General Nature of Thought.—The processes marked off by the psychologist as thinking or thought constitute the highest stage of intellectual elaboration (intellection). By taking our concrete percepts and resolving them into so many abstractions, (qualities or attributes of things, relations between things,) we are enabled to carry out the process of cognition to the furthest point of unification. As long as we view a particular object, or an event, alone apart from other things, we merely apprehend it. But when we bring it into relation to kindred things we comprehend it. Thus, we comprehend the tiger by classing it with other members of the feline group. So we comprehend or understand the movement of the steam-engine by assimilating it to the more familiar action of the steam in the kettle in forcing up the lid.
Like imaginative production thinking is nothing but the sum of processes of separation and combination, carried out on sense-material. But in this case the elaborative processes assume a new and peculiar form. It is one thing to build up a pictorial image as the poet does, another thing to elaborate an abstract idea, such as the scientific notion of force, fulcrum, and so forth. We must now try to investigate more thoroughly the nature of this thought-elaboration.
Thought as Activity.—It is evident that the processes here roughly described are active processes, that is to say they involve a special exertion of the forces of attention. In perception, reproduction, and constructive imagination, this active factor is at work. But it is only in thought proper that this activity becomes fully developed. To think of a particular attribute in an object, say the color of a rose, is as we all know a conscious effort or strain. A child first called upon to think about abstract qualities, and the general relations of objects finds the operation difficult and fatiguing. All thinking is in truth an exercise of the higher form of attention, viz. volitional concentration of consciousness. We only think when we have some purpose as the discovery of the likeness or difference among objects, and such a purpose only develops itself as the individual and the race attain a certain measure of development or culture. The child and the savage, like the animal, get on very well without thinking. And even a large proportion of civilised adults think only in an occasional and rudimentary way. Thought is thus in all cases a kind of artificial activity sustained only for short periods and under the stress of impulses or motives which belong to a high stage of intellectual and moral development.
The high degree of activity in thought presumably involves a special amount of that muscular strain which forms the sensuous base of the attitude of attention. To think is thus to concentrate consciousness by aid of energetic motor adjustments. These include the innervation of certain muscles, more particularly those by which movements of the eyes and head are carried out. To think is to keep certain ideational elements in persistent consciousness, and this is probably effected in part at least by an energetic and sustained innervation of particular groups of muscles. To this it may be added that since as we shall see presently all thinking is bringing together in their relations a number of ideational elements, the muscular activity in the case is of a specially difficult kind. Such special muscular efforts would probably effect a cutting off of other elements and so subserve that severe narrowing of consciousness which is so marked a feature in thought.
Directions of Thought-Activity.—This thought-activity may be viewed as having two aspects or as following two directions, which it may be well to view apart, even though, as we shall presently see, they are inseparable aspects of one process. Just as all intellectual elaboration is at once differentiation or separation and integration or combination of what is differentiated, so thought itself is but a higher development of each phase.
a) Analysis, Abstraction.—First of all, then, thought may be viewed as a carrying further and into higher forms the process of differentiation or separation of presentative elements by means of isolating acts of attention. Thus on selectively considering the color of a rose, or the form of a crystal, we are it is evident differentiating what is given in perception as a complex into a number of parts, and rendering one of these specially prominent and distinct. Such thought-separation is commonly spoken of as Analysis, i. e. the taking apart of what is conjoined in a whole, and also as Abstraction or the withdrawal of attention from what is for the moment irrelevant and confining it to one particular point, feature, or quality (Latin ab or abs, and traho).
Here it is evident a special attitude and effort of attention is required. It is one thing to note carefully a presentative complex just as it is, another thing to single out some element of this and fix the attention on it. The peculiar difficulty of this analytic attention is due to the firm coherence of the complex. The child cannot see the color of the orange just because the orange as a whole stands in the way. Hence this analytic attention is abstraction in the fullest sense, that is a deliberate turning aside from what stimulates or attracts this attention at the moment.
Such abstract singling out of an element may be supposed to involve a special modification of the muscular adjustment in attention. Hence perhaps the comparative ease with which we can single out for observation locally distinct features of an object, to which correspond different movements of the sense-organ. On the other hand the great difficulty of mentally separating the color from the form of an object may arise from the common element in the muscular adjustments concerned.
The nature of this process of analysis or abstract attention is best seen in those comparatively simple operations in which an actual presentation-complex as a group of tones or colors is being analysed. The carrying out of such a process of analysis is aided by certain conditions objective or external, and subjective or internal. Thus it is found that the closer the degree of the complication the more difficult the isolating fixation. Thus while it is comparatively easy to attend to one detail of color in an object locally separated from other color-details it is exceedingly difficult to attend to the brightness or the degree of saturation of a color apart from the quality of the tone itself. In the case of tone-masses, again, it is found that certain combinations, more especially that of the octave, are difficult to distinguish because of the tendency in this case to fusion.[95]
[95] This is Stumpf's explanation. See his account of the different degrees of fusion. Tonpsychologie ii. p. 65, and p. 127 et seqq.