Experimental Reason, Appearances, Freedom

According to Kant, 'nature' is a system of events, each of which is an appearance.  However, to cause to occur and to cause to appear are not equivalent.  For, the latter, but not the former, presupposes the existence of a perceiver to which an event might appear.  In other words, to cause to appear can  be onlypurposeful, and, hence, only extra-natural, i. e. only free causality, in Kant's doctrine.  Now, Experimental Reason produces not merely an event, but evidence, i. e. an appearance.  Hence, Experimental Reason entails free causality.