Understanding Epistemology

Duncan Pritchard

Understanding Epistemology: Part 6

Duncan Pritchard

A great deal of our knowledge of the world is gained via our perceptual faculties of sight, hearing, touch, and so forth. For example, my knowledge that I am presently at my desk writing these words is itself largely perceptually gained through, for example, my sight of the computer before me, and my touch of the computer keyboard on my fingers as I type. If we know much of what we think we know, then we must have a great deal of perceptual knowledge. As we will see, however, it is far from obvious that we do have widespread perceptual knowledge of the world around us, at least as that knowledge is usually understood.

     The problem is that the way things look isn't always the way things are – appearances can be deceptive. There are familiar examples of this sort of deception, such as the way a straight stick will look bent when placed underwater, or the mirages that result from wandering dehydrated through a barren desert. In these cases if one were not suitably refining one's responses to one's sensory experiences then one would be led into forming false beliefs. If one did not know about light refraction, for example, then one would think that the stick really is bending as it enters the water. The existence of perceptual error of this sort reminds us that while we must depend upon our perceptual faculties for much of our knowledge of the world, the possibility always remains that these faculties can lead us into forming false beliefs if they are left unchecked.

     In itself, the mere possibility of perceptual error is not terribly worrying. We can, after all, usually correct for misleading perceptual impressions when they occur, such as when we make use of our knowledge of light refraction to account for why straight sticks only appear bent when they enter the water. The problem, then, is not the fallibility of perception. Instead, it is its apparent indirectness. After all, the visual impression caused by a genuine sighting of an oasis on the horizon and the visual impression of an illusory sighting of an oasis on the horizon could be exactly the same. This suggests an “indirect” model of perceptual knowledge, such that what we are immediately aware of when we gain such knowledge is a sensory impression – a seeming – on the basis of which we then make an inference regarding how the world is. That is, in both the deceived and non-deceived “oasis” case just considered, what is common is a sensory impression of an oasis on the horizon which leads one to infer something about the world – that there really is an oasis on the horizon. The difference between the two cases is that while the inference generates a true belief in the non-deceived case, it generates a false belief in the deceived case. In the former case, one is thus in a position to have perceptual knowledge that there is an oasis before one; while in the latter case knowledge is out of the question because one's visual impressions are not a reliable guide to how the world is.

     Reflecting on the indirectness of perceptual experience thus gives rise to a conception of perceptual knowledge known as Indirect Realism . This view, a version of which was defended by John Locke (1632-1704), holds that we gain knowledge of an objective world indirectly by making inferences from our sense impressions. The general idea is that the phenomenon of perceptual illusion highlights the fact that what is presented to us in perceptual experience is not the world itself but merely an impression of the world from which we must draw inferences about how the world really is.

     The main problem with Indirect Realism is that by making our perceptual knowledge inferential it threatens to dislocate us from the world altogether. Intuitively, what I am aware of when I open my eyes is the world itself, not a sensory impression of the world from which I infer specific beliefs about the world. Indeed, once one has departed down the road of Indirect Realism then it is not difficult to see the attraction of a widespread scepticism about our knowledge of an external world. After all, if what I am immediately aware of when I perceive is only an impression of the world, one which could well be (for all I know) misleading, then why should I think that I have any knowledge of how the world really is (as opposed to how it appears)?

     One rather dramatic response to this problem is to deny that there is such a thing as a mind-independent world; that is, deny any conception of the world such that it could be radically different from how it appears to be. This view is known as Idealism , and perhaps the most famous exponent of a version of this position is Bishop Berkeley
(1685-1753). Idealists respond to the problem of how we can have knowledge of the world by claming that perceptual knowledge is not knowledge of a world that is independent of our perception of it, but rather knowledge of a world that is constituted by our perception of it. On this view the world is, so to speak, “constructed” out of appearances rather than being that which gives rise to such appearances, and thus it is not “external” in the relevant sense at all. This is a very dramatic conclusion to draw, and appears to call much of our ordinary conception of the world and our relation to it into question.

     The same applies to more modest versions of Idealism, such as the Transcendental Idealism proposed by Immanuel Kant (1724-1804). While conceding that what we are immediately aware of in sensory experience is not the world itself, Kant nevertheless argued that we are required to suppose that there is an external world that gives rise to this sensory experience since without this supposition we would not be able to make any sense of such experience. Very roughly, the idea is that we can only make sense of our perceptual experiences in terms of their being in response to an external world, even if we are not directly acquainted with this world in perceptual experience. The problem with this sort of approach is that it only demonstrates, at best, that an assumption of realism is necessary if we are to make sense of our perceptual experience, not that this assumption is true . This difficulty is especially pressing given that on the Kantian view one is never directly acquainted with the world itself in perception.

     All this talk of Idealism can make one wonder whether something didn't simply go wrong in our reasoning right at the start of our thinking about this subject matter. How could it be that reflecting on the nature of our perceptual experience of the world has led us to think that perhaps there is no external world to have knowledge of in the first place? With this in mind, it is worth considering the prospects for the simple-minded Direct Realism which allows that we can have direct perceptual knowledge of an external world. A version of this view has been defended by, for example, Aristotle (384-322 BC).

     In its simplest form Direct Realism takes our perceptual experiences at face-value and argues that, at least in non-deceived cases, what we are aware of in perpetual experience is the external world itself. That is, if I am genuinely looking at an oasis on the horizon right now then I am directly aware of the oasis itself, and thus I can have perceptual knowledge that there is an oasis before me without needing to make an inference from the way the world seems to how it is. The motivation behind Direct Realism, besides the obvious attraction that it most accords with common sense, is that other theories of perceptual knowledge, such as Indirect Realism and Idealism, are far too quick to infer from the fact that our perceptual experience could be undetectably misleading, that we are only indirectly aware of the world. The idea is that although it is true that in deceived cases, such as the scenario in which I am visually presented with a mirage of an oasis, I am not directly aware of the world but only with the way the world appears, this should not be thought to entail that in non-deceived cases, such as those in which I am actually looking at an oasis in the distance, I am not directly acquainted with objects in the world. On this view, the fact that I am not always able to distinguish between deceived and non-deceived cases is neither here nor there, since it is not held to be a precondition of perceptual knowledge that one can tell the genuine cases of perceptual knowledge apart from the merely apparent cases.

     Of course, the Direct Realist cannot leave matters at that, since she needs to go on to explain how such a view is to function. For one thing, she needs to develop a theory of knowledge which can allow us to have perceptual knowledge directly via perceptual experience even in cases where one is unable to distinguish deceptive from non-deceptive perception. Nevertheless, given the unattractiveness of Indirect Realism and the versions of Idealism that are suggested by the move to Indirect Realism, Direct Realism is an option that clearly needs to be taken very seriously indeed.

Suggested reading
A Guide Through the Theory of Knowledge , Adam Morton (Blackwell).
Problems of Knowledge: A Critical Introduction to Epistemology , Michael Williams (Oxford University Press).
The Theory of Knowledge: Classical and Contemporary Readings, edited by Louis Pojman (Wadsworth).

Duncan Pritchard is a Reader in Philosophy at the University of Stirling. He is the author of Epistemic Luck (Oxford University Press), and (with M. Blaauw) Epistemology A-Z (Edinburgh University Press).