The final outcome of his intellectual progress is given to us in
The Problems of Life and Mind, which may be regarded as the crowning work of his life. His sudden death cut short the work, yet it is complete enough to allow a judgment on the author's matured conceptions on biological, psychological and metaphysical problems.
The first two volumes on
The Foundations of a Creed lay down what Lewes regarded as the true principles of philosophizing—he tried to effect a
rapprochement between metaphysics and science. He is still positivist enough to pronounce all inquiry into the ultimate nature of things fruitless. What matter, form, and spirit are in themselves is a futile question that belongs to the sterile region of "metempirics." But philosophical questions may be so stated as to be susceptible to a precise solution by
scientific method. Thus, since the relation of subject to object falls within our experience, it is a proper matter for philosophic investigation. It may be questioned whether Lewes is right in thus identifying the methods of science and philosophy. Philosophy is not a mere extension of scientific knowledge; it is an investigation of the nature and validity of
epistemology itself. In any case Lewes cannot be said to have done much to aid in the settlement of properly philosophical questions.
His whole treatment of the question of the relation of subject to object is vitiated by a confusion between the scientific truth that mind and body coexist in the living organism and the philosophic truth that all knowledge of objects implies a knowing subject. In other words, to use
Shadworth Hodgson's phrase, he mixes up the question of the genesis of mental forms with the question of their nature (see
Philosophy of Reflexion, ii. 40-58). Thus he reaches the
monistic doctrine that mind and matter are two aspects of the same existence by attending simply to the parallelism between psychical and physical processes given as a fact (or a probable fact) of our experience, and by leaving out of account their relation as subject and object in the cognitive act.
His identification of the two as phases of one existence is open to criticism, not only from the point of view of philosophy, but from that of science. In his treatment of such ideas as "sensibility," "sentience" and the like, he does not always show whether he is speaking of physical or of psychical phenomena. Among the other properly philosophic questions discussed in these two volumes the nature of the casual relation is perhaps the one which is handled with most freshness and suggestiveness.
The third volume,
The Physical Basis of Mind, further develops the writer's views on
organic activities as a whole. He insists strongly on the radical distinction between organic and inorganic processes, and on the impossibility of ever explaining the former by purely mechanical principles. With respect to the nervous system, he holds that all its parts have one and the same elementary property, namely, sensibility. Thus sensibility belongs as much to the lower centres of the spinal cord as to the brain, contributing in this more elementary form elements to the
subconscious region of mental life. The higher functions of the nervous system, which make up our conscious mental life, are merely more complex modifications of this fundamental property of nerve substance.
Closely related to this doctrine is the view that the nervous organism acts as a whole, that particular mental operations cannot be referred to definitely circumscribed regions of the brain, and that the
hypothesis of nervous activity passing in the centre by an isolated pathway from one
nerve cell to another is altogether illusory. By insisting on the complete coincidence between the regions of nerve action and sentience, and by holding that these are but different aspects of one thing, he is able to attack the doctrine of animal and human
automatism, which affirms that feeling or consciousness is merely an incidental concomitant of nerve action and in no way essential to the chain of physical events. Lewes's views in
psychology, partly opened up in the earlier volumes of the
Problems, are more fully worked out in the last two volumes (3rd series). He discusses the method of psychology with much insight.
He claims against Comte and his followers a place for introspection in psychological research. In addition to this subjective method there must be an objective, which consists partly in a reference to nervous conditions and partly in the employment of sociological and historical data. Biological knowledge, or a consideration of the organic conditions, would only help us to explain mental functions, as feeling and thinking; it would not assist us to understand differences of mental faculty as manifested in different races and stages of human development. The organic conditions of these differences will probably for ever escape detection. Hence they can be explained only as the products of the social environment.
This idea of dealing with mental phenomena in their relation to social and historical conditions is probably Lewes's most important contribution to psychology. Among other points which he emphasizes is the complexity of mental phenomena. Every mental state is regarded as compounded of three factors in different proportions—namely, a process of sensible affection, of logical grouping and of motor impulse. But Lewes's work in psychology consists less in any definite discoveries than in the inculcation of a sound and just method. His biological training prepared him to view mind as a complex unity, in which the various functions interact one on the other, and of which the highest processes are identical with and evolved out of the lower. Thus the operations of thought, "or the logic of signs," are merely a more complicated form of the elementary operations of sensation and instinct or "the logic of feeling."
The whole of the last volume of the
Problems may be said to be an illustration of this position. It is a valuable repository of psychological facts, many of them drawn from the more obscure regions of mental life and from abnormal experience, and is throughout suggestive and stimulating. To suggest and to stimulate the mind, rather than to supply it with any complete system of knowledge, may be said to be Lewes's service in philosophy. The exceptional rapidity and versatility of his intelligence seems to account at once for the freshness in his way of envisaging the subject matter of philosophy and psychology, and for the want of satisfactory elaboration and of systematic co-ordination.
