¹ See, for example, Michael, Tooley, ‘Abortion and Infanticide’, The Problem of Abortion, ed. Susan, Dwyer and Joel, Feinberg, 3rd edn. (Belmont, CA, 1996), pp. 40–58Google Scholar.

² For Singer's treatment of anencephaly, see Practical Ethics, 2nd edn. (New York, 1993), pp. 86, 204, and 342.

³ See Singer's Practical Ethics, p. 153 and Boonin's A Defense of Abortion (New York, 2003), pp. 46–9.

⁴ For other treatments of the acorn-oak tree example, see William Cooney, ‘The Fallacy of All Person-denying Arguments for Abortion’, Journal of Applied Philosophy 8 (1991), p. 162, and Phillip E. Devine, Ethics of Homocide (Notre Dame, 1990), p. 52.

⁵ The ‘President example’ is usually framed as a question of whether a six-year-old Jimmy Carter had the right to command the armed forces since he was even then a potential President of the United States. It is time that we philosophers update our example, though. For other treatments of the President example, see Paul D. Feinberg, ‘The Morality of Abortion’, Thou Shalt Not Kill: The Christian Case against Abortion, ed. Richard L. Ganz (New Rochelle, NY, 1978), pp. 127–49, and Burleigh T. Wilkins, ‘Does the Fetus Have a Right to Life?’, Journal of Social Philosophy 24 (1993), pp. 123–37.

⁶ See The Ethics of Killing (New York, 2002), p. 267.

⁷ This quote appears on p. 267 of Ethics of Killing. And it actually does not appear in McMahan's treatment of the argument from potential, which occurs on pp. 302–29. But McMahan makes the same point, in just a less easily quotable way, in his treatment of the argument from potential. See pp. 306 and 308.

⁸ Note that these ‘all things being equal’ and ‘tend to believe’ phrases are intended to acknowledge that there might be exceptions to the general rule that the more valuable we think something is, the more wrong we think it is both to deliberately terminate its actual existence and to deliberately prevent it from becoming actual. For example, in the case of abortion, we might not condemn one's preventing a potentially valuable person from becoming actual if the potential person in question was the result of rape. This article, however, will not pursue this sort of exception to the IPV-Principle – concentrating its efforts on other objections below.

⁹ See Ethics of Killing, pp. 306 and 308.

¹⁰ It seems to be Boonin's notion of ‘existence value’ that McMahan has in mind when he speaks of ‘instrumental value’. McMahan, for example, states: ‘To the extent that it is good or desirable that new people should exist with lives worth living, the early fetus's potential is instrumentally important’. And McMahan argues that on this conception of value, one's opposing early abortions would commit one to opposing contraception. See Ethics of Killing, p. 306.

¹¹ Three points are worth noting here. First, Boonin himself acknowledges that it only makes sense to speak of something's integrity value if it already exists. For Boonin speaks of ‘the kind of integrity that you and I have, given that we do exist’. See A Defense, p. 42. Second, Boonin's treatment of the acorn-oak tree example confirms that we must adopt his notion of existence value in this discourse, simply addressing the objections that this notion elicits as they arise in the course of our discussion. When Boonin discusses acorns and oak trees, after all, his controlling question is: What is ‘wrong about destroying an oak at a certain point in time . . . including when it was a budding acorn’ (emphasis added)? See A Defense, p. 43. The very notion of destroying something, however, presupposes that it exists. Moreover, the notion of destroying ‘something when it was something’ presupposes that the latter something existed as the former something at the time of its possible destruction. Such presuppositions therefore must be avoided in a discourse on the alleged difference between terminating the existence of something of value and preventing something of value from coming to exist in the first place. Third, Boonin's project in A Defense is to show that the abortion opponent's own views naturally lead to the conclusion that abortion is at least sometimes justified. And Boonin takes the ‘critic of abortion’ to hold that integrity value is the sort of value that applies to persons. This article, by contrast, does not purport to lead one from the views of an abortion critic to those of an abortion defender. So there will be no principled reason for us to eschew assessing persons in terms of ‘existence value’, so long as we address the relevant objections to this view as they arise in the course of our discussion.

¹² See Philosophy and Public Affairs 1 (1971), pp. 47–66.

¹³ Boonin raises this issue; see A Defense, p. 50. See, also, Stephen, Schwarz, The Moral Question of Abortion (Chicago, 1990), p. 83Google Scholar.

¹⁴ Code 2080 of California's Fish and Game Code states: ‘No person shall import into this state, export out of this state, or take, possess, purchase, or sell within this state, any species, or any part or product thereof, that the commission determines to be an endangered species.’ And in this context, ‘taking’ means to ‘hunt, pursue, catch, capture, or kill’ or to ‘attempt’ any of these activities. See Fish & Game Code 2006 California Edition (San Clemente, CA, 2006), pp. 15, 118, and 219. In addition, Codes 2081 and 2081.1 make clear that endangered species’ appearing on one's private property does not exempt one from this prohibition of ‘taking them’. See Fish & Game Code, pp. 118–19.

¹⁵ See ‘Death’ in The Metaphysics of Death, ed. John Martin Fischer (Stanford, 1993), pp. 61–9.

¹⁶ Boonin is an example of someone who argues that an abortion can be permissible but still not necessarily good. As he explains, ‘[I]t follows . . . that the claim that an action is permissible does not justify the conclusion that it should be performed. So even if we conclude that it is morally permissible for a woman to have an abortion, it will not follow that having an abortion is what she ought to do’ (see A Defense, p. 7).

¹⁷ In the first volume of his Concluding Unscientific Postscript (Princeton, 1992), pp. 185–8, Kierkegaard claims to have seen his life mission as that of ‘making difficulties’ wherever he found life to have become ‘too easy’ – e.g., in ‘Christendom’.