As a
matter of fact, however, we all assert that the water could not have come
into a boiling condition unless the generation of heat had preceded; that
in every case the fire must be there before the boiling of the water can
commence. Whence do we derive this _must_? Simply and alone from the
thought of a causal connection between the two events. Every phenomenon
_must_ follow in time that phenomenon of which it is the effect, and must
precede that of which it is the cause. It is through the relation of
causality, and through this alone, that the objective time relation of
phenomena is determined. If nothing preceded an event on which it must
follow according to a rule,[1] then all succession in perception would be
subjective merely, and nothing whatever would be objectively determined by
it as to what was the antecedent and what the consequent in the phenomenon
itself. We should then have a mere play of representations without
significance for the real succession of events. Only the thought of a rule,
according to which the antecedent state contains the necessary condition of
the consequent state, justifies us in transferring the time order of our
representations to phenomena.[2] Nay, even the distinction between
the phenomenon itself, as the object of our representations, and our
representations of it, is effected only by subjecting the phenomenon to
this rule, which assigns to it its definite position in time after another
phenomenon by which it is caused, and thus forbids the inversion of the
perceptions. We can derive the rule of the understanding which produces the
objective time order of the manifold from experience, only because we have
put it into experience, and have first brought experience into being by
means of the rule. We recapitulate in Kant's own words: The objective
(time) relation of phenomena remains undetermined by mere perception (the
mere succession in my apprehension, if it is not determined by means of a
rule in relation to an antecedent, does not guarantee any succession in
the object). In order that this may be known as determined, the relation
between the two states must be so conceived (through the understanding's
concept of causality) that it is thereby determined with necessity which of
them must be taken as coming first, and which second, and not conversely.
Thus it is only by subjecting the succession of phenomena to the law of
causality that empirical knowledge of them is possible. Witho