Here is the excerpt (which seems to have been excised from the version of the essay on Harpers' site. I got this from the version in Consider the Lobster):
In this reviewer's opinion, the only really coherent position on the abortion issue is one that is both Pro-life and Pro-choice.For someone immersed in the culture of liberal academia, it's admirable that Wallace even allows himself to reason his way to this moderate position. However, he can't quite bring himself to go all the way, possibly for fear that his exquisite reasoning has lead him to a standard, conservative, privileged, white, American, male position on an issue that liberal academic circles would be especially prone to suspecting such biases for being the true source of the conclusion, rather than the flawless reason. Indeed, a subsequent passage indicates that just such an insecurity is very likely in play in Wallace's thought.
Given our best present medical and philosophical understandings of what makes something not just a living organism but a person, there is no way to establish at just what point during gestation a fertilized ovum becomes a human being. This conundrum, together with the basically inarguable soundness of the principle “When in irresolvable doubt about whether something is a human being or not, it is better not to kill it,” appears to me to require any reasonable American to be Pro-Life.
At the same time, however, the principle “When in irresolvable doubt about something, I have neither the legal nor the moral right to tell another person what to do about it, especially if that person feels that s/he is not in doubt” is an unassailable part of the Democratic pact we Americans all make with one another, a pact in which each adult citizen gets to be an autonomous moral agent; and this principle appears to me to require any reasonable American to be Pro-Choice.
The point is that the appropriate, logical conclusion of the two Principles that Wallace has formulated is that abortion is wrong because the first Principle overrides the second. The right to life trumps the right to 'choose', and Wallace states no reason these two principles should carry identical weight, which is what he must demonstrate to conclude that an exactly centrist position is best. Additionally, the second Principle is grounded in some "irresolvable doubt" that Wallace has quietly smuggled in. Whence such doubt? The first Principle was formulated with "inarguable soundness." Presumably the doubt comes in because of the second Principle, but the second Principle can't be formulated apart from an extant doubt. Thus the second principle is circular and the real logical conclusion, when these two principles collide, is a Pro-life one.
Not to mention that this Pro-life conclusion is arrived at even while accepting Wallace's claim that a) the origin of human-being-ness question is inadjudicable and b) that the crux of the issue is human-being-ness. Neither of which are compelled by evidence. If we state the principle that destroying a unique, innocent, human life -- all of which a just-conceived embryo is necessarily -- is wrong, then issues of personhood or human-being-ness are superceded. Which only strengthens the argument for a Pro-life conclusion, which is already firmly established by the two principles.
Wallace is one hundred times more intelligent than I am, but I have the occasionally-useful advantage of never having been within 100 yards of a liberal arts or humanities department, and am entirely immune to the unfortunate political correctness that it breeds.
Interestingly, later in the essay Wallace shows that he is acutely aware of just such instances of being technically, indisputably correct about something (just as his argument in favor of Pro-life would be, were he to follow it through), but having the PC, liberal academic machinery rear its ugly head forces him to yield some ground. Not going so far as to admit he's wrong, but that he was perhaps clumsy or insensitive. All this, however, took place over the comparatively emotionally dry topic of the English language:
A vividly concrete illustration here concerns the Official Complaint a black undergraduate filed against this rev. after one of my little in camera spiels described on pages 53-54. The complainant was (I opine) wrong, but she was not crazy or stupid; and I was able later to see that I did bear some responsibility for the whole nasty administrative swivet. My culpability lay in gross rhetorical naivete. I'd seen my speech's primary Appeal as Logical: The aim was to make a conspicuously blunt, honest argument for SWE's [Standard Written English] utility. It wasn't pretty, maybe, but it was true, plus so manifestly bullshit-free that I think I anticipated not just acquiescence but gratitude for my candor.  The problem I failed to see, of course, lay not with the argument per se but with the person making it — namely me, a Privileged WASP Male in a position of power, thus someone whose statements about the primacy and utility of the Privileged WASP Male dialect appeared not candid/hortatory/ authoritative/true but elitist/high-handed/ authoritarian/racist. Rhetoric-wise what happened was that I allowed the substance and style of my Logical Appeal to completely torpedo my Ethical Appeal: What the student heard was just another PWM rationalizing why his Group and his English were top dog and ought "logically" to stay that way (plus, worse, trying to use his academic power over her to coerce her assent  ).
If for any reason you happen to find yourself sharing this particular student's perceptions and reaction,  I would ask that you bracket your feelings long enough to recognize that the PWM instructor's very modern rhetorical dilemma in that office was really no different from the dilemma faced by a male who makes a Pro-Life argument, or an atheist who argues against Creation Science, or a Caucasian who opposes Affirmative Action, or an African American who decries Racial Profiling, or anyone over eighteen who tries to make a case for raising the legal driving age to eighteen, etc. The dilemma has nothing to do with whether the arguments themselves are plausible or right or even sane, because the debate rarely gets that far — any opponent with sufficiently strong feelings or a dogmatic bent can discredit the arguments and pretty much foreclose all further discussion with a single, terribly familiar rejoinder: "Of course you'd say that"; "Easy for you to say"; "What right do you have ...?"It should be obvious how such an environment could lead one to temper his position considerably on the much more emotionally charged issue of abortion, even when possessing the indisputable truth that is uncomfortable for many in liberal academia -- especially females -- to hear or deal with.