Reply To: Aquinas, Natural Rights and God's Existence


Hello Mark,

The connection between natural law and God is a vexed question. Hugo Grotius, notoriously, claimed that law was either natural or positive, based on reason or on will. Natural law (or natural right) he defined as ‘the Rule and Dictate of right Reason, shewing the Moral Deformity or Moral Necessity there is in any Act, according to its Suitableness or Unsuitableness to a reasonable Nature and consequently that such an Act is either forbid or commanded by GOD, the author of Nature.’ [I, i,10,1] The presence of God in this definition is, technically, otiose, because even if there were no God, the law of nature would still be what it is and would still be binding on all. Grotius makes this point clearly in the Prolegomena: ‘What I have just said would be relevant even if we were to suppose…that there is no God, or that human affairs are of no concern to him…’ The law of nature is as freestanding and as independent of human variability as are the laws of mathematics. Acts judged according to this standard are right or wrong considered in themselves and not because they violate the command of any legislator, either divine or human. This natural law or natural right is incapable of change, so that not even God can change it any more than he can (pace Descartes) make a triangle to have four sides. Grotius writes, ‘the Law of Nature is so unalterable that God himself cannot change it. For tho’ the Power of God be infinite, yet we may say, that there are some Things to which this infinite Power does not extend, because they cannot be expressed by Propositions that contain any Sense, but manifestly imply a Contradiction. For Instance then, as God himself cannot effect, that twice two should not be four; so neither can he, that what is intrinsically Evil should not be Evil.

Although it is clear where Grotius comes down on this question, there is another line of thinking which sees natural law as part of an overarching scheme of laws. The more or less standard account of Aquinas.For Aquinas, Eternal Law is God’s design for the whole of creation. It is ‘the ideal of divine wisdom considered as directing all actions and movements’ and all other forms of law ultimately derive from it. Divine Law is, in effect, what is given to us by revelation in Scripture. Natural Law is ‘the participation of the eternal law in a rational creature,’ a reflection of Eternal Law as we see it manifested in creatures.It gives to each kind of thing ends in accordance with its nature. For man, those ends are the preservation of his own life, life in society, the generation and education of children and the search for truth. Human (or Positive) Law is law as it applies specifically to men in their concrete and practical circumstances. It is an ordinance of reason for the common good made and promulgated by those who have charge of the community.

In the 19th century, Cardinal Newman was to base an argument to God on the existence of conscience, conscience testifying to the existence in us of an awareness of some kind of law.[see Robert Spitzer’s New Proofs for the Existence of God, at

You ask how Rand and Rothbard can accept natural law but deny God? The short answer to you questions is: I don’t know!