The Question

During today’s U session with Walter Block on Abortion and Evictionism (a theory of his which you can read about here, or watch when the video of today’s session is uploaded), something clicked in my head, and I thought to ask Walter – assuming (as he does) that the fetus is in the position of a trespasser, would not the mother be estopped from taking action against it since she had trespassed in the same way, and thus given up rights in proportion to those violated?

I don’t think Walter quite answered my question (which I don’t blame him for, as it is a tricky question even as I ponder it some hours later), but I do think it warrants further thought. Before the question can be asked, the issue of whether the fetus is a trespasser must be assumed away or considered to be solved. For the purposes of inquiry, let’s do that (though for those who would like further reading on that question, I recommend the above-linked paper, the responses from Wisniewski, and the rejoinders from Block). We’ll also need to assume that the fetus is a human with rights (which is discussed further here). Please make these assumptions for the sake of this argument — I anticipate some discussion in the comments and would rather not argue about all of these things at once. We probably ought not to get into the broader question of whether estoppel is correct, either; I’d love to see someone write a good article here on the topic, if anyone is interested, but it’s a bigger question, and I’d like to pick at this particular nit because of its implications for theory (since many or most Austro-libertarians do believe in estoppel and accept the above assumptions).

This idea may be somewhat half-baked, so I’m submitting it to you all for a light peer review. I’d love to hear any problems others can see with it.

Introduction to Estoppel

Estoppel is a well-established legal theory in the common law (with parallels in the civil law) based on the idea that one’s legal claims must not contradict one’s prior actions. What this boils down to is that one may not object to an action which one believes to be acceptable as demonstrated by one’s own actions. Smith, a car thief, may not object when his own car is stolen by Jones because he has demonstrated by his thievery that he believes this to be acceptable. If, in our fictional libertarian non-state of Ruritania, Smith then brings up Jones on charges for the theft of his car, Jones may introduce evidence of Smith’s own larceny and argue that Smith is “estopped” from making such a claim.


There are three chief objections to this which may now be entering into your mind, if this is your first encounter with the theory, all of which are handily dealt with in Stephan Kinsella’s piece, Punishment and Proportionality: The Estoppel Approach: (1) Differences in conceptions of aggression, (2)  semantic challenges to the universalizability of the principle, and (3) changes in the stance of the parties toward the action in question over time. I refer you to that article if you’ve been tempted to begin commenting based on one of those.

Estopping Abortion

Artificial womb technology could obviate this questionIf, as we assume, a fetus is a human with rights and is a trespasser, then an innocent mother whose rights were being violated in this way might (and I say “might” here only because I have additional objections to the continuum problem posed by Block’s evictionism) be justified in evicting the growing child by the gentlest means possible (which, for a viable fetus, would mean life, while for an inviable fetus would mean death). But is the mother innocent? As I listened to Walter speak today, I was confronted by the seemingly obvious fact that the answer is a resounding NO! — every mother has trespassed in the exact same manner against her own mother, and is thus estopped from acting against the child! The mother has given up rights in proportion to those she herself violated, and so has no basis for complaint against her progeny. This conclusion is, of course, dependent on the  current state of technology — it could potentially change with scientific advances, but any such advance would obviate the problem at hand by allowing eviction at any stage of pregnancy without causing the death of the fetus.


If this argument is correct, then a pro-life position is the only one consistent with libertarian theory. Needless to say, that alone guarantees that many will disagree even if it is correct, much as many libertarians go out of their way to throw out everything they know about rights theory in order to justify IP.

After an admittedly short time contemplating this question, I’ve come up with two somewhat plausible counterarguments (both of which are in the end unconvincing), but both are useful only against a dialogically-founded estoppel (and may not even be effective against that), and as my theory of rights isn’t based on argumentation, I don’t find it necessary to type them out. Can anyone spot other issues with my argument?

Thanks in advance for the critique!