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(Greek nous ; Latin mens , German Geist , Seele ; French ame esprit ).

The word mind has been used in a variety of meanings in English, and we find a similar want of fixity in the connotation of the corresponding terms in other languages. Aristotle tells us that Anaxagoras, as compared with other early Greek philosophers, appeared like one sober among drunken men in that he introduced nous , mind, as efficient cause of the general order in the universe. In treating of the soul, Aristotle himself identifies nous with the intellectual faculty, which he conceives as partly active, partly passive (see INTELLECT). It is the thinking principle the highest and most spiritual energy of the soul, separable from the body, and immortal. The Latin word, mens , was employed in much the same sense. - St. Thomas, who represents the general scholastic usage, derives mens from metior (to measure). He identifies mens with the human soul viewed as intellectual and abstracting from lower organic faculties. Angels, or pure spirits, may thus be called minds (De Veritate, X, a. 1). For Descartes the human soul is simply mens, res cogitans , mind. It stands in complete opposition to the body and to matter in general. The vegetative faculties allotted to the soul by Aristotle and the Schoolmen are rejected by him, and those vital functions are explained by him mechanically. The lower animals do not possess minds in any sense; they are for him mere machines. An early usage in English connects the word mind closely with memory, as in the sentence "to bear in mind". Again it has been associated with the volitional side of our nature, as in the phrases "to mind" and "to have a mind to effect something". Still when restricted to a particular faculty the general tendency has been to identify mind with the cognitive and more especially with the intellectual powers. In this usage it more closely corresponds to the primary meaning of the Latin mens , understood as the thinking or judging principle. Mind is also conceived as a substantial being, equivalent to the scholastic mens , partly identified with, partly distinguished from the soul. If we define the soul as the principle within me, by which I feel, think, will, and by which my body is animated, we may provide a definition of mind of fairly wide acceptance by merely omitting the last clause. That is, in this usage mind designates the soul as the source of conscious life, feeling, thought, and volition, abstraction being made from the vegetative functions. On the other hand the term soul emphasizes the note of substantiality and the property of animating principle.

In the English psychological literature of the last century there has indeed been exhibited a most remarkable timidity in regard to the use of the term " soul ". Whilst in German at all events the word seele has been in general acceptance among psychologists, the great majority of English writers on mental life completely shun the use of the corresponding English word, as seemingly perilous to their philosophical reputation. Even the most orthodox representatives of the Scotch school rigorously boycotted the word, so that "the nature and attributes of the Human Mind", came to be recognized as the proper designation of the subject matter of psychology, even amongst those who believed in the reality of an immaterial principle, as the source of man's conscious life. However, the spread of the positivist or phenomenalist view of the science of psychology has resulted in a very widely adopted identification of mind merely with the conscious states, ignoring any principle or subject to which these states belong. The mind in this sense is only the sum of the conscious processes or activities of the individual with their special modes of operating. This, however, is a quite inadequate conception of the mind. It may, of course, be convenient and quite legitimate for some purposes to investigate certain activities or operations of this mind or soul, without raising the ultimate question of the metaphysical nature of the principle or substance which is the basis and source of these phenomena; and it may also serve as a useful economy of language to employ the term mind, merely to designate mental life as a stream of consciousness. But the adoption of this phraseology must not cause us to lose sight of the fact that along with the action there is the agent, that underlying the forms of mental behaviour there is the being which behaves. The connection of our abiding personal identity, nay the simplest exercise of self-conscious memory, compels us to acknowledge the reality of a permanent principle, the subject and connecting bond of the transitory states. Mind adequately conceived must thus be held to include the subject or agent along with states or activities, and it should be the business of a complete science of mind to investigate both.

All our rational knowledge of the nature of the mind must be derived from the study of its operations. Consequently metaphysical or rational psychology logically follows empirical or phenomenal psychology. The careful observation, description, and analysis of the activities of the mind lead up to our philosophical conclusions as to the inner nature of the subject and the source of those activities. The chief propositions in regard to the human mind viewed as a substantial principle which Catholic philosophers claim to establish by the light of reason are, its abiding unity, its individuality, its freedom, its simplicity, and its spirituality (see CONSCIOUSNESS; INDIVIDUALITY; INTELLECT; SOUL).


In connection with the investigation of our mental operations there arises the question, whether these are to be deemed coextensive with consciousness. Are there unconscious mental processes? The problem under different forms has occupied the attention of philosophers from Leibniz to J. S. Mill, whilst in recent years the phenomena of hypnotism, "multiple personality ", and abnormal forms of mental life have brought the question of the relation between the unconscious and the conscious processes in the human organism into greater prominence. That all forms of mental life, perception thought, feeling, and volition are profoundly affected in character by nervous processes and by vital activities, which do not emerge into the strata of conscious life, seems to be indisputably established. Whether however, unconscious processes which affect conclusions of the intellect and resolutions of the will, but are in themselves quite unconscious, should be called mental states, or conceived as acts of the mind, has been keenly disputed. In favour of the doctrine of unconscious mental processes have been urged the fact that many of our ordinary sensations arise out of an aggregate of impressions individually too faint to be separately perceivable, the fact that attention may reveal to us experiences previously unnoticed, the fact that unobserved trains of thought may result in sudden reminiscences, and that in abnormal mental conditions hypnotized, somnambulistic, and hysterical patients often accomplish difficult intellectual feats whilst remaining utterly unaware of the rational intermediate steps leading up to the final results. On the other side it is urged that most of those phenomena can be accounted for by merely subconscious processes which escape attention and are forgotten; or, at all events, by unconscious cerebration, the working out of purely physical nervous processes without any concomitant mental state till the final cerebral situation is reached, when the corresponding mental act is evoked. The dispute is probably, at least in part, grounded on differences of definition. If, however, the mind be identified with the soul, and if the latter be allowed to be the principle of vegetative life, there can be no valid reason for denying that the principle of our mental life may be also the subject of unconscious activities. But if we confine the term mind to the soul, viewed as conscious, or as the subject of intellectual operations, then by definition we exclude unconscious states from the sphere of mind. Still whatever terminology we may find it convenient to adopt, the fact remains, that our most purely intelectual operations are profoundly influenced by changes which take place below the surface of consciousness.


