6.3

Logical research means the investigation of all regularity. And outside logic all is accident.

6.31

The so-called law of induction cannot in any case be a logical law, for it is obviously a significant propositions. -- And therefore it cannot be a law a priori either.

6.32

The law of causality is not a law but the form of a law.

6.321

"Law of Causality" is a class name. And as in mechanics there are, for instance, minimum-laws, such as that of least actions, so in physics there are causal laws, laws of the causality form.

6.3211

Men had indeed an idea that there must be a "law of least action", before they knew exactly how it ran. (Here, as always, the a priori certain proves to be something purely logical.)