That the truth of one proposition follows from the truth of other propositions, we perceive from the structure of the propositions. The method of inference is to be understood from the two propositions alone. Only they themselves can justify the inference.
All inference takes place a priori.
From an elementary proposition no other can be inferred. 5.135 In no way can an inference be made from the existence of one state of affairs to the existence of another entirely different from it. There is no causal nexus which justifies such an inference.