The concept of the absolute grows out of the logical task which is incumbent on reason, i.e., inference, and it may be best explained from this as a starting point.  In the syllogism the judgment asserted in the conclusion is derived from a general rule, the major premise.  The validity of this general proposition is, however, itself conditional, dependent on higher conditions.  Then, as reason seeks the condition for each conditioned moment, and always commands a further advance in the series of conditions, it acts under the Idea of the totality of conditions, which, nevertheless, since it can never be given in experience, does not denote an object, but only an heuristic maxim for knowledge, the maxim, namely, never to stop with any one condition as ultimate, but always to continue the search further.  The Idea of the unconditioned or of the completeness of conditions is a goal which we never attain, but which we are continually to approach.  The categories and the principles of the understanding were constitutive principles, the Ideas are regulative merely; their function is to guide the understanding, to give it a direction helpful for the connection of knowledge, not to inform it concerning the actual character of things.

Since reason is the faculty of inference (as the understanding was found to be the faculty of judgment), the forms of the syllogism perform the same service for us in our search for the Ideas as the forms of judgment in the discovery of the categories.  To the categorical, hypothetical, and disjunctive syllogisms correspond the three concepts of reason, the soul or the thinking subject, the world or the totality of phenomena, and God, the original being or the supreme condition of the possibility of all that can be thought.  By means of these we refer all inner phenomena to the ego as their (unknown) common subject, think all beings and events in nature as ordered under the comprehensive system of the (never to be experienced) universe, and regard all things as the work of a supreme (unknowable) intelligence.  These Ideas are necessary concepts; not accidental products nor mere fancies, but concepts sprung from the nature of reason; their use is legitimate so long as we remember that we can have a problematical concept of objects corresponding to them, but no knowledge of these; that they are problems and rules for knowledge, never objects and instruments of it.  Nevertheless the temptation to regard these regulative principles as constitutive and these problems as knowable objects is almost irresistible; for the ground of the involuntary confusion of the required with the given absolute lies not so much in the carelessness of the individual as in the nature of our cognitive faculty.  The Ideas carry with them an unavoidable illusion of objective reality, and the sophistical inferences which spring from them are not sophistications of men, but of pure reason itself, are natural misunderstandings from which even the wisest cannot free himself.  At best we can succeed in avoiding the error, not in doing away with the transcendental illusion from which it proceeds.  We can see through the illusion and avoid the erroneous conclusions built upon it, not shake off the illusion itself.