In the case of the philosophy of natural science the 'absurdum' can only be that our perceptual knowledge has not the character assigned to it by the theory.

If our opponent affirms that his knowledge has that character, we can only--after making doubly sure that we understand each other--agree to differ.

Accordingly the first duty of an expositor in stating a theory in which he disbelieves is to exhibit it as logical.
It is not there where his trouble lies.
Let me summarise the previously stated objections to this theory of nature.

In the first place it seeks for the cause of the knowledge of the thing known instead of seeking for the character of the thing known: secondly it assumes a knowledge of time in itself apart from events related in time: thirdly it assumes a knowledge of space in itself apart from events related in space.

There are in addition to these objections other flaws in the theory.
Some light is thrown on the artificial status of causal nature in this theory by asking, why causal nature is presumed to occupy time and space.