Irrational. Not grounded in reason. (Compare rational.)
Jung pointed out that elementary existential facts
fall into this
category-for instance, that the earth has a moon, that
chlorine is an
element or that water freezes at a certain temperature
and reaches its
greatest density at four degrees centigrade-as does
chance. They are
irrational not because they are illogical, but because
they are beyond
reason.
In Jung's model of typology, the
psychological functions of
intuition and sensation are described as
irrational.
Both intuition and sensation are functions that find fulfilment in the absolute perception of the flux of events. Hence, by their very nature, they will react to every possible occurrence and be attuned to the absolutely contingent, and must therefore lack all rational direction. For this reason I call them irrational functions, as opposed to thinking and feeling, which find fulfilment only when they are in complete harmony with the laws of reason.[Ibid , pars. 776f.]
Merely because [irrational types] subordinate judgment to perception, it would be quite wrong to regard them as "unreasonable." It wouldbe truer to say that they are in the highest degree empirical. They base themselves entirely on experience. ["General Description of the Types," Ibid, par. 616.]