The mental process of interpreting what is perceived. (Compare feeling.)
In Jung’s model of typology, thinking is one of the four functions used for psychological orientation. Along with feeling, it is a rational function. If thinking is the primary function, then feeling is automatically the inferior function.
Thinking, if it is to be real thinking and true to its own principle, must rigorously exclude feeling. This, of course, does not do away with the the fact that there are individuals whose thinking and feeling are on the same level, both being of equal motive power for consciousness. But in these cases there is also no question of a differentiated type, but merely of relatively undeveloped thinking and feeling.["General Description of the Types," CW 6, par. 667.]
As a process of apperception, thinking may be active or passive.
Active thinking is an act of the will, passive thinking is a mere occurrence. In the former case, I submit the contents of ideation to a voluntary act of judgment; in the latter, conceptual connections establish themselves of their own accord, and judgments are formed that may even contradict my intention. . . . Active thinking, accordingly, would correspond to my concept of directed thinking. Passive thinking . . . I would call . . . intuitive thinking.["Definitions," ibid., par. 830.]
The capacity for directed thinking I call intellect; the capacity for passive or undirected thinking I call intellectual intuition.[Ibid., par. 832.]