Thank you for your long reply! I do recognize that I was pushing the discussion in a somewhat different direction, so I apologize for the lengthy diversion. I had imagined if you didn't want to go that way, you'd say less. (However, in regards to your protests that I was assuming you were doing something you weren't: I simply took you at your word. You were the one who wrote your title, right? And you did, yourself (towards the end) invite a stiffer kind of disagreement (necessarily some sort of debate) than I gave, so I inferred that this was plausibly in-bounds.)
However, I'm really confused by the sentiment I quoted above. When you go to the grocery store, other people are deciding on what truth for every item: this thing is a banana, and it costs $0.89/lb (if you're in the U.S., let's say). Furthermore, whenever you, say, buy a car, apply for college, get on a plane, etc., other people absolutely decide that you are the same you as you were before, and if you decide you're someone else, or cargo rather than a person, or whatever, that "truth" of yours doesn't count.
What is the point of talking about logic if the results are pointless because everyone decides to give their own truth values for everything? (All discussion then just becomes: "Whoa, look at this reeeeeally big truth table I made!") How can you tell the vegan that they can't just declare meat to be unhealthy and be done with it, if that's their truth?
Furthermore, some of our biggest advancements in fairness in society have come exactly because we do decide what is true and what is not--it's not all a big grab-bag of mutually contradictory opinions, where the strong get to inflict their favorite truth on the weak (even if there is still too much of that).
Giving up objective truth doesn't make one humble, it enables unbridled arrogance: I feel am right and nobody can deny my feeling. What makes one humble is doubt: am I right? Could I be wrong?
With regards to other people, what makes one humble is the recognition that there is a reality of what other people think and feel, and only they have direct access to it. If you deny that reality--either by thinking they don't have a reality, or that you can actually know precisely what they're thinking and feeling--then there is little point to care what they say. It's entirely reasonable for us to decide that is the real state of affairs (we have extremely good evidence) and insist that other people act accordingly (hopefully believe it too, but we also know that even if our decisions are justified, they're not actionable: we can't force a change in what they think, just explain what they should think, ask for different behavior, and invoke consequences should they behave in too egregiously of an anti-social way).
Anyway, again, thank you for the reply.
(P.S. By "semiotics" are you not meaning just the broadening of the idea of linguistics, but the philosophical tradition of e.g. Pierce? I'm not sure broadening is necessary, but some familiarity with theories of meaning and word-meaning especially are helpful in untangling the "what is a woman" debacle. People leap to propositional definitions, which are easy to convey verbally but a poor match to how most things seem to be represented conceptually (largely based on prototypes plus conventions around disambiguating certain boundary cases--I think we've come a long enough way from Rosch's initial insights to be pretty sure this is largely correct, and very very sure that the propositional model is not what is usually going on). Everyone ends up sounding like an idiot when they fumble around with propositional definitions, especially when they announce an arbitrary boundary and then try to insist that their (arbitrary, human-constructed) boundary couldn't possibly go anywhere else, despite being faced with multiple blatant counterexamples.)
(P.P.S. I'm not sure why you say I think sex is a clear-cut thing, if by that you mean that sexual differentiation in humans results in two cleanly separable phenotypes 100.000% of the time. It obviously doesn't. If you were to draw a line from the two most densly-populated parts of phenotype space ("typical man", "typical woman"), you'd find examples all along that axis--not many, in some places, but you'll find them. And you'll find them weirdly far away from the axis, too. Biology is messy. What does this have to do with my argument, though? You don't decide your biology (though some types of intentional interventions are possible); you and society together do get to decide the role you play that's compatible with the biology.)
(P.P.P.S. I don't see why you're complaining about me bringing up Atlantis and Tom Cruise when you added "the world". That's absolutely stuff about the world. If you'd left it at biology, I'd have kept it there. Again, I'm just taking you at your word. The meta-point is that it's important to say what you mean unless you have the most favorable same-thinking audience possible and you explicitly used a title suggesting that this wasn't the case.)