PeroK said:
First, I have no authority. I'm just an amateur who has taught myself physics during my retirement.
Well, whatever you and I are in real life, in this context you’re in a position of authority with respect to me, as you’re a respected member of the community who’s giving me help and I’m a relatively new member with little questions asked and no help given on the forum. But that’s besides the point, you’re right I don’t think it’s relevant.
PeroK said:
How you interpreted that as condescending is beyond me.
Comparing me to a stubborn student that refuses to accept that authority could be wrong and doesn’t have confidence in his own positions feels quite condescending to me: the underlying assumption being that I lack critical thinking skills and I mindlessly follow what other people tell me is true, without questioning. Maybe this is a harsh read and you didn’t mean this, but this is what it felt like.
PeroK said:
Third I never used the word "beginner". I just said students. There were not all beginners, which is very much my point.
Fair, nothing to say here, my bad.
PeroK said:
Fourth, it was definitely not out of context. The context of this thread is that the book appears to be asking you to prove something that is clearly not generally true. And by post #9, you were still unsure:
That looks like you were still very reluctant to accept that the book had a simple omission.
It wasn’t clear to me at all that it could not be true. Just because one can prove a statement by making it more specific by adding an extra assumption, it doesn’t mean that it can’t also hold in general without that assumption: it could just mean that there is a more general proof you’re taking a specific case of (A+B -> C doesn’t mean that A -> C is wrong). I kept asking you if *you* thought that the book was wrong because you alluded to it, and I was open to the possibility. But I didn’t have any good reason to think that it could be wrong at that time.
Then, after you made me think about that easy counterexample, I immediately became convinced and didn’t insist that the book couldn’t possibly be wrong.
Anyways, this discussion isn’t very productive, I understand your intention wasn’t to pass as condescending. It’s just what I felt like, and I explained why, and wanted to clarify that no, I didn’t already think that there was a mistake before becoming convinced. I don’t think expressing how I felt and clarifying my thoughts is unpolite or rude, as Vanadium said. If you say you weren’t being patronizing and just wanted to give genuine advice, I believe you. Thanks again for your help!