“shape” of the world outside the mind. Kant argued instead that objects conform
to the mind: that how one experiences the world is a result of the way the mind oper-
ates. Knowledge is a result of human understanding applied to sense experience.
Space and time are two ways the mind operates. They are not “objects” in the
world, derived from sense experience; rather, they are the precondition for our
having sense-experience at all: They are the a priori(meaning “known indepen-
dently of sense perceptions,” “indubitable”) foundations of sensibility. Space and
time must be presupposed in order to have experience at all.
Kant goes on to consider the a priorifoundations of human understanding. He
argues that there must be categories of the mind, such as causality and substance,
that unify our perceptions. These categories are not found in sense experience;
they are innate structures of the mind and the necessary conditions for having any
knowledge at all. Without these categories, the world of experience would be
utterly chaotic and unknowable.
Of course, this knowledge is only a knowledge of things as we experience them
in the “phenomenal world.” The way things really are, apart from our experience
of them, the “noumenal world” of the “things-in-themselves,” is not available to us
by pure reason. This, according to Kant, means that we cannot have knowledge of
God, the world, or even the substantial self. But rather than letting this end in
Humean skepticism, Kant suggests that these three “ideas of reason” (God, world,
self) stimulate and unify knowledge. They point beyond themselves to possibilities
in the noumenal world that pure reason cannot reach. As long as we do not think
that we have real knowledge of their objects, these three ideas of reason serve a
useful purpose.
Turning to moral theory, Kant develops a “deontological,” or “duty-based,”
theory of morality. An action is good not because it produces consequences such
as pleasure or happiness, but because it is done out of duty by a good will. To
establish what a person’s duty is, Kant develops the “categorical imperative.” In
the Foundations of the Metaphysics of Morals,Kant discusses several versions of
this imperative, the most important of which is this: “Act only on that maxim
whereby you can at the same time will that it should become a universal law.” The
short essay, “On a Supposed Right to Lie From Altruistic Motives,” shows some
of the implications of Kant’s deontological moral theory.
Although Kant is best known for his work in epistemology and ethics, he wrote
on many topics. His earlier essay “Idea for a Universal History with Cosmopolitan
Intent” (1784) is an example of Kant at his nontechnical best. Here the Königsberg
recluse shows himself as a brilliant citizen of the world when he introduces the
idea of a League of Nations:
By means of wars and the high tension of never relaxed armaments for these wars,
and by means of the distress which every nation must thus suffer, even during
times of peace, [Nature] drives man at first to imperfect attempts, but finally, after
many devastations and disturbances and even exhaustion of all powers, she drives
toward a situation which reason might have anticipated without so many sad expe-
riences: Men leave the lawless state of savages and enter a League of Nations.
Thus every state, including the smallest, can find a guarantee for its security and
its rights, not in its own power or in its own views of what is just, but in this great
League of Nations.