¹ See Feser, Edward, Locke (Oxford: Oneworld Publications, 2007)Google Scholar, for an account of the differences between Scholastic and Lockean conceptions of natural law.

² For a useful account of the differences between the classical and “new” natural law theories, written from a classical point of view, see Oderberg, David S., “The Metaphysical Foundations of Natural Law,” in Zaborowski, H., ed., Natural Law and Contemporary Society (Washington, DC: Catholic University of America Press, 2008)Google Scholar.

³ For example, the libertarian theorist Randy Barnett characterizes his position as grounded in “natural law” because it takes account of general empirical facts or “natural laws” about human biology, psychology, and social organization. See Barnett, Randy, The Structure of Liberty: Justice and the Rule of Law (New York: Oxford University Press, 1998), 4–12Google Scholar. One problem with this characterization is that it makes the “natural law” label vacuous, since surely every moral theorist, including those who explicitly reject natural law theory, would claim to take account of such general empirical facts.

⁴ And there may not be, even then; for the “fact/value distinction,” though still (usually unreflectively) accepted by many contemporary philosophers, has been criticized by philosophers not necessarily sympathetic to classical metaphysics. See, e.g., Putnam, Hilary, The Collapse of the Fact/Value Dichotomy and Other Essays (Cambridge, MA: Harvard University Press, 2004)Google Scholar. Criticisms by writers who are sympathetic to classical metaphysics include Martin, Christopher, “The Fact/Value Distinction,” in Oderberg, David S. and Chappell, Timothy, eds., Human Values: New Essays on Ethics and Natural Law (New York: Palgrave Macmillan, 2004)Google Scholar; and Oderberg, David S., Moral Theory: A Non-Consequentialist Approach (Oxford: Blackwell, 2000), 9–15Google Scholar.

⁵ Foot, Philippa, Natural Goodness (Oxford: Clarendon Press, 2001), chapter 2CrossRefGoogle Scholar. The relevant essay by Thompson, Michael is “The Representation of Life,” in Hursthouse, Rosalind, Lawrence, Gavin, and Quinn, Warren, eds., Virtues and Reasons: Philippa Foot and Moral Theory (Oxford: Clarendon Press, 1995)Google Scholar.

⁶ As Foot notes, questions about the evolutionary origin of a species can largely be set aside here, for the point of an Aristotelian categorical is to describe a species as it actually exists at a point in time, whatever its origins. One might still wonder, however (as Gerald Gaus did in commenting on an earlier version of this essay), whether the existence of such borderline cases as evolutionary transitional forms, which would seem to be indeterminate as to their essence, casts doubt on biological essentialism. But it does not. As David Oderberg points out, characterizing such forms as indeterminate presupposes a contrast with forms which are not indeterminate (such as the evolutionary ancestors and descendants of the forms in question), and thus does not entail that there are no biological essences at all. Furthermore, given the general arguments in favor of classical essentialism, there is no reason to doubt that even such borderline cases do, in fact, have essences of their own, different from the essences of the forms with which we are contrasting them. See Oderberg, David S., Real Essentialism (London: Routledge, 2007), chapter 9CrossRefGoogle Scholar, for a detailed discussion of this issue.

⁷ On one currently popular account of how this might work, to say (for example) that the kidneys existing in such-and-such an organism have the “function” of purifying its blood really amounts to something like this: Those ancestors of this organism who first developed kidneys (as a result of a random genetic mutation) tended to survive in greater numbers than those without kidneys, because their blood got purified; and this caused the gene for kidneys to get passed on to the organism in question and others like it. To say that an organ's function (now) is to do X is therefore shorthand for saying that it was selected for by evolution because its earliest ancestors did X. There are several well-known difficulties with this sort of account, however. For example, it seems to imply that an organ that did not arise through natural selection could not have a function; yet it is surely at least theoretically possible that organs with genuine functions could arise through means other than natural selection. Related to this, the account seems to imply that we cannot know the function of an organ until we know how it evolved; yet it is obvious, even to someone who knows nothing about evolution, what functions eyes, ears, and many other bodily organs serve. For further discussion of this issue, see Feser, Edward, The Last Superstition: A Refutation of the New Atheism (South Bend, IN: St. Augustine's Press, 2008), 248–57Google Scholar.

