I believe Searle's view of consciousness is valid as far as it goes; and it is a refreshing change from more mainstream views. There is, however, a very serious omission in his theory, which is the main weakness of his book: his lack of any discussion of the function served by consciousness.
Searle repeats, in many statements throughout his book (such as the statement quoted above from p. 1), that consciousness is caused by neurophysiological processes. However, he never says that consciousness, in turn, it causes anything.
The closest Searle comes to addressing this issue is in his brief discussion, and rejection, of epiphenomenalism:
The fact that the mental features are supervenient on neuronal features in no way diminishes their causal efficacy. The solidity of the piston is causally supervenient on its molecular structure, but this does not make solidity epiphenomenal; and similarly, the causal supervenience of my present back pain on micro events in my brain does not make the pain epiphenomenal. [20]
However, this is a purely negative discussion, and as such, seems purely terminological. There is no positive discussion of what it is that the back pain --- or some other mental phenomenon --- causes, and whether it causes anything beyond the sum of what its micro-event constituents cause by themselves. And without such a positive discussion, the substance of Searle's view becomes indistinguishable from epiphenomenalism.
Searle explicitly separates consciousness from behaviour. He discusses several thought-experiments, in which a person's brain is replaced by silicon components which cause precisely the same behaviour as his original brain, but without being conscious. [21] Searle's motivation for these thought-experiments is laudable; he is attacking the behaviourist notion that consciousness is reducible to certain types of behaviour. However, he ends up implying much more than a rejection of behaviourism; he implies a total separation of consciousness from behaviour, and, consequently, a view of consciousness as having no physical effects.
I believe the basic problem, at the root of this omission, is in Searle's false separation of ontology from causation.
I need first to make explicit the distinctions between ontology, epistemology, and causation. There is a distinction between answers to the questions, What is it? (ontology), How do we find out about it? (epistemology), and What does it do? (causation). For example, in the case of the heart, the ontology is that it is a large piece of muscle tissue in the chest cavity; the epistemology is that we find out about it by using stethescopes, EKGs, and in a pinch we can open up the chest and have a look; and the causation is that the heart pumps blood through the body. [22]
Searle's distinction, in this passage, between ontology and epistemology, is completely valid and very important. However, his separation of ontology and causation is invalid. The heart's capacity to pump blood through our body is an essential aspect of what the heart is.
This is a basic point in which Searle would benefit greatly from the insights of Objectivism. The Objectivist-Aristotelian view of causality is as the law that entities must act according to their identity.
The law of causality is the law of identity applied to action. All actions are caused by entities. The nature of an action is caused and determined by the nature of the entities that act; a thing cannot act in contradiction to its nature. [23]
On this view, ontology and causation can't be separated. In contrast, on the Humean view of causality --- as connection of events to events --- ontology and causation are only incidentally related, and so Searle's separation makes sense. This separation is the source of Searle's attempt to explain what consciousness is without any account of what it does.
A related, more specific, error on Searle's part is his view of teleology, and of its relation to Darwinian evolution.
There is nothing normative or teleological about Darwinian evolution. Indeed, Darwin's major contribution was precisely to remove purpose and teleology from evolution, and substitute for it purely natural forms of selection. Darwin's account shows that the apparent teleology of biological processes is an illusion. .... There is no factual difference about the heart that corresponds to the difference between saying (1) The heart causes the pumping of blood. and saying, (2) The function of the heart is to pump blood. But 2 assigns a normative status to the sheer brute causal facts about the heart, and it does this because of our interest in the relation of this fact to a whole lot of other facts, such as our interest in survival. In short, Darwinian mechanisms and even biological functions themselves are entirely devoid of purpose or teleology. All of the teleological features are entirely in the mind of the observer. [24]
This is a very common misinterpretation of the meaning of Darwinism. Searle accepts it completely, and it plays a central --- and unfortunate --- role in his approach to the nature of consciousness.
