I like Hans Herman Hoppe's argumentation ethics, coupled with Kinsella's estoppel. It's a bit elaborate so I'll just refer you to google, but in a nutshell, it goes like this:
a) you cannot argue that you cannot argue
b) we argue about things because things are scarce (there is not infinity)
c) to argue presupposes that both parties have determined a priori, naturally, that arguing is conflict-free (and better, say, than killing)
d) conflict-free arguing assumes, then, that one is owner of your body and no violence should be inflicted on it, or else you would be killing instead of arguing
e) so since violence is not justified, logical or coherent, then this is where "rights" come from, as the result of justification, and not as its reason.
Coupled with estoppel:
You have a right to X (a thing, an action) if and only if your use of force to defend it cannot be coherently criticized. For example, if A breaks into B's home and B uses force against A, two things can happen:
a) A can claim that violence is wrong and B should not use defensive force. But this is incoherent because A is already engaged in initiatory force.
b) A can claim that violence is good, so then B should is justified is repelling force with force.
The interesting thing here is that in either case, yes or no, A is screwed: there is no way out of his dillema. But accepting violence, he can be punished and by rejecting it, he can't claim to be coherent since he is already doing it. Thus, rights exist because everything else is incoherent.
(Another, weaker approach is the classic Locke/Jefferson approach, or a more modern one by Rothbard and natural rights libertarianism; I was a natural rightist until I discovered the logic displayed above)
Hope this helps.
Manuel