Mechanistic and Nonmechanistic ScienceThe following is the beginning of a discussion in Chapter One of Mechanistic and Nonmechanistic Science on the inability of modern science to explain consciousness.
The life sciences are now dominated by the idea that life can be completely understood within the framework of chemistry and physics. Those who subscribe to this viewpoint say that we can explain all features of life--from the metabolic functioning of cells up to the mental phenomena of thinking, feeling, and willing--as the consequences of underlying chemical processes. This viewpoint has become so pervasive that it is generally presented in biology courses as the only valid understanding of life. Thus, in textbook after textbook we read that "life means chemical and physical organization,"(1) and that "all of the phenomena of life are governed by, and can be explained in terms of, chemical and physical principles."(2)
Yet despite the popularity of this view, we can point to at least one feature of life--the phenomenon of conscious awareness--that is not amenable to a molecular explanation. The basic phenomenon of conscious awareness is the most immediate aspect of our experience, and it is automatically presupposed in all our sensations, feelings, and thought processes. Yet even though consciousness certainly exists and is of central importance to our lives, the current theoretical framework of biological and physical science cannot even refer to consciousness, much less explain it.
To see this, let us examine the process of conscious perception through the eyes of modern science. Our examination will take us through several levels of successively increasing detail, and at each level we will try to ascertain whether our scientific picture of reality sheds any light on the nature of consciousness.
First let us consider a man observing a physical object--in this case, a thermometer. The figure below depicts the operation of the man's sense of sight on the grossest biological level. The process of perception begins when light reflected from the thermometer is focused on the retina of the man's eye, forming an inverted image. This light induces chemical changes in certain retinal cells, and these cells consequently stimulate adjacent nerve cells to transmit electrical impulses. These cells in turn stimulate activity in other nerve cells, and a systematic pattern of pulses is transmitted down the optic nerve. The image of the thermometer is now encoded in this pattern of pulses.
When these pulses reach the brain, a very complicated response occurs, involving many electrochemical actions and reactions. Although scientists at present do not know the details of this brain activity, they are nonetheless in substantial agreement about the basic phenomena involved. When the impulses streaming down the optic nerve reach the brain, they modify the overall pattern of chemical concentrations and electrical potentials maintained by the brain's vast network of nerve cells. This pattern is believed to represent in coded form the specific content of the man's thoughts and sensory impressions. As time passes, the physiochemical transformations of this pattern give rise to sequences of electrical impulses that emerge from the brain along various motor nerves, and these impulses in turn evoke corresponding sequences of muscular contractions. These organized contractions constitute the man's gross external behavior, which may include spoken reports of his sensations, such as "I am seeing a thermometer."
At this point in our investigation, we can understand how descriptions of this kind may, at least in principle, shed light on a person's external behavioral responses to environmental stimuli. We can easily imagine constructing a machine involving photocells and electronic circuitry that would respond to a red light by playing a tape recording of the statement "I am seeing a red light." On a more sophisticated level, we can visualize a computer that will analyze the images produced by a television camera and generate spoken statements identifying various objects. Thus although we are grossly ignorant of the actual physical transformations occurring in the brain, we can at least conceive of the possibility that these may correspond to processes of symbol manipulation analogous to those that take place in computers. We can therefore imagine that the man's statement, "I am seeing a thermometer," is generated by a computational process physically embodied in the electrochemical activity of the nerve cells in the brain.
But all this tells us nothing about the man's conscious perceptions. Our description of the image formed on the retina of the man's eye says nothing about the conscious perception of that image, nor do scientists suppose that conscious perception takes place at this point. Likewise, the statements that light-sensitive cells in the retina have been stimulated and that sequences of nerve impulses have been induced convey nothing at all about the actual subjective experience of seeing the thermometer.
Many scientists feel that conscious perception must take place in the brain. Yet our description of the brain, even if elaborated in the greatest possible detail, would consist of nothing more than a list of statements about the electrochemical states of brain cells. Such statements might have some bearing on patterns of behavior, but they cannot explain consciousness, because they do not even refer to it.
Last updated on January 2, 1996.
© 2004 Govardhan Hill Publishing