One of the reason people believe in cause and effect is that they believe in the existence of laws of nature. But this mistakes a mathematical description of an event for an explanation. It also explains how cause and effect is tied up with necessity.
The ‘regularity’ of a succession is only a figurative expression, as if here a rule were being obeyed: it is not a fact. Likewise ‘conformity with a law’. We find a formula to express a kind of sequence that occurs again and again: doing this doesn’t mean we have discovered a ‘law’, and even less a force which is the cause of the recurrence of sequences. That something always happens thus and thus is here interpreted as if a being’s always acting thus and thus resulted from obedience towards a law or a legislator, while without the ‘law’ it would be free to act otherwise. Yet precisely that thus-and-not-otherwise might originate in the being itself, which behaved thus and thus not on the prompting of some law but as constituted thus and thus. It only means: something cannot be something else as well; cannot do first this, then something different; is neither free nor unfree, but just thus and thus. The mistake lies in a subject being invented in.
Notebook 2, autumn 1885 – autumn 1886 paragraph 142