had not been there but one of the later causes (see the entry on the metaphysics of causation). If this is true of causal processes in general, and perceptual experience is the product of a causal process, then we can see how it is possible that I could have an experience of the churchyard which was brought about by causes “downstream” of the actual cause (the churchyard). (This plays into the causal argument discussed in §3.4).

The Argument from Hallucination

The Argument from Hallucination :: تعاليق

The Argument from Hallucination