⁸ Austin, J. L., “Ifs and Cans,” in his Philosophical Papers, 3rd ed. (Oxford: Oxford University Press, 1979), 231CrossRefGoogle Scholar. Austin's topic was the analysis of the verb “can.”

⁹ See Feser, The Last Superstition; and Feser, Edward, Aquinas (Oxford: Oneworld Publications, 2009)Google Scholar.

¹⁰ Aquinas, , Summa Theologiae, translated by the Fathers of the English Dominican Province as The Summa Theologica, 5 vols. (Notre Dame, IN: Christian Classics, 1981), I.22.2Google Scholar.

¹¹ That there is something to what Aquinas is saying here should be obvious to anyone familiar with the history of philosophical debate over causation since David Hume. I would submit that Humean puzzles about efficient causality arose precisely because of the early modern philosophers' decision to abandon final causality. See the works cited in note 9 for elaboration of this suggestion.

¹² Armstrong, D. M., The Mind-Body Problem: An Opinionated Introduction (Boulder, CO: Westview, 1999), 138–40Google Scholar.

¹³ Molnar, George, Powers: A Study in Metaphysics (Oxford: Oxford University Press, 2003)Google Scholar.

¹⁴ See Ellis, Brian, Scientific Essentialism (Cambridge: Cambridge University Press, 2001)Google Scholar; and Ellis, , The Philosophy of Nature: A Guide to the New Essentialism (Chesham: Acumen, 2002)Google Scholar.

¹⁵ It should be noted that Ellis and Cartwright, unlike some of the authors to be cited later, do not extend their neo-Aristotelianism to biology, but confine it to physics. A more thoroughgoing Aristotelianism is defended in Oderberg, Real Essentialism, and in Oderberg, David S., “Teleology: Inorganic and Organic,” in Gonzalez, A. M., ed., Contemporary Perspectives on Natural Law (Aldershot: Ashgate, 2008)Google Scholar.

¹⁶ Cartwright, Nancy, “Aristotelian Natures and the Modern Experimental Method,” in Earman, John, ed., Inference, Explanation, and Other Frustrations: Essays in the Philosophy of Science (Berkeley and Los Angeles: University of California Press, 1992), 70Google Scholar.

¹⁷ Ariew, André, “Teleology,” in Hull, David L. and Ruse, Michael, eds., The Cambridge Companion to the Philosophy of Biology (Cambridge: Cambridge University Press, 2007), 177Google Scholar. For Paley's design argument, see Paley, William, Natural Theology (C. Knight, 1836)Google Scholar.

¹⁸ Turner, J. Scott, The Tinkerer's Accomplice: How Design Emerges from Life Itself (Cambridge, MA: Harvard University Press, 2007)CrossRefGoogle Scholar.

¹⁹ Delbrück, Max, “Aristotle-totle-totle,” in Monod, Jacques and Borek, Ernest, eds., Of Microbes and Life (New York: Columbia University Press, 1971), 55Google Scholar.

²⁰ Davies, Paul, The Fifth Miracle: The Search for the Origin and Meaning of Life (New York: Simon and Schuster, 1999), 122Google Scholar. Peter Godfrey-Smith is one philosopher of biology who resists the idea that genes encode for phenotypic traits, but even he concedes that they encode for the amino acid sequence of protein molecules in a way that involves semantic information. Though he does not draw the lesson, this would seem all by itself to concede the reality of something like Aristotelian teleology. See Godfrey-Smith, Peter, “Information in Biology,” in Hull, and Ruse, , eds., The Cambridge Companion to the Philosophy of BiologyGoogle Scholar.

²¹ Two important recent defenses of this thesis are Schueler, G. F., Reasons and Purposes: Human Rationality and the Teleological Explanation of Action (Oxford: Oxford University Press, 2003)CrossRefGoogle Scholar; and Sehon, Scott, Teleological Realism: Mind, Agency, and Explanation (Cambridge, MA: MIT Press, 2005)Google Scholar.

²² Whitehead, Alfred North, The Function of Reason (Princeton, NJ: Princeton University Press, 1929), 12Google Scholar.

