culties involved in
the thought of a process which begins in this way until he comes to
vindicate causality, it is only when we come to this vindication that
we realize the real nature of his deduction of the analogies, and, in
particular, of that of the first.

Kant, prompted no doubt by his desire to answer Hume, treats the
principle of causality very fully. The length of the discussion,
however, is due not so much to the complication of the argument as to
Kant's desire to make his meaning unmistakable; his account consists
mainly in a repetition of what is substantially the same argument no
less than five times. Hence it will suffice to consider those passages
which best express Kant's meaning. At the same time, the prominence of
the principle of causality in Kant's theory, and in the history of
philosophy generally, and also the way in which Kant's treatment of
it reveals the true nature of his general position, makes it necessary
to consider these passages in some detail.

Hume had denied that we are justified in asserting any causal
connexion, i. e. any necessity of succession in the various events
which we perceive, but even this denial presupposed that we do
apprehend particular sequences in the world of nature, and therefore
that we succeed in distinguishing between a sequence of events in
nature and a mere sequence of perceptions, such as is also to be found
when we apprehend a coexistence of bodies in space. Kant urges, in
effect, that this denial renders it impossible to explain, as we
should be able to do, the possibility of making the distinction in
question, which even the denial itself presupposes that we make.
Holding, with Hume, that in all cases of perception what we are
directly aware of is a succession of perceptions, he contends that it
is necessary to explain how in certain cases we succeed in passing
from the knowledge of our successive perceptions to the knowledge of a
succession in what we perceive. How is it that we know, when, as we
say, we see a boat going down stream, that there is a succession in
what we perceive, and not merely a succession in our perception of it,
as is the case when, as we say, we see the parts of a house? Hume,
according to Kant, cannot answer this question; he has only the right
to say that in all cases we have a succession of perceptions; for in
reality an answer to the question will show that the acquisition of
this knowledge involves an appeal to the principle of