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The Reliability of Sense Perception

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This monograph deals with a perennial philosophical question: whether sense perception generates reliable information about the external world. The author, William Alston, reviews the contemporary philosophical literature and analyzes arguments purporting to demonstate that sense perception is reliable; he can find no argument, whether a priori or experiential, that doesn't fall into circularity by tacitly assuming that sense perception is reliable. Nevertheless, he concludes that it's rational to rely conditionally on sense perception even if we can't prove that it's reliable: we have no choice but to rely on our senses in practice, and there's no reason to think they're systematically misleading us. Along the way, Alston discusses private languages, brains in vats, and evil demons.

I've never been gripped by the problems of epistemology, nor entirely convinced they aren't pseudo-problems. I didn't like "The Matrix," either. I did, however, like this modest, intelligent book very much. I had to read some paragraphs two or three times in order to grasp their meaning fully, but that was only because the material was difficult (at least for me), not because Alston writes badly. He actually writes quite clearly for an academic philosopher. I knocked off one star only because Alson didn't situate his analysis within the history of philosophy. That was too bad, since much of his argumentation recasts in modern language 18th-century debates between David Hume and Thomas Reid. General readers are entitled to intellectual history along with technical philosophy!

This is the broad question that epistemologist William Alston addresses in this work; the title topic -- the reliability of sense perception -- he holds to be a special case of the reliability of basic doxastic (belief-forming) practices generally.

"Sense perception," as Alston deals with it here, covers a variety of more or less customary ways of forming beliefs, and Alston designates the whole lot of them as "sensory perception practice" (abbreviated SP throughout most of the work). The problem he faces to begin with is that there does not seem to be a _noncircular_ demonstration that SP is reliable in this way. (Though admitting that not all circularity is vicious, he nevertheless decides to avoid circular arguments himself and -- rather too summarily, I think -- dismisses coherence theories "without a hearing" for the purposes of this work.)

He devotes the bulk of the work to considerations of various sorts of argument for the reliability of SP -- simple "track record" and pragmatic arguments, _a priori_ arguments including theological ones, and empirical arguments. The burden of his own argument here is essentially to show (a) that the noncircularity problem affects all direct arguments for the reliability of SP, and (b) that this problem is not unique to SP but affects _all_ of our usual ways of forming beliefs.

His concluding chapter takes an interesting tack. He contends that even though it is not possible to offer a _direct_ (noncircular) argument that SP is reliable, nevertheless practical rationality shows that it _is_ rational to "engage in SP (and other doxastic practices)" -- that is, practical reason demands that we do go ahead and form our beliefs in the ordinary accepted ways. His claim at this point is that, although he has not shown that SP _is_ reliable, he has shown that it is rational to _suppose_ SP to be reliable.

His distinction here is one that he takes to be crucial, so it will be as well to spell it out precisely. His claim, he says, is not that in judging SP to be rational, he is thereby _judging_ that it is rational to suppose that SP is reliable; his claim is that the judgment that SP is rational _is itself a commitment_ to the rationality of judging SP to be reliable.

Got that? Well, for further elaboration you'll have to read the book itself. At any rate, his conclusion is that SP is just one of a whole host of doxastic practices in which it is _practically_ rational to engage; he has not, as he readily admits, shown that it is rational "in an _epistemic_ sense" to judge that SP is reliable.

After a brief discussion of why this sort of rationality is relevant and more or less sufficient, he turns in closing to a short survey of ways in which this rationality might be undermined (by "overriders of prima facie rationality") or supported (by "significant self support"). His final remark is that there is some urgency about deciding how to regard doxastic practices which can be neither avoided nor shown to be reliable.

The argument of this volume is a development of his work in _Perceiving God_, in the third chapter of which he discussed the impossibility of proving SP reliable in a noncircular way. At bottom the present work is an expanded version of that chapter, offered -- as Alston says -- to "philosophers who would not open a book entitled _Perceiving God_" but might find the argument on sense perception interesting in its own right.

Those potential readers might include some from the "Objectivist" camp -- at least those who recognize the woeful inadequacies in Ayn Rand's own sweep-it-under-the-rug policy on the question Alston here addresses. In particular, readers of David Kelley's _The Evidence of the Senses_ might like to read through Alston's very different approach.

A couple questions about Alston's omissions:

1) Why doesn't he include dreams as being reason to doubt SP's reliability?

2) Why doesn't he include rationality and practicality as doxastic practices?


And it might have better benefited Alston to realize that the threat of epistemic circularity works two ways (this regards his final chapter anyway): Where he claims one cannot make a case for reason's reliability without presupposing reason (thus its unsupportable reliability), the same goes for the converse: You can't refute reason without presupposing it, so any reduction would beg the question as well.

So the case for reason's (and like doxastic practices') reliability begs the question, but this question begging is informed by the question begged. This epistemic "problem", if it is one, is a little more polygonal than circular.

This is an otherwise shrewd and clearly written book.

And that's all I got.


PEACE

One of the central questions in philosophy is the reliability of sense perception. That is, how do we know that our senses are (generally speaking) reliable and what method (if any) is there to determine whether they are reliable on any specific occasion?

Although we assume that our senses give us accurate information about a world "out there" providing good arguments for this belief isn't so simple. Take the philosopher Ayn Rand: she never actually explained what method we use to determine whether the senses are, on any given occasion, accurate (although this hasn't prevented her followers from asserting that she - and she alone - has "solved" the problem).

Throughout the history of philosophy, numerous answers have been given. Prof. William Alston discusses these answers in this compact and readable book. (Actually, his discussion is somewhat broader: by the reliability of sense perception, Prof. Alston means a "doxastic practice" of belief formation which goes from sense perception to beliefs about the physical and social environment.) As he notes, many of the arguments in favor of the reliability of sense perception can be broken down into "a priori" and empirical arguments. Some of the a priori arguments provide a satisfactory refutation of skepticism, but don't provide any reason to think that the senses are more generally accurate than not. (Although he doesn't mention Rand's argument that skepticism is self-refuting because "existence exists," similar arguments are discussed.) Many of the empirical arguments appear to provide reasons for believing that the sense perception is reliable (because they provide a good track record in making predictions and the like) yet they assume what needs to be proved: that the senses are in fact reliable.

Prof. Alston closes the book with his own argument in favor of the reliability of sense perception (which I confess I didn't understand very well) and an evaluation of the arguments offered.

This is the first book I've read by Prof. Alston. I think I'll be reading his A REALIST CONCEPTION OF TRUTH next.