Typology. A system in which individual
attitudes and behavior
patterns are categorized in an attempt to explain the
differences between
people.
Jung's model of typology grew out of an
extensive
historical review of the type question in literature,
mythology,
aesthetics, philosophy and psychopathology. Whereas
earlier
classifications were based on observations of
temperamental or
physiological behavior patterns, Jung's model is
concerned with the
movement of energy and the way in which one habitually
or preferentially
orients oneself in the world.
First and foremost, it is a critical tool for the research worker, who needs definite points of view and guidelines if he is to reduce the chaotic profusion of individual experiences to any kind of order. . . . Secondly, a typology is a great help in understanding the wide variations that occur among individuals, and it also furnishes a clue to the fundamental differences in the psychological theories now current. Last but not least, it is an essential means for determining the "personal equation" of the practising psychologist, who, armed with an exact knowledge of his differentiated and inferior functions, can avoid many serious blunders in dealing with his patients.["Psychological Typology," Ibid, par. 986.]
Jung differentiated eight typological groups: two
personality
attitudes-introversion and extraversion-and four
functions-thinking,
sensation, intuition and feeling, each of which may
operate in an
introverted or extraverted way.
Introversion
and extraversion are
psychological modes of adaptation. In the former, the
movement of energy
is toward the inner world. In the latter, interest is
directed toward the
outer world. In one case the subject (inner reality)
and in the other the
object (things and other people, outer reality) is of
primary
importance.
[Introversion] is normally characterized by a hesitant, reflective, retiring nature that keeps itself to itself, shrinks from objects, is always slightly on the defensive and prefers to hide behind mistrustful scru-tiny. [Extraversion] is normally characterized by an outgoing, candid, and accommodating nature that adapts easily to a given situation, quickly forms attachments, and, setting aside any possible misgivings, will often venture forth with careless confidence into unknown situations. In the first case obviously the subject, and in the second the object, is all-important.["The Problem of the Attitude-Type,"CW7, par. 62. ]
The crucial factor in determining whether one is
introverted or
extraverted, as opposed to which attitude is currently
operative, is not
what one does but rather the motivation for doing
it-the direction in
which one's energy naturally, and usually,
flows.
Whether a person
is predominantly introverted or extraverted only
becomes apparent in
association with one of the four functions, each with
its special area of
expertise: thinking refers to the process of cognitive
thought, sensation
is perception by means of the physical sense organs,
feeling is the
function of subjective judgment or valuation, and
intuition refers to
perception via the unconscious.
Briefly, the
sensation function
establishes that something exists, thinking tells us
what it means,
feeling tells us what it's worth, and through
intuition we have a sense of
its possibilities.
In this way we can orient ourselves with respect to the immediate world as completely as when we locate a place geographically by latitude and longitude. The four functions are somewhat like the four points of the compass; they are just as arbitrary and just as indispen-sable. Nothing prevents our shifting the cardinal points as many degrees as we like in one direction or the other, or giving them differ-ent names. It is merely a question of convention and intelligibility.
But one thing I must confess: I would not for anything dispense with this compass on my psychological voyages of discovery.["A Psychological Theory of Types,"CW6, pars. 958f.]
Jung's basic model, including the relationship between the four functions, is a quaternity, as shown in the diagram. (Thinking is here arbitrarily placed at the top; any of the other functions might be placed there, according to which one a person most favors.)

Jung believed that any one function by itself is not sufficient for ordering our experience of ourselves or the world around us; all four are required for a comprehensive understanding.
For complete orientation all four functions should contribute equally: thinking should facilitate cognition and judgment, feeling should tell us how and to what extent a thing is important or unimportant for us, sensation should convey concrete reality to us through seeing, hearing, tasting, etc., and intuition should enable us to divine the hidden possibilities in the background, since these too belong to the complete picture of a given situation.[Psychological Types," Ibid, par. 900.] Jung acknowledged that the four orienting functions do not contain everything in the conscious psyche. Will power and memory, for instance, are not included, because although they may be affected by the way one functions typologically, they are not in themselves typological determinants.]
The ideal is to have conscious access to the
function or functions
appropriate for particular circumstances, but in
practice the four
functions are not equally at the disposal of
consciousness. One is
invariably more differentiated, called the superior or
primary function.
The function opposite to the primary function is
called the fourth or
inferior function.
The terms "superior" and
"inferior" in this
context do not imply value judgments. No function is
any better than any
of the others. The superior function is simply the
most developed, the one
a person is most likely to use; similarly, inferior
does not mean
pathological but merely less used compared to the
favored function.
Moreover, the constant influx of unconscious contents
into consciousness
is such that it is often difficult for oneself, let
alone an outside
observer, to tell which functions belong to the
conscious personality and
which to the unconscious.
Generally speaking, a judging observer [thinking or feeling type] will tend to seize on the conscious character, while a perceptive observer [sensation type or intuitive] will be more influenced by the unconscious character, since judgment is chiefly concerned with the conscious motivation of the psychic process, while perception registers the process itself.["General Description of the Types," Ibid, par. 576.]
What happens to those functions that are not consciously brought into daily use and therefore not developed?
They remain in a more or less primitive and infantile state, often only half conscious, or even quite unconscious. The relatively undeveloped functions constitute a specific inferiority which is characteristic of each type and is an integral part of his total character. The one-sided emphasis on thinking is always accompanied by an inferiority of feeling, and differentiated sensation is injurious to intuition and vice versa.[A Psychological Theory of Types," Ibid, par. 955.]
Jung described two of the four functions as
rational (or judging) and
two as irrational (or perceiving).
Thinking, as a
function of logical
discrimination, is rational. So is feeling, which as a
way of evaluating
our likes and dislikes can be quite as discriminating
as thinking. Both
are based on a reflective, linear process that
coalesces into a particular
judgment. Sensation and intuition are called
irrational functions because
they do not depend on logic. Each is a way of
perceiving simply what is:
sensation sees what is in the external world,
intuition sees (or "picks
up") what is in the inner world.
Besides the
primary function,
there is often a second, and sometimes a third,
auxiliary function that
exerts a co-determining influence on consciousness.
This is always one
whose nature, rational or irrational, is different
from the primary
function.

Jung's model of typology is the basis for modern type tests, such as the Myers-Briggs Type Indicator (MBTI) and the Singer-Loomis Personality Profile, used in organizational settings.