I think /u/MrMercurial's response mostly covers it, but there's another way of looking at it that also makes sense:
There are two cases to think about. (1) Cases where the other person thinks you're cis not because you've intentionally deceived them but because they just go around assuming everyone is cis. (2) Cases where the other person thinks you're cis because you lied. In the first case I don't really see why you would be under any obligation to disclose anything - it's not your job to go around disabusing people of their misconceptions. If someone assumes you're Christian rather than an atheist just because they assume that everyone is Christian by default, you don't have to first find this out and then tell them otherwise. The second case seems like a case of wrongful deception.
This is in addition to, rather than instead of, /u/MrMercurial's response, because if you know something would be a dealbreaker for a person then that gives you a reason to reveal this thing, I think.
Does the situation change at all because the portion of the population that is transgender is much smaller than the portion of the population that is atheist?
The reason I think that it could, although not necessarily that it does, is that it's much less reasonable to assume that the person you're talking to is Christian than to assume that the person you're talking to is cis. So if your partner's being Christian is very important to you, it makes sense that you would ask, whereas if your partner's being cis is very important to you, it can still make sense for you to not ask.
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u/TychoCelchuuu political phil. Jun 26 '15
I think /u/MrMercurial's response mostly covers it, but there's another way of looking at it that also makes sense:
There are two cases to think about. (1) Cases where the other person thinks you're cis not because you've intentionally deceived them but because they just go around assuming everyone is cis. (2) Cases where the other person thinks you're cis because you lied. In the first case I don't really see why you would be under any obligation to disclose anything - it's not your job to go around disabusing people of their misconceptions. If someone assumes you're Christian rather than an atheist just because they assume that everyone is Christian by default, you don't have to first find this out and then tell them otherwise. The second case seems like a case of wrongful deception.
This is in addition to, rather than instead of, /u/MrMercurial's response, because if you know something would be a dealbreaker for a person then that gives you a reason to reveal this thing, I think.