²³ My own view is that an explanation of intentionality in purely materialistic-cum-mechanistic terms is impossible in principle. See Feser, Edward, Philosophy of Mind: A Short Introduction (Oxford: Oneworld Publications, 2005), chapter 7Google Scholar, for a survey and defense of various arguments for this position; see also chapters 5 and 6 of Feser, The Last Superstition.

²⁴ Far from being Aristotelian in spirit, Paley's “design argument” and the “intelligent design” theories that have succeeded it essentially concede the idea that the physical universe is inherently mechanistic or nonteleological. Such arguments are thus as radically different from the theistic arguments of an Aristotelian like Aquinas as modern “natural law” theories are from classical natural law. See the works of mine cited in note 9 for discussion of this issue.

²⁵ Aquinas, Summa Theologiae I-II.94.2.

²⁶ Hence, from a classical natural law point of view, the problematic status of moral obligation in modern moral philosophy is a symptom of the moderns' abandonment of final causes. In general, from a classical point of view, many philosophical problems often characterized as “perennial” or “traditional” (e.g., the mind-body problem, the problem of personal identity, puzzles about causation, and many others) are in fact merely by-products of the moderns' adoption of a mechanistic philosophy of nature, and do not arise, or at least do not arise in so puzzling a form, on a classical metaphysical picture. See Feser, The Last Superstition, chapter 5, for development of this idea.

²⁷ Cronin, Michael, The Science of Ethics, Volume 1: General Ethics (Dublin: M. H. Gill and Son, 1939), 222Google Scholar.

²⁸ Foot, Natural Goodness, 15.

²⁹ As a fully worked out natural law account of the matter would show, this does not entail that every human being is under an obligation to become a parent, but it does entail that if someone does become a parent, he is obligated to be a good one, with everything that that implies.

³⁰ Note, however, that the weaker the obligation is, the weaker is the right generated by it. (Cf. the distinction between perfect rights and imperfect rights discussed below.)

³¹ Fagothey, Austin, Right and Reason, 2nd ed. (St. Louis: The C. V. Mosby Company, 1959), 250Google Scholar. Cf. Oderberg, Moral Theory, 53–63.

³² Explaining exactly how and why this is the case (and what the implications are for the debate over “same-sex marriage”) would require an excursus into the classical natural law approach to sexual morality, which is beyond the scope of this essay. Readers interested in an exposition of this approach are directed to chapter 4 of Feser, The Last Superstition.

³³ For classical natural law theory, this rules out abortion and euthanasia but not capital punishment or just wars. For a useful recent explanation of why this is the case, see Oderberg, David S., Applied Ethics: A Non-Consequentialist Approach (Oxford: Blackwell, 2000)Google Scholar.

³⁴ Bittle, Celestine N., Man and Morals (Milwaukee, WI: Bruce Publishing Company, 1950), 293Google Scholar; emphasis added.

³⁵ Higgins, Thomas J., Man as Man: The Science and Art of Ethics, rev. ed. (Milwaukee, WI: Bruce Publishing Company, 1959), 231Google Scholar.

³⁶ Aquinas, Summa Theologiae I-II.96.2.

³⁷ It causes him many other problems too; for discussion of these problems, see Feser, Locke.

³⁸ Nozick, Robert, Anarchy, State, and Utopia (New York: Basic Books, 1974)Google Scholar. Feser, Edward, On Nozick (Belmont, CA: Wadsworth, 2004), chapter 3Google Scholar, offers a sympathetic discussion, though it was written at a time when I believed (as I no longer do) that Nozick's theory of rights could be grounded in a classical natural law approach to moral theory.

³⁹ See, e.g., Narveson, Jan, The Libertarian Idea (Philadelphia, PA: Temple University Press, 1988)Google Scholar.

⁴⁰ Foot, Natural Goodness, 16; emphasis in the original.

⁴¹ Fagothey, Right and Reason, 243.

