for a real bug. Since the subjective experiences can be indistinguishable from that which we have when (as we commonly say) we really see a bug, it is reasonable to infer (the representative realist argues) that in normal perception, when we take ourselves to be seeing a real bug, we are also directly aware of a buglike image in the mind. A hallucination differs from a normal perception, not in what we are aware of (in both cases it is a sense-datum) but in the cause of these experiences. In normal perception it is an actual bug; in hallucination it is, say, drugs in the bloodstream. In both cases, though, we are caused to have the same thing: an awareness of a buglike sense-datum, an object that, in normal perception, we naively take to be a real bug (thus saying, and encouraging our children to say, that we see a bug). The argument from illusion points to the fact that our experience of an object changes even when the object that we perceive (or say we perceive) remains unchanged. Though the physical object (the bug or whatever) remains the same color, size, and shape, what we experience (according to this argument) changes color, shape, and size as we change the lighting, our viewing angle, and distance. Hence, it is concluded, what we experience cannot really be the physical object itself. Since it varies with changes in both object and viewing conditions, what we experience must be a causal result, an effect, of both the object we commonly say we see (the bug) and the conditions in which we view it. This internal effect, it is concluded, is a sense-datum. Representative realists have also appealed to the fact that perceiving a physical object is a causal process that takes time. This temporal lag is most dramatic in the case of distant objects (e.g., stars), but it exists for every physical object (it takes time for a neural signal to be transmitted from receptor surfaces to the brain). Consequently, at the moment (a short time after light leaves the object’s surface) we see a physical object, the object could no longer exist. It could have ceased to exist during the time light was being transmitted to the eye or during the time it takes the eye to communicate with the brain. Yet, even if the object ceases to exist before we become aware of anything (before a visual experience occurs), we are, or so it seems, aware of something when the causal process reaches its climax in the brain. This something of which we are aware, since it cannot be the physical object (it no longer exists), must be a sense-datum. The representationalist concludes in this ‘time-lag argument,’ therefore, that even when the physical object does not cease to exist (this, of course, is the normal situation), we are directly aware, not of it, but of its (slightly later-occurring) representation.
Representative realists differ among themselves about the question of how much (if at all) the sense-data of which we are aware resemble the external objects (of which we are not aware). Some take the external cause to have some of the properties (the so-called primary properties) of the datum (e.g., extension) and not others (the so-called secondary properties – e.g., color).
Direct (or naive) realism shares with representative realism a commitment to a world of independently existing objects. Both theories are forms of perceptual realism. It differs, however, in its view of how we are related to these objects in ordinary perception. Direct realists deny that we are aware of mental intermediaries (sensedata) when, as we ordinarily say, we see a tree or hear the telephone ring. Though direct realists differ in their degree of naïveté about how (and in what respect) perception is supposed to be direct, they need not be so naive (as sometimes depicted) as to deny the scientific facts about the causal processes underlying perception. Direct realists can easily admit, e.g., that physical objects cause us to have experiences of a particular kind, and that these experiences are private, subjective, or mental. They can even admit that it is this causal relationship (between object and experience) that constitutes our seeing and hearing physical objects. They need not, in other words, deny a causal theory of perception. What they must deny, if they are to remain direct realists, however, is an analysis of the subjective experience (that objects cause us to have) into an awareness of some object. For to understand this experience as an awareness of some object is, given the wholly subjective (mental) character of the experience itself, to interpose a mental entity (what the experience is an awareness of) between the perceiver and the physical object that causes him to have this experience, the physical object that is supposed to be directly perceived.
Direct realists, therefore, avoid analyzing a perceptual experience into an act (sensing, being aware of, being acquainted with) and an object (the sensum, sense-datum, sensation, mental representation). The experience we are caused to have when we perceive a physical object or event is, instead, to be understood in some other way. The adverbial theory is one such possibility. As the name suggests, this theory takes its cue from the way nouns and adjectives can sometimes be converted into adverbs without loss of descriptive content. So, for instance, it comes to pretty much the same thing whether we describe a conversation as animated (adjective) or say that we conversed animatedly (an adverb). So, also, according to an adverbialist, when, as we commonly say, we see a red ball, the red ball causes in us (a moment later) an experience, yes, but not (as the representative realist says) an awareness (mental act) of a sense-datum (mental object) that is red and circular (adjectives). The experience is better understood as one in which there is no object at all, as sensing redly and circularly (adverbs). The adverbial theorist insists that one can experience circularly and redly without there being, in the mind or anywhere else, red circles (this, in fact, is what the adverbialist thinks occurs in dreams and hallucinations of red circles). To experience redly is not to have a red experience; nor is it to experience redness (in the mind). It is, says the adverbialist, a way or a manner of perceiving ordinary objects (especially red ones seen in normal light). Just as dancing gracefully is not a thing we dance, so perceiving redly is not a thing – and certainly not a red thing in the mind – that we experience. The adverbial theory is only one option the direct realist has of acknowledging the causal basis of perception while, at the same time, maintaining the directness of our perceptual relation with independently existing objects. What is important is not that the experience be construed adverbially, but that it not be interpreted, as representative realists interpret it, as awareness of some internal object. For a direct realist, the appearances, though they are subjective (mind-dependent) are not objects that interpose themselves between the conscious mind and the external world. As classically understood, both naive and representative realism are theories about object perception. They differ about whether it is the external object or an internal object (an idea in the mind) that we (most directly) apprehend in ordinary sense perception. But they need not (although they usually do) differ in their analysis of our knowledge of the world around us, in their account of fact perception. A direct realist about object perception may, e.g., be an indirect realist about the facts that we know about these objects. To see, not only a red ball in front of one, but that there is a red ball in front of one, it may be necessary, even on a direct theory of (object) perception, to infer (or in some way derive) this fact from facts that are known more directly about one’s experiences of the ball. Since, e.g., a direct theorist may be a causal theorist, may think that seeing a red ball is (in part) constituted by the having of certain sorts of experience, she may insist that knowledge of the cause of these experiences must be derived from knowledge of the experience itself. If one is an adverbialist, e.g., one might insist that knowledge of physical objects is derived from knowledge of how (redly? bluely? circularly? squarely?) one experiences these objects.
By the same token, a representative realist could adopt a direct theory of fact perception. Though the objects we directly see are mental, the facts we come to know by experiencing these subjective entities are facts about ordinary physical objects. We do not infer (at least at no conscious level) that there is a bug in our soup from facts (known more directly) about our own conscious experiences (from facts about the sensations the bug causes in us). Rather, our sensations cause us, directly, to have beliefs about our soup. There is no intermediate belief; hence, there is no intermediate knowledge; hence, no intermediate fact perception. Fact perception is, in this sense, direct. Or so a representative realist can maintain even though committed to the indirect perception of the objects (bug and soup) involved in this fact. This merely illustrates, once again, the necessity of distinguishing object perception from fact perception.
See also DIRECT REALISM , EPISTEMOLOGY , METAPHYSICAL REALISM , PHILOSOPHY OF MIND , SKEPTICISM , THEORY OF APPEARIN. F.D.