A Libertarian case for supporting abortion rights even if you believe that "life

[True Federalist (진정한 연방 주의자)]

This libertarian argument does at least provide a rationale for allowing otherwise unallowed abortions in the case of rape and incest that many favor.  A woman who has engaged in voluntary sexual activity can be said to have engaged in a contract that any resulting fetus would be carried to term.  However in the case of rape and incest, no valid contract was entered into because of the lack of consent.

It's a rather cold argument for allowing such abortions but at least it can be logically supported.

[True Federalist (진정한 연방 주의자)]

This libertarian argument does at least provide a rationale for allowing otherwise unallowed abortions in the case of rape and incest that many favor.  A woman who has engaged in voluntary sexual activity can be said to have engaged in a contract that any resulting fetus would be carried to term.  However in the case of rape and incest, no valid contract was entered into because of the lack of consent.

It's a rather cold argument for allowing such abortions but at least it can be logically supported.

That's a rather stupid argument for a pro-life position, because it adopts a variant of Rousseauianism, of all things, to defend an allegedly libertarian point-of-view. Contract law ends when there is no contract signed; to attempt to be vague on this issue is to accept the "social contract", which is anti-libertarianism incarnate.

The argument I put forth does not rely upon Rousseau but rather Proudhon.  Nor does it address the issue of whether abortion should or should not be available, but rather the narrower issue of whether when abortion is restricted, a justification can be made for having those restrictions be lessened when rape or incest is involved.

[True Federalist (진정한 연방 주의자)]

That hardly matters, because it's still positing a contract where no such contract actually exists. Again, it's a case of libertarian legalism, admitting the utility of coercion to achieve a desired end: "we'll just say you signed a contract when you had sex because.... because!"

Unless an actual contract is signed or verbally assented to, no contract exists. It still seems to me like you're intentionally looking for a way to keep two fundamentally opposing philosophies unified.

If one does not accept the premise then one has to fall back on the definition of "human life" argument, in which case if the fetus is a human life, then the state has every duty and obligation to prevent its death unless necessary to save the life of the mother and if it is not a human life then it has no business being involved in the decision to abort.  In either case, whether rape or incest was involved is irrelevant.

(If you believe that the state has no business in deciding what constitutes a human life and/or protecting human lives then you aren't a libertarian but an anarchist who thinks that at most murder is something to be dealt with in the civil courts [assuming there are any courts whatsoever.])