⁴² It is sometimes claimed that classical natural law theory supports the moral legitimacy of slavery, but this is highly misleading at best and at worst slanderous. What natural law theorists have held is that, since it is obviously morally unproblematic for one person to come to owe another this or that particular service as a matter of right, it is in principle possible that someone could come legitimately to owe another service for some prolonged period of time, perhaps even a lifetime. For example, such servitude might be imposed as a punishment for a crime. But this is a far cry from chattel slavery, slave hunting, allowing children to be born into slavery, etc., all of which are condemned by natural law theory as intrinsically immoral. (Hence, the African slave trade could not be justified in terms of classical natural law theory.) Moreover, the consensus among recent classical natural law theorists is that even the more limited form of servitude natural law allows in principle is so morally hazardous that in practice it cannot be justified.

⁴³ Indeed, even Locke says that we cannot legitimately commit suicide or sell ourselves into slavery despite our ownership of ourselves, though in his case this is precisely because talk of “self-ownership” is, for Locke, really a kind of shorthand for talk of our leasehold rights over what is ultimately God's property rather than ours.

⁴⁴ A particularly thorough presentation of the classical natural law case for private property can be found in Cronin, Michael, The Science of Ethics, Volume 2: Special Ethics (Dublin: M. H. Gill and Son, 1939), chapter 4Google Scholar, which has informed my discussion here. (In addition, chapters 5–8 contain a lengthy critique of socialism.) Also useful are Bittle, Man and Morals, chapters 16 and 17; Fagothey, Right and Reason, chapters 28 and 29; and Higgins, Man as Man, chapters 17 and 18.

⁴⁵ Classical natural law theorists also typically add that since what is less perfect exists for the sake of what is more perfect, inanimate resources, plants, and animals exist for the sake of man. But the hierarchical conception of reality this presupposes is an aspect of classical metaphysics that I do not have space here to expound or defend. For a general account, see Feser, Aquinas.

⁴⁶ Cronin, Special Ethics, 120. Of course the “little more” (namely, the natural resources out of which a machine is made) is important too. I will have more to say on this presently.

⁴⁷ As Cronin notes, it is irrelevant that some individuals might not in fact have families, for the conclusions of natural law follow from the normal case, from what our nature inclines us to. Thus, insofar as even those who happen not to have children nevertheless have an inherent or natural tendency toward family life, they will retain whatever natural rights flow from this particular aspect of human nature. Ibid., 123–24.

⁴⁸ Cf. Aquinas, Summa Theologiae II-II.66.2. For the arguments of Mises and Hayek, see von Mises, Ludwig, Socialism, 2d ed. (New Haven, CT: Yale University Press, 1951)Google Scholar; and Hayek, F. A., “The Use of Knowledge in Society,” in Hayek, , Individualism and Economic Order (Chicago: University of Chicago Press, 1948)Google Scholar.

⁴⁹ What counts as first occupation? Does an explorer who merely sets foot on the edge of a vast continent thereby come to occupy the whole thing? I would argue that the mark of genuine occupation of a resource is some significant measure of control over it. Cf. my discussion of this issue in “There Is No Such Thing as an Unjust Initial Acquisition,” Social Philosophy and Policy 22, no. 1 (2005): 56–80CrossRefGoogle Scholar.

⁵⁰ Cronin, Special Ethics, 127.

⁵¹ Ibid., 135.

⁵² Ibid., 136. Given the improvements an owner might have made to a resource, or his personal economic stake in it, compensation might be called for in such a case.

⁵³ Mack, Eric, “The Self-Ownership Proviso: A New and Improved Lockean Proviso,” Social Philosophy and Policy 12, no. 1 (1995): 186–218, at 187CrossRefGoogle Scholar. See Feser, “There Is No Such Thing as an Unjust Initial Acquisition,” for a development and defense of Mack's proviso, though I would now qualify much of what I said in that essay in light of the views expressed in this one.

⁵⁴ Note, however, that Cronin indicates that a person could not justly appropriate for himself a previously unowned resource that was known in advance to be necessary for the continued existence of the community. Cronin, Special Ethics, 136.

⁵⁵ Waldron, Jeremy, God, Locke, and Equality (Cambridge: Cambridge University Press, 2002), 159CrossRefGoogle Scholar. Nozick famously gives a similar example in Anarchy, State, and Utopia (p. 175), though without drawing the teleological lesson.

⁵⁶ Again, see Feser, Locke.

⁵⁷ From this and what is said below, it should be clear that I have moved away considerably (though not completely) from the position I defended in Feser, , “Taxation, Forced Labor, and Theft,” The Independent Review 5, no. 2 (2000)Google Scholar.

