In all the resources that I have seen, I always find that would for conditional 2 and 3 is made up of a sentence with if-clause (or similar) and result clause (would).
But then I find many phrases like this: Nobody in their right mind would put that person on the witness stand
Is it just a type of conditional 2, but without if-clause? This makes sense in the Spanish translation, but I don't know. I have not found any resources where I explain this form of the conditional