Im learning about predicate logic from this textbook and I stumbled upon something that really confused me (both in phrase and in the contradiction I think I found).
On page 64 there is a sentence "There is someone who likes everyone who likes everyone that he likes". The purpose is to break it down to be put into predicate logic. Ok, confusing, but paraphrasing "There is a person who likes all individuals, such that the individual likes all the same people that he also likes". But what if the individual didn't like themselves? Everyone else the individual likes the same as the person but if they didn't like themselves this would be a contradiction. The person likes the individual, but the individual didn't like themselves, then they don't like all the same people. But if the person now doesn't like the individual, they now like all the same people so the person likes the individual. Am I not understanding something, or is this really a very confusing paradox?
What you show is that it is not possible for this person not to like themselves. That is not a paradox, however ... it just means that apparently this person must like themselves.
That is, there is indeed a contradiction if this person does not like themselves. But there is no contradiction if this person does like themselves.