>And "commonplace" is certainly not synonymous with "common sense". That has a different meaning altogether.
I notice a tendency to debate via mere contradiction - like Monty Python.
M: I came here for a good argument. A: No you didn't; no, you came here for an argument. M: An argument isn't just contradiction. A: It can be. M: No it can't. An argument is a connected series of statements intended to establish a proposition. A: No it isn't. M: Yes it is! It's not just contradiction. A: Look, if I argue with you, I must take up a contrary position. M: Yes, but that's not just saying 'No it isn't.' A: Yes it is! M: No it isn't!
Well, I say commonplace is common sense - so there! A: No it isn't! M Yes, it is!
Regardless, Richard Dedekind is here appealing to common sense, plain as day. Know what "plain as day" means?