Natural Law Theory and Objective Prescriptive and Proscriptive Duties

Some Christian thinkers have suggested that we can, in fact, derive an ought from an is; that we can derive an imperative from an indicative. They argue that Natural Law theory may license this claim. let us understand that what is meant by ‘Natural Law theory’ begins with the Aristotelian assumption that “the good has been well described as that at which everything aims”(NE, 1094a2-3). For instance, Alfredo Watkins explains:

On new natural law theory we immediately perceive certain states of affairs as to be pursued, and from this we determine what we ought to do; the states of affairs to be pursued are instances of the ‘basic goods’, which are immediately recognizable aspects of human flourishing.
~New Natural Law and Deriving an ‘Ought’ from an ‘Is’

I think he’s right in a trivial sense, but the difficulty here is that the prescriptive ‘ought’ isn’t what we mean when we talk about a moral imperative. We don’t just mean a subjective (albeit natural) prescription, but we also mean an objective prescription and an objective proscription. To say that there are objective natural values is trivially easy to say even for the Naturalist, but to say that they entail objective moral duties is quite another matter. For instance, on Naturalism I may value survival, but I have no moral obligation to value survival. Perhaps if the Naturalist argued that we have a moral obligation to the rest of society then they could argue that we have a moral obligation to value our own survival (as our own suicide hurts society at large). However, the Naturalist is going to have to be reduced to saying that we value society and that this is the reason we have a duty to it (prescriptively). In the end the Naturalist can get us only values which together can prescribe a system of ‘oughts’. This would allow somebody to simply spurn the values given by our natural constitution (such as the desire for health and general well-being). This was the same mistake Ayn Rand made.

However, generally the Theist who believes in objective duties will argue that duties do not depend on our values (for then they would be subjective). Rather, we have objective moral duties (where objective means: independent of perception or belief) which are grounded in God. These duties are not only objective, but they are also prescriptive and proscriptive.

Let me put this argument this way:

  1. If the Theist can derive an ‘ought’ from an ‘is’, then the Atheist can derive an ‘ought’ from an ‘is’.
  2. However, the Atheist cannot derive an ‘ought’ from an ‘is’.
  3. Therefore, the Theist cannot derive an ‘ought’ from an ‘is’.

In other words, God’s existence, or the worldview of Theism, can do nothing to license the claim that moral duties can be derived from the way the world is. Further, the reason neither the Theist nor the Atheist can do this is because: one cannot derive an objective duty which is prescriptive and proscriptive from any matter of fact.

  1. We cannot derive an objective duty which is prescriptive and proscriptive from any matter of fact.
  2. However, what the ethicist means by an ‘ought’ is an objective duty which is prescriptive and proscriptive.
  3. Therefore, we cannot derive what the ethicist means by an ‘ought’ from any matter of fact.

If the Analytic Thomist can, then so can the Naturalist, but I maintain against both of them that neither of them can derive an objective proscription from an indicative. I also maintain that when we speak about objective duties what we mean is that there are objective proscriptions as well as prescriptions (that, in addition to there being a ‘right’ way to act, there is also an objectively sinful or ‘wrong’ way to act – independent of our perceptions or beliefs). Thus, I think that Alfredo Watkins is correct to say that we can derive an ought from an is if by it he means a prescriptive ought, but not if he means a proscriptive ought. It is premise (7) of Alfredo’s argument “If A is an aspect of human flourishing, then instances of A are states of affairs that ought to be pursued. [by NNL]” that introduces the imperative, but isn’t, I think, attentive to whether that kind of ‘ought’ is indeed what the ethicist who says “we cannot derive an ought from an is” has in mind.

Finally, I invite everyone to check out Alfredo’s blog, which I discovered a while ago, and have had an itch to respond to or interact with ever since. It can also be found added to my blogroll list at the bottom of the page.


About tylerjourneaux

I am an aspiring Catholic theologian and philosopher, and I have a keen interest in apologetics. I am creating this blog both in order to practice and improve my writing and memory retention as I publish my thoughts, and in order to give evidence of my ability to understand and communicate thoughts on topics pertinent to Theology, Philosophy, philosophical theology, Catholic (Christian) Apologetics, philosophy of religion and textual criticism.
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