it does not discuss the question of the ultimate nature of spiritual activity, or the substance of mind, and the related question of the immortality of the soul. These it hands over to the branch of philosophy or metaphysic known as Rational or Inferential Psychology,1 reserving for itself the more modest title of Scientific or Empirical Psychology.

Again, modern psychology has, as a positive science, separated itself from philosophy in another way. As already hinted, the central problem of modern philosophy is the nature and certainty of knowledge. The investigation of this problem was for a time, especially in England by Locke and his successors, carried out by an examination of the contents of mind (ideas and impressions). But it has now come to be recognised that a study of mental processes, e.g., the way in which perceptions and ideas arise, is distinct from a critical inquiry into their validity. As a science, then, psychology confines itself to studying what we call thinking or reasoning as it actually takes place, that is, as a psychical process, determined by certain conditions. The problem of testing the objective validity or truth of our thoughts it hands over to Philosophy or Theory of Knowledge.2

§ 5. Points of Contact between Psychology and Physical Science. In thus separating itself as a positive science from philosophy, psychology has placed itself more on the level of the physical sciences. Its conceptions of mental phenomena, and of laws to be ascertained by induction from these, have in fact been modelled on the pattern of conceptions reached by physical science. More particularly in its consistent determination to deal with all mental processes as subject to the great law of causation, modern psychology has tended to assimilate itself in one important respect to the physical sciences. Not only so, a distinct approximation of psychology to physical science has recently been effected by the growing recognition of the interaction of mind and body. Our knowledge of the way in which mental activity is connected with the bodily life has been greatly advanced by the recent development of the

1 See Hamilton, Lectures on Metaphysics, i. p. 121, etc.; and Wundt, Physiol. Psychologie, p. 8, etc.

* The relation of psychology to philosophy is discussed by Prof. Croom Robertson in Mind, vol. viii. p. I.

PSYCHOLOGY AND PHYSICAL SCIENCE.

5

biological sciences, and more particularly neurology, or the science of the normal functions and functional disturbances of the nervous system. As we shall see presently, a great deal of new and valuable information has been acquired quite recently respecting the nervous conditions of mental activity, and we are now able to conclude with a high degree of probability that every psychical process or psychosis has its correlative nervous process or neurosis; and psychologists, while insisting on the disparity of mental and physical processes, have shown themselves ready to acknowledge and profit from all that physiologists discover with respect to the nervous accompaniments of mental states, and the way in which variations in the former affect the latter.

§ 6. How Psychology separates itself from Physical Science. While the development of the modern science of psychology has thus involved an approximation of this branch of inquiry to physical science, it has not by any means tended to the absorption of the former into the latter.

The modern scientific psychologist follows the tradition of philosophical spiritualism so far as to insist on the radical disparity of the psychical and the physical. He contends that mental phenomena differ, in the nature of their elements and in the mode of their grouping, from physical. A sensation is something intrinsically dissimilar to any form of physical movement, such as presumably takes place in the nervous system. Consequently psychical processes cannot be included in and studied as a part of the functional activities of the bodily organism. However closely connected with these last, they form a group of phenomena of a quite special kind, and needing separate study.

Again, the modern psychologist contends not only that psychical phenomena are different in kind from physical, but that they have to be approached by a different mode of observation from that which is employed in physical investigation. We cannot study thoughts, sentiments, or desires by means of the senses as we study bodily movements. They have to be inspected by what is called internal observation or introspection, a process to be more fully explained in the next chapter. This self-observation has, as we shall see, its own peculiar difficulties, and as the history of the science fully illustrates, the successful

handling of it presupposes particular gifts and a special training in the investigator.1

§ 6a. Special interest of Psychology. Lastly, the modern psychologist contends that his science appeals to a peculiar interest. Every branch of scientific study, as botany, astronomy, geology, derives a special interest from certain peculiarities of its phenomena, e.g., the beauties of plant form and colour, the sublimity of astronomical space and geological time. But the sources of interest which psychology makes use of differ still more widely from those employed by the physical sciences than these last differ one from another. It is our interest in man as contrasted with nature, in human character, life and experience as contrasted with the march of events in the physical world. Psychology, even as positive science, still links itself with that group of studies long since marked off as the moral sciences. A scientific study of the thoughts, passions, impulses of the mind is clearly connected with the solution of the old and everinteresting problems whether man can reach assured knowledge, what is his place and destiny in the universe, what constitutes his duty, and so forth; and while it thus joins on to high speculation, it no less firmly attaches itself to every-day interests, the feeling for all things human, to which modern art and especially fiction appeals, and the practical concern of influencing the thoughts, feelings, and actions of others, as in the work of education and the business of politics.

