In the Second Analogy, Kant also explains what makes it possible to infer the objective succession from the subjective succession. He argues that objective succession must stand under a causal rule. The subjective order of perceptions is always successive, but we cannot immediately infer objective succession from the subjective succession. To make this inference possible the object's states must be subject to a rule that determines them as successive. Kant mentions this requirement in the following paragraph.
“must therefore consist in the order of the manifold of appearance in accordance
with which the apprehension of one thing (that which happens) follows that of
the other (which precedes it) in accordance with a rule. Only thereby can I be
justified in saying of the appearance itself, and not merely of my apprehension,
that a sequence is to be encountered in it.” (A193/B238)
Then, he characterizes this rule as something that always and necessarily follows. Also, this rule must make the
progress from a given time to the determinately following one possible, and necessarily relate every perception to something else in general that precedes. Accordingly, the successive states of an object must include a relation of condition to conditioned, i.e., that of the causal dependence of successive states on a cause6; consequently, the rule is a causal rule. Kant explains the argument for the claim that we can have knowledge about objective succession if the successive states of the object stands under a causal rule in the following passage.
“In accordance with such a rule there must therefore lie in that which
in general precedes an occurrence the condition for a rule, in accordance with which this occurrence always and necessarily follows; conversely, however, I cannot go back from the occurrence and determine
(through apprehension) what precedes. For no appearance goes back
from the following point of time to the preceding one, but it is related
merely to some preceding point or other; on the contrary, the
progress from a given time to the determinately following one is necessary. Hence, since there is still something that follows, I must necessarily relate it to something else in general that precedes, and on which it
follows in accordance with a rule, i.e., necessarily, so that the occurrence, as the conditioned, yields a secure indication of some condition,
but it is the latter that determines the occurrence.” (A194/B293)
There are two possible interpretations for the causal rule: first, any rule that includes causal dependence, and second, a rule that necessarily determines in a given situation which state happens next. The first one is what the weak reading would suggest, which reduce the causal law to “Every event has a cause,” and the second one is the strong reading and indicates that “events type A are the cause of event type B.”
Beck distinguishes between the weak and the strong reading, in his 1978 paper. He...