⁵⁸ Cronin, Special Ethics, 135.

⁵⁹ Hence, the claim that natural resources start out unowned needs to be qualified; everyone has at least this minimal claim over them. But this does not entail anything like initial common ownership of resources, because it does not entail that we all collectively have all the rights constitutive of ownership, such as the right to exclude others from a resource, the right to sell it, the right to transform it, the right to destroy it, and so forth. These rights only come into existence with respect to specific resources once they are acquired via occupation by specific individuals.

⁶⁰ The “transfer” of property via such means—as Nozick famously calls it in order to distinguish buying, inheriting, etc. from what he describes as the “initial acquisition” of previously unowned resources—does not appear to be considered more problematic by classical natural law theorists than it is by Nozick, since once a resource is justly acquired it would seem to follow automatically that an owner, precisely qua owner, can transfer it to others in any way he wishes (in general, anyway; see note 63 below). This is no doubt because, like Nozick, classical natural law theorists are uninterested in preserving any overall pattern of wealth distribution per se, even if they are more inclined than Nozick is to see in this or that particular case of economic distress the possibility of injustice.

⁶¹ I do not mean that owners have no right to refuse to rent or sell to such a person. They may refuse if they see fit. The claim is rather that there is no absolute obligation to refuse to sell or rent to him.

⁶² For a recent defense of the principle of double effect, argued from a classical natural law point of view, see Oderberg, Moral Theory, 86–126.

⁶³ There is also the thorny question of the “just wage,” a concept central to classical natural law thinking about economics and social justice. This is too big a topic to deal with here, but two general points can be made. First, the natural law conception of property rights definitely entails that it is in principle possible for the market wage to diverge from the just wage. To take the most obvious sort of example, someone who legally buys up all the land and businesses in some geographical region, making it impossible for others to support themselves through farming and the like and leaving himself the only possible employer, would be committing an injustice against those whom he employed at mere subsistence wages, even if they “freely” consented to these wages. Second, what this entails in practice is not at all obvious. For real-world conditions are almost never anywhere close to this cartoonish example, and the further they diverge from it, the less clear it is that the market wage really has diverged from the just wage. Thus, while the moral principle that the market wage and the just wage can diverge seems to me obviously correct, it seems equally obvious that by itself this principle tells us very little where practical policy measures are concerned.

⁶⁴ Would the proviso entail that natural resources beyond food, water, etc.—in particular, land, raw materials, and the like—should be redistributed so that as many people as possible might become as self-sufficient as they might have been in the state of nature, as the “distributism” of Hilaire Belloc and G. K. Chesterton would seem to require? No, for at least two reasons. First, if such resources are susceptible of being redistributed as often as doing so would allow yet more people to be self-sufficient, it is hard to see how those holding them could really be said to have private ownership of them. Second, as David Schmidtz has emphasized, appropriation of natural resources is not a zero-sum game. While it diminishes the stock of raw materials that can be “initially acquired” (in Nozick's sense), it increases the stock of wealth that can be owned, and it is the latter which matters with respect to self-sufficiency. Hence, though a starving farmer whose crops have failed and whose cattle have died due to drought may own his land outright, and a middle-class office worker may live his entire life well-fed in a rented apartment, it does not seem plausible to suggest that the former is more self-sufficient than the latter. See Schmidtz, David, “The Institution of Property,” Social Philosophy and Policy 11, no. 2 (1994): 42–62CrossRefGoogle Scholar.

⁶⁵ When Aquinas famously says that the ownership of property ought to be private but its use common (Summa Theologiae II-II.66.2), what he seems to mean is not that those in need of assistance have (in general) a perfect right to my property, but rather that they have an imperfect right to it. For if they had a perfect right to it, it is hard to see in what sense ownership would be truly private. Cf. Cronin, Special Ethics, 134.

⁶⁶ This seems clear at least where questions of economic justice are concerned. On noneconomic questions, most libertarians and socialists are probably equally distant from classical natural law theory. And where charity rather than justice is concerned, I suppose socialists might claim to be closer than libertarians are to classical natural law theory, though in my view it is by no means obvious that socialism is really motivated by charity.