Bridgeman (1992) advocates "a new psychology of plans," however, the time is not yet ripe for a frontal attack on the problem of consciousness, the necessary tools and insights are not yet available and the problem is not yet tractable. Bridgeman mentions several regions of the brain where he proposes that plans are synthesized, modified and executed, but how might one recognize in those areas the plan-executing events that constitute consciousness, and distinguish them from other unconscious forms of information processing? With what alternative possibilities should the hypothesized mechanism be confronted, in order to design critical experiments? If no answers are forthcoming this new definition leaves consciousness as a problem that is, at present, just as intractable as before. And so psychologists and neurophysiologists will, I think, continue for some time yet to chip away at the edges of the consciousness problem.
1.2 Medawar (1967, p. 7) has expressed this "not-yet" aspect of scientific endeavors most felicitously: "No scientist is admired for failing in the attempt to solve problems that lie beyond his competence. The most he can hope for is the kindly contempt earned by the Utopian politician. If politics is the art of the possible, research is surely the art of the soluble. Both are immensely practical-minded affairs. Good scientists study the most important problems they think they can solve."
1.3 A consensus that consciousness, in its full complexity, is not yet a soluble problem does not, however, mean that scientists treat it with benign neglect. Instead, many of us continue to chip away at the the edges: studying sleep and learning and "cognitive" components in the EEG; stimulus filtering, sensory mapping, spatial memory, selective attention and a whole host of other smaller and seemingly tractable problems that are related to various aspects of our conscious experience. Many of these issues go far beyond the "stimulus-response link," which Bridgeman characterizes as "the dominant metatheory in psychology."
1.4 The opinion that the time is not yet ripe for a frontal assault is, nevertheless, always subject to reconsideration in the light of recent developments; and in essence, that is what Bridgeman's target article proposes. A novel definition of consciousness is offered (the operation of the central plan-executing mechanism); and the thesis is advanced that with this definition in hand, broad-scale investigation of the phenomenon can rapidly move forward.
1.5 Providing a new definition for a familiar word is a hazardous undertaking, the more so when a multifaceted concept like consciousness is involved. Despite widespread acceptance of previous definitions (e.g. "self-awareness"), "consciousness" doubtless refers to a different concept -- at least a slightly different one -- for each of us; and such differences are certain to evoke resistance to a new definition. For my own "what-I-mean-by-consciousness", Bridgeman's proposal (consciousness is no more and no less than "the operation of the plan-executing mechanism") puts unsatisfactory constraints on a much broader concept. As I pause between penning one sentence and the next, and let my mind wander, I can selectively pay attention to the ticking of a clock or to the bleating of sheep in the nearby field, to the books I see on the desk or to the fluttering leaves on the tree outside the window. This ability to direct attention in an aimless way, as a sort of "playing" with sensory experience, is for me one of the many reflections of consciousness that seem totally independent of a "plan-executing mechanism." I readily accept that the execution of a plan may involve "conscious" choices among alternative courses of action (noting that Bridgeman also grants the possibility that plans may be unconsciously executed); nevertheless, a definition that makes planning a NECESSARY prelude for "consciousness" (Section 2.10) does violence to "what-I-mean-by-consciousness."
1.6 It would be petty quibbling, however, to raise semantic objections, if the proposed definition were to transform the phenomenon itself -- or a major part of it -- into a soluble problem, as Bridgeman suggests. But what is the experimental program that follows from this definition of consciousness? What should be measured, and where and how, in order to characterize the conscious plan-executing mechanism more fully? Bridgeman (4.3 and 4.4) mentions several regions of the brain where he proposes that plans are synthesized, modified and executed, but how might one recognize in those areas the plan-executing events that constitute consciousness, and distinguish them from other unconscious forms of information processing? With what alternative possibilities should the hypothesized mechanism be confronted, in order to design critical experiments? How can this definition help to answer the classical question of whether a baby or a monkey, a rabbit, a fish or a honeybee can be "conscious"? On these points, Bridgeman is disconcertingly silent; but perhaps his target article will evoke definitive responses to such questions from other commentators.
1.7 If not, it appears to me that this new definition leaves consciousness as a problem that is, at present, just as intractable as before: clearly an interesting and seemingly important topic, but one for which adequate tools and insights for a frontal assault are not yet available. And so psychologists and neurophysiologists will, I think, continue for some time yet to chip away at the edges of the consciousness problem. My own suspicion is that while we wait until the time is ripe, and as our understanding of brain physiology progresses, on a topic-by-topic basis, there will be less and less room for consciousness as a unitary phenomenon or a useful concept. It may eventually vanish like a mirage, representing nothing more than the reification of our present state of ignorance about how brains work. But the suggestion that we may eventually be able to describe human experience fully without reference to consciousness is also a proposition in the "not yet" category, with no concisely definable experimental consequences or predictions yet available.
Bridgman, B. (1992). On the evolution of consciousness and language. PSYCOLOQUY 3(15) consciousness.1
Medawar, P. B. (1967). The Art of the Soluble. Methuen: London