Nigel Thomas

Galton and subsequent investigators find wide divergences in people's subjective reports of mental imagery. Such individual differences might be taken to explain the peculiarly irreconcilable disputes over the nature and cognitive significance of imagery which have periodically broken out among psychologists and philosophers. However, to so explain these disputes is itself to take a substantive and questionable position on the cognitive role of imagery. This article distinguishes three separable issues over which people can be "for" or "against" mental images. Conflation of these issues can lead to theoretical differences being mistaken for experiential differences, even by theorists themselves. This is applied to the case of John B. Watson, who inaugurated a half-century of neglect of image psychology. Watson originally claimed to have vivid imagery; by 1913 he was denying the existence of images. This strange reversal, which made his behaviorism possible, is explicable as a "creative misconstrual" of Dunlap's "motor" theory of imagination.

Twentieth century philosophy and psychology have been peculiarly averse to mental images. Throughout nearly two and a half millennia of philosophical wrangling, from Aristotle to Hume to Bergson, images (perceptual and quasi-perceptual experiences), sometimes under the alias of "ideas", were almost universally considered to be both the prime contents of consciousness, and the vehicles of cognition. The founding fathers of experimental psychology saw no reason to dissent from this view, it was commonsensical, and true to the lived experience of conscious thinking. However, early in this century, just about when the behaviorist revolution in psychology was loudly declaring the scientific illegitimacy of any attempt to study consciousness, and the concomitant non-existence of imagery (Watson, 1913; see Thomas, 1989), philosophy was undergoing its "linguistic turn", a turn to seeing philosophy as essentially about language rather than the world, even the 'inner' world. For decades, the very concept of the mental image was suspect, and it was certainly banished from playing any major role in theories of mind and of thinking. Ralph Ellis' Questioning Consciousness, together with the recent speculations of certain influential neuroscientists (Edelman, 1992; Damasio, 1994), may be signaling the end this unusual era.

Philosopher's zombies are hypothetical beings behaviorally, functionally, and perhaps even physically indistinguishable from normal humans, but who lack our consciousness. Many people seem to be convinced that such zombies are a real conceptual possibility, and that this bare possibility entails that understanding human consciousness must remain forever beyond the reach of science. However, the conceptual entailments of zombiehood have not been sufficiently examined. This brief article shows that any way of understanding the behavior of zombies that does in fact support the suggested entailment, leads to contradictions and absurdities. Zombies are _not_ conceptually possible

Commentary on "On Specification and the Senses," by Thomas A. Stoffregen and Benoît G. Bardy: Behavioral and Brain Sciences, 24, 195-261 (2001).
The target article's value lies not in its defence of specification, or the "global array" concept, but in its challenge to the paradigm of 5+ senses, and its examples of multiple receptor types cooperatively participating in specific information pick-up tasks. Rather than analysing our perceptual endowment into 5+ senses, it is more revealing to type perceptual systems according to task.

The concepts of imagination and consciousness have, very arguably, been inextricably intertwined at least since Aristotle initiated the systematic study of human cognition (Thomas, 1998). To imagine something is ipso facto to be conscious of it (even if the wellsprings of imaginative creativity are in the unconscious), and many have held that our conscious thinking consists largely or entirely in a succession of mental images, the products of imagination (see, e.g., Damasio, 1994 -- or, come to that, see Aristotle, or Hume, or almost any pre-twentieth century cognitive theorist). A venerable tradition also regards perceptual experiences, the main focus of most recent work on consciousness, as products of the imagination, whose primary function is to integrate sensory inputs and render them meaningful (Thomas, 1998, 1999). As Coleridge (1817) famously put it, primary imagination is "the living power and prime agent of all human perception." A better understanding of imagination is likely to deepen our insight into the nature of consciousness (and, probably, vice-versa)