C. G. Jung distinguished eight basic psychological types: “attitudes” of introversion or extraversion in combination with “conscious functions” of thinking, intuition, sensation, and feeling. So the eight basic types are introversion combined with thinking, intuition, sensation, or feeling, and extraversion combined with one of these conscious functions. Each individual, whether an introvert or an extravert, will “differentiate” (i.e. favor) one conscious function which will invariably be complemented with a second conscious function; so that an introvert, for example, might favor thinking complemented with intuition.
It is quite obvious that Hamlet is an extreme example of an introvert who favors thinking. He tells Rosencrantz: “O God, I could be bounded in a nut shell and count myself a king of infinite space.” His many soliloquies not only show that he is a deep thinker but that he enjoys solitude (the chief characteristic of an introvert, along with the kind of dislike of large social gatherings which Hamlet displays in the second scene of the opening act). The fact that Hamlet has been a student at Wittenberg for so many years—and still wishes to go back for further study--may partially explain why he is so addicted to thinking, although Jung tells us that introversion and extraversion are not learned or conditioned but congenital.
Thinking is Hamlet’s main conscious function—but what about his complementary conscious function? There are only two possibilities: intuition and sensation. Jung reiterates that feeling cannot be a complement to thinking, and vice versa. (Ophelia, whom Jung might diagnose as an extravert with feeling as her primary conscious function and intuition as the complementary function, tells her father “I do not know, my lord, what I should think” and later tells Hamlet “I think nothing, my lord.”) A thinking person has feelings but will repress them. Hamlet is obliged to murder King Claudius, but it takes rage—the kind exhibited by Laertes when he assaults Claudius—to commit a murder, and Hamlet’s obsessive thinking overrides his feelings. He suspects there is something wrong with him—cowardice perhaps? But the more he analyzes himself, the more he represses his feelings. He cannot think and feel at the same time—just as a person whose main conscious function is feeling cannot feel and think at the same time. (Which might explain why the emotion-charged Laertes is so easily managed by the wily Claudius, whom Jung might diagnose as an extravert whose conscious function is thinking complemented with sensation.)
Coleridge said that Hamlet thinks too much. This is perfectly true. Jung’s Psychological Types helps to put a finer point on it. If Hamlet starts thinking about how much hates Claudius, he cannot feel that hatred because his thinking takes over his feeling. As Coleridge says: “…this very speculation on his own infirmity only affords him another occasion for indulging it.” This is notable in the soliloquy in which Hamlet begins by reflecting on all his reasons for killing Claudius and ends up devising a complicated plot to stage a play intended to make the king reveal his guilt. When Hamlet finally kills Claudius, it is characteristically without having had time to think. Hamlet for a short while enjoys the freedom of acting on his feelings.