JENSEN, S., Knowing the Natural Law, The Catholic University of America Press, Washington, 2015, p. 4

p. 4 Grisez attempted to achieve his goal by emphasizing one single truth about Aquinas’s natural law, namely, that the first principles of the natural law are per se nota, that is, they are known immediately from an understanding of the terms, with no need for deductive reasoning. These first principles, which seem to be something like ought-statements, cannot possibly be derived from is-statements. After all, they are not derived from anything else whatsoever. They are own starting points, depending upon nothing prior. Practical reason has its starting points, just as does speculative reason. The one does not depend upon the other.

With this move, teleology has also been swept away. In order to know the truths about morality, we do not need to know anything about the end or purpose of activity. Indeed, we cannot possibly start with speculative truths concerning human beings and their actions and then reach the ought-statements of practical truth. That would be to commit the naturalistic fallacy. That would be to ignore the perse nota character of the first principles of practical reason. These principles are known without knowing anything about teleology. From these first principles, which are themselves ought-statements, we reach other ought-Statements concerning ethics. No fallacy is committed; no teleology is needed.

In the same manner, God is no longer necessary for moral reasoning. We can understand ethical truths without understanding God. The truths are known in themselves, independently of our knowledge of God. We have no need to derive ethics from God’s will.

Grisez’s account included other features that impinge less directly upon our concern. The first principles of the natural law, he claimed, and especially the very first principle of practical reasoning, are premoral, that is, they direct us to pursue various goods but not necessarily in a moral manner.1 The sinner, as well as the virtuous person uses the first principles. The very first principle, for instance, says that we should pursue what is good and avoid what is evil. Even the sinner, however, pursues some good, for instance, the adulterer pursues pleasure as if it were good.

Grisez also claimed that the basic goods of human beings, which correspond with the first precepts of the natural law, are incommensurable, that is, they cannot be measured one against another.2 They are all equally important. We cannot say, for instance, that the good of knowledge is more important than the good of play or that the good of friendship is more important than the good of life. This incommensurability follows, thought Grisez, upon the underived character of the first precepts. If the basic goods were derived from some higher good. Then they could all be compared in relation to this highest good. As it is, each good is independent.

Incommensurability has further implications. No single good serves as the ultimate end of human life; since no good is greater than another, all are equally ends. Our reasoning concerning one good being for the sake of another good, which in turn is for the sake of another good, and so on, must stop at some basic good. All the basic goods, however, are good in and of themselves, without reference to something further. Our reasoning, then, can stop at any of the basic goods and need not work its way back to one single end

Grisez has had his detractors. Figures such as Ralph Mclnerny and Henry Veatch have attacked Grisez’s nonnaturalism, arguing instead for a naturalism or descriptivism grounded in Aquinas.3 No aspects or Grisez’s thought, as expressed above, has gone untouched. Within the Thomistic discussion, the dispute concerning is-statements and ought statements took on a slightly different hue, coming to be phrase in terms of speculative knowledge as opposed to practical knowledge. Grisez claimed that our knowledge of the natural law, which is practical knowledge, has its own practical starting points, with no dependence upon speculative knowledge. Others claimed that practical knowledge always arises from speculative knowledge.

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1 8. Grisez, “First Principle,” 181-86. 

2 Grisez, et al, Practical Principles, Moral Truth, and Ultimate Ends,” American Journal of Jurisprudence 32 (1987): 99-151, at 110. See also Finnis, Natural Law, 92-95; and John Finnis et al “The Basic Principles of Natural Law: A Replay to Ralfph Mclnerny” American Journal of Jurisprudence 26 (1981): 11-31, at 28-31. 

3 10. See, for instance, …