Darwin was himself a strong advocate of natural teleology, and explicitly saw his theory of evolution as a vindication of teleology. His approach to teleology, however, was significantly different from the approaches prevalent at the time, in that it did not involve divine design or an internal vital force; with no explicit philosophical defense of Darwin's view of teleology, his theory was widely misunderstood as rejecting teleology. Several recent writers, however, have provided theories of teleology which fit, and allow a full, explicit understanding of, Darwin's form of teleological explanation. [25]
Biological functions share two essential characteristics with conscious purposes: the organ or faculty has value-significance for the organism; and it exists it because of this value-significance. An organism's needs, the requirements of its survival, have the same role for unconscious biological functions as desires have for conscious, purposeful action; they determine what is beneficial, or of value, to the organism. And structures and faculties are naturally selected for their benefit to the organism's survival. The previous instances of a biological faculty in the organism's ancestors have contributed to their survival, thus making it possible for this organism to be born and, consequently, for this faculty to operate in it. A biological organ or faculty's value-significance for the organism --- as manifested in previous instances of the same organ or faculty --- is therefore the cause of its existence. This is the basis for classifying this value-significance as its "final cause", or goal.
Note that this basis is intrinsic to the facts about the organism and its evolution; it does not depend on the observer. To take Searle's example of the heart, there is a factual difference between 1 and 2; 2 states that the heart causes the pumping of blood, that the pumping of blood helps the organism's survival, and that the heart's existence was caused, through natural selection, by the beneficial effects of its capacity to pump blood. It is therefore an intrinsic fact about the heart that its function is to pump blood (rather than, for example, to produce a thumping sound).
Therefore, on a proper understanding of teleology and its relation to Darwinian evolution, the function that any biological faculty serves in the organism's life is a central aspect of its identity. An understanding of consciousness --- as of the heart-beat, digestion, or any other biological faculty --- depends on a thorough understanding of its effects and of its goal. On Searle's view, on the other hand, the existence of consciousness does not serve any goal, except as an attribution made to it by an observer; and, consequently, its effects, if any, are a minor aspect of its nature.
Searle does devote a brief discussion to the selectional advantage of consciousness. [26] His claim on this point is:
We can make a general claim about the selectional advantage of consciousness: Consciousness gives us much greater powers of discrimination than unconscious mechanisms would have.
This is a valid point. It is quite similar to David Kelley's discussion of the role of consciousness, as a means of discriminating the larger amount of information available to the more complex animals, and of controlling choices among the larger range of actions open to them. [27]There is, however, a significant difference: for Kelley, this is a crucial point regarding the nature of consciousness, central to his discussion; for Searle, it is no more than an afterthought, discussed in a brief section and not integrated to the rest of his theory. Searle clearly regards this as a very minor point about consciousnesse; as his earlier discussion of the silicon-brain thought experiments demonstrates, he sees nothing wrong in principle with the possibility that you could have precisely the same powers of discrimination, and consequently the same behaviour, without consciousness.
The basic reasons for this difference, between Searle and Kelley's approaches to this point, are the two points I discuss above: Kelley accepts the Objectivist-Aristotelian view of causality, as the law of identity applied to action. And he accepts the Objectivist view of natural teleology. The combination of these two implies that the results of consciousness in action, and the goal it serves in the organism's life, are central to understanding its nature.
There is also another reason for this difference between Kelley's and Searle's approaches. While Rand wrote very little about the basic nature of consciousness, she did write a very detailed discussion of one central aspect of the workings of human consciousness --- namely, the conceptual faculty. [28] Her central focus in that entire discussion is the goal which the conceptual faculty serves for man's life: the principle of unit-economy. All her points about the workings of the conceptual faculty are always fully integrated to this idea of the faculty's goal. Her approach in that discussion serves as a model, which other Objectivists, such as Kelley, follow in their discussions of other aspects of consciousness. I believe that this model served an important role in setting Kelley's approach to discussing the basic nature of consciousness. And it is precisely this model which is sorely lacking for Searle.