A related question is that of the simple or composite character of consciousness. Is mind, or conscious life, an amalgam or product of units which are not conscious ? One response is offered in the "mind-stuff" or "mind-dust" theory. This is a necessary deduction from the extreme materialistic evolutionist hypothesis when it seeks to explain the origin of human minds in this universe. According to W. K. Clifford, who invented the term "mind-stuff", those who accept evolution must, for the sake of consistency, assume that there is attached to every particle of matter in the universe a bit of rudimentary feeling or intelligence, and "when the material molecules are so combined as to form the film on the under-side of a jelly fish, the elements of mind-stuff which go along with them are so combined as to form the faint beginnings of sentience. When the matter takes the complex form of the living human brain, the corresponding mind-stuff takes the form of human consciousness, having intelligence and volition" (Lectures and Essays, 284). Spencer and other thorough-going evolutionists are driven to a similar conclusion. But the true inference is rather, that the incredibility of the conclusion proves the untenableness of the materialistic form of evolution which these writers adopt. There is no evidence whatever of this universal mind-stuff which they postulate. It is of an inconceivable character. As Professor James says, to call it "nascent" consciousness is merely a verbal quibble which explains nothing. No multiplicity and no grouping or fusing of unconscious elements can be conceived as constituting an act of conscious intelligence. The unity and simplicity which characterize the simplest acts of the mind are incompatible with such a theory.


The opposition of mind and matter brings us face to face with the great controversy of Dualism and Monism. Are there two forms of being in the universe ultimately and radically distinct? or are they merely diverse phases or aspects of one common underlying substratum? Our experience at all events appears to reveal to us two fundamentally contrasted forms of reality. On the one side, there is facing us matter occupying space, subject to motion, possessed of inertia and resistance permanent indestructible, and seemingly independent of our observation. On the other, there is our own mind, immediately revealing itself to us in simple unextended acts of consciousness, which seem to be born and then annihilated. Through these conscious acts we apprehend the material world. All our knowledge of it is dependent on them, and in the last resort limited by them. By analogy we ascribe to other human organisms minds like our own. A craving to find unity in the seeming multiplicity of experience has led many thinkers to accept a monistic explanation, in which the apparent duality of mind and matter is reduced to a single underlying principle or substratum. Materialism considers matter itself, body material substance, as this principle. For the materialist, mind, feelings, thoughts, and volitions are but "functions" or "aspects" of matter; mental life is an epiphenomenon , a by-product in the working of the Universe, which can in no way interfere with the course of physical changes or modify the movement of any particle of matter in the world; indeed, in strict consistency it should be held that successive mental acts do not influence or condition each other, but that thoughts and volitions are mere incidental appendages of certain nerve processes in the brain; and these latter are determined exclusively and completely by antecedent material processes. In other words, the materialistic theory, when consistently thought out, leads invariably to the startling conclusion that the human mind has had no real influence on the history of the human race.

On the other hand, the idealistic monist denies altogether the existence of any extra-mental, independent material world. So far from mind being a mere aspect or epiphenomenon attached to matter, the material universe is a creation of the mind and entirely dependent on it. Its esse is percipi. It exists only in and for the mind. Our ideas are the only things of which we can be truly certain. And, indeed, if we were compelled to embrace monism, it seems to us there can be little doubt as to the logical superiority of the idealistic position. But there is no philosophical compulsion to adopt either a materialistic or an idealistic monism. The conviction of the common sense of mankind, and the assumption of physical science that there are two orders of being in the universe, mind and matter, distinct from each other yet interacting and influencing each other, and the assurance that the human mind can obtain a limited yet true knowledge of the material world which really exists outside and independently of it occupying a space of three dimensions, this view, which is the common teaching of the Scholastic philosophy and Catholic thinkers, can be abundantly justified (see DUALISM; ENERGY, CONSERVATION OF).


Mind is also contrasted with mechanical theories as cause or explanation of the order of the world. The affirmation of mind in this connection is equivalent to teleologism, or idealism in the sense of there being intelligence and purpose governing the working of the universe. This is the meaning of the word in Bacon's well-known statement: "I had rather believe all the fables in the Legend and the Alcoran than that this universal frame is without a mind" (Essays: Of Atheism). It is, in fact, the doctrine of theism. The world as given demands a rational account of its present character. The proximate explanations of much, especially in the inorganic and non-living portion of it, can be furnished by material energies acting according to known laws. But reason demands an account of all the contents of the universe-living and conscious beings as well as lifeless matter- and, moreover, it insists on carrying the inquiry back until it reaches an ultimate explanation. For this, Mind, an Intelligent Cause, is necessary. Even if the present universe could be traced back to a collection of material atoms, the particular collocation of these atoms from which the present cosmos resulted, would have to be accounted for- because in the mechanical or materialistic theory of evolution, that original collocation contained this universe and no other, and that particular collocation clamours for a sufficient reason just as inevitably as does the present complex result. If we are told that the explanation of a page of a newspaper is to be found in the contact of the paper with a plate of set types, we are still compelled to ask haw the prticular arrangement of the types came about, and we are certain that the sufficient explanation ultimately rests in the action of mind or intelligent being.

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