Particular empirical laws are determined in relation to actual perceptions in the same way that effects are determined in relation to their causes under empirical laws.

In the discussion of the third Postulate Kant says that we can cognize an effect as necessary on the basis of an empirical law relating it to its cause—where the effect’s “connection with the actual is determined in accordance with the general conditions of experience” (A218/B266). Kant is suggesting, therefore, that the precise sense in which particular empirical laws themselves become necessary is that they, too, are “determined” in relation to actual perceptions “in accordance with the genera