The term psychology was, according to Sir W. Hamilton, first used by Rudolphus Goclenius of Marburg (1594). The province of empirical psychology was roughly indicated by Bacon when he distinguished a science of the faculties of the soul from the science of the soul itself or substance. It was, however, first definitely marked out by Wolff, whose two principal works (pub. 1755) were Psychologia Empirica and Psychologia Rationalis. In England the idea of a scientific account of the facts of mind gradually detached itself, more especially in the associational doctrine of Hartley and his followers, from the general body of philosophic speculation. The thorough-going and consistent study of mental phenomena in their connexion with physiological processes (which was hastily pushed in advance of physiological science in the speculations of the materialists of last century, including Hartley) belongs to quite recent times.

§ 7. Standpoint of Psychology: characteristics of Mind. After this brief historical introduction to the subject, we

It is well remarked by Maine de Biran that, owing to this fundamental difference in outer and inner observation, men of the world and physical inquirers are rarely apt in philosophical discussion. Oeuvres inédites, i. p. 87.

DISTINCTIVE MARKS OF MIND.

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may proceed to consider more at length the standpoint and the province of the science of psychology as it is now understood.

(a) Negative characteristics. As already implied, the phenomena with which psychology deals are distinguished by clear marks or characteristics from physical phenomena. In this fact lies the main peculiarity of the science. We have now to attempt to define these characters more precisely.

In the first place, then, what we call a mental state or process is marked off negatively from material objects and their actions by the absence of certain properties. All phenomena of the external world are phenomena in space, and have the space-attributes of position and extension. The phenomena

of the internal world are said to be in time only, and not in space; or, in other words, to be unextended. An idea does not arise in some point of space, nor does it present a surface made up of points lying side by side, one to the right of the other, and so forth. Our perceptions, recollections, longings, and efforts are events or processes in time; and the relations between their several elements are time-relations-that is, concomitance and succession.

This negative characteristic insisted on by Kant is clear enough in most cases. What makes it ever doubtful is the fact that the properly psychical phenomenon is apt in certain cases to be confused with a physical fact. Thus our so-called bodily sensations are apt to be thought of as arising at a definite locality in the body. This, however, as will be seen by and by, is an illusion involving a confusion between a mental fact, a sensation, and a physical fact, viz., an action in a particular region of the body which is known to occasion the sensation. So, too, our perceptions of external objects are not extended as perceptions, i.e., as mental operations. It is not the sight of a tree, but the tree, i.e., the external thing or object seen, which has position in space, an extended surface, and so forth.

(b) Positive characteristics of Psychical Phenomena: meaning of "facts of consciousness". If now we ask by what positive marks psychical phenomena are distinguished from physical, the

1 The reader must carefully note that the terms internal and external in this connexion do not involve space relations. A tree is not outside a mind that perceives it in the same way as the tree is outside an adjoining house.

2 This negative determination of psychical phenomena is emphasised by Dr. Bain, The Senses and the Intellect, Intr. ch. i. I. It is criticised by Brentano, Psychologie, p. 113, and by Dr. Ward, Encyclopædia Britannica, art. “Psychology," P. 38.

answer is less easy. To define the common attributes of mind presupposes that we have made a careful examination and comparison of all the main varieties of its manifestations. Hence it would naturally come at the end rather than at the beginning of our inquiry.

There is, nevertheless, one characteristic involved in our common way of speaking of mental phenomena which may be referred to at once. We have already described this region of phenomena in a measure by calling it the inner world of conscious experience, or the region of subjective, as distinguished from objective fact. What, it may be asked, is involved in this use of the term consciousness or subjective experience?

The least inspection of the phenomena here classed together as "mental states " discloses the fact that they are not isolated events. A perception of colour, a feeling of wonder, does not occur by itself, but only as a member of a continuous series or flow of events which together constitute somebody's conscious experience. The very idea of such a conscious experience implies that the variety of mental phenomena which form its elements are somehow capable of being brought into relation one to another and grouped as a unity. This applies to the very lowest conceivable types of consciousness in the animal world. We only attribute mind to an animal when we see the rudiments of such organising activity in the weaving together of a number of sense-elements into what we call experience.

In the case of the human mind we have as the full outcome of this relating or organising process the bringing together of present and past mental events in what is known as "SelfConsciousness". Here a multitude of psychical elements are at once distinguished and combined by being referred to a common centre, self. Hence the practice among psychologists of marking off psychical from physical phenomena as "states of consciousor as states of which the subject or ego is immediately conscious as its own.

"

Here then we seem to have a real differentia or distinguishing mark of psychical phenomena. The actions of a material body are not distinguished and arranged by that body. Still less are they known to it as its own actions. Our feelings, thoughts, and desires, on the other hand, are directly apprehended, or capable of being apprehended, as ours.