"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.)