Thursday, January 10, 2013

New Natural Law and Deriving an 'Ought' from an 'Is'

Many people have said that we cannot derive an 'ought' statement from an 'is' statement. In one sense this is trivially true, in another it is straightforwardly a mistake in logic. I'll discuss this in relation to new natural law theory and the grounding of morality in metaphysics.

First the sense in which it is true. Obviously if the premises of your argument contain no 'ought' statements then you can't logically derive an 'ought' from them. At best you can conclude from the premises that some ought statement is plausible. However, I think most people who want to say we can derive an ought from an is would all agree with this rather trivial observation.

Now some discussion of natural law: 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. Now, new natural law theorists say we cannot derive an ought from an is. However, they also say that new natural law theory does not carry any commitments one way or the other as to what, metaphysically speaking, human flourishing consists in or is grounded in. After all, everyone can know the natural law in their hearts, and you do not need to be a metaphysician to gain insight into what's right and wrong. But by the same token on new natural law theory, it should be consistent with the theory to say the human flourishing is grounded or consists in something like, say, the perfection of the human form. New natural law should not rule this out.

What follows from this? Well, if this type of theory is possible on new natural law, then supposing it is true, every aspect of human flourishing will at the very least coincide with some aspect of the perfection of the human form. The details of this perfection aren't that important, since the main point of this post is supposed to be logical. So just take some arbitrary aspect of human flourishing A and some arbitrary aspect of the perfection of the human form P. A and P coincide just means that if one exists then so does the other. Now we can launch an argument:

(1) If P and A coincide then P is an aspect of the perfection of the human form if and only if A is an aspect of human flourishing. [by def.]
(2) P and A coincide [prem]
It follows logically that
(3) P is an aspect of the perfection of the human form if and only if A is an aspect of human flourishing. [from 1 and 2]
From this we can infer by the rules of logic that
(4) If P is an aspect of the perfection of the human form, then A is an aspect of human flourishing. [from 3]
(5) P is an aspect of the perfection of the human form. [prem]
Again by the rules of logic:
(6) Therefore, A is an aspect of human flourishing. [from 4 and 5]
(7) If A is an aspect of human flourishing, then instances of A are states of affairs that ought to be pursued. [by NNL]
(8) Therefore, instances of A are states of affairs that ought to be pursued. [by 6 and 7]

(1) just follows from the definition of 'coincide'. (7) is just what new natural law says. Given the premises the rest follows by the incontestable rules of logic. Now, one might question premise (2) and (5). However, it is at least possible for them to be true given new natural law theory. And if they are true then this argument shows one can derive an ought from an is.

Basically, to say we can derive some statement Q from some set S of premises {P1, P2, ... , Pn} just means that there is a proof of Q from S. This is Logic 101 stuff. Given all the premises and definition in our argument we can derive an ought, namely (8). Our premises, (2) and (5) are paradigm 'is' statements. This is why it is false to say we cannot derive an 'ought' from an 'is' statement.

Here's the upshot for natural law theory: If NNL is true, then it is possible for (2) and (5) to be true. If (2) and (5) are true there's a perfectly good sense in which we can derive an 'ought' statement from a set of 'is' statements. Hence, even if NNL is true, it is possible to derive an 'ought' from an 'is' in the precise logical sense of 'derive' above. The only other possibility is to either say aspects of human flourishing can't coincide with anything, which basically means NNL is inconsistent with certain metaphysical theories of flourishing (viz. all of them), or else we are using some other sense of 'derived' in saying an 'ought' can never be derived from an 'is'. As a person sympathetic to NNL myself I think we should go with the latter (or possibly drop the use of the phrase altogether).

4 comments:

Kiel said...

I'm no expert but I'll put down some thoughts. You say:

new natural law theory does not carry any commitments one way or the other as to what, metaphysically speaking, human flourishing consists in or is grounded in. After all, everyone can know the natural law in their hearts, and you do not need to be a metaphysician to gain insight into what's right and wrong.

and you say:
every aspect of human flourishing will at the very least coincide with some aspect of the perfection of the human form

This strikes me as contradictory because both statements are metaphysical and therefore makes one a metaphysician to some extent.

Furthermore, it seems the coincidence (or perhaps correlation) of P and A is a weak ground for objective judgements of right and wrong. It suggests to me that if you ditch a formal metaphysical foundation then you are vulnerable to subjectivity with respect to both variables and ultimately no justification for why the ought should be derived from the is.

ozero91 said...

This is off-topic, but I wonder if the argument can be made: "It is not possible to establish an objective moral standard without final causality." I'm not an expert, so I can't even begin to formulate it, but it would be interesting to know if it were possible. The idea is that naturalists reject God/Divine Commands, and (from my experience) reject telos or final causality in nature, so it would create a dilemma for them.

awatkins69 said...

Hi Kiel,

Sorry for taking forever to respond!

I don't see how the first quotation contains any metaphysical statements. The first is just a statement about what is and is not entailed by new natural law theory, the second is a statement of moral epistemology.

The second quotation on the other hand is a somewhat metaphysical statement, though not that informative.

Now, I'm not saying that the only relation between the perfection of the human form and the dictates of morality is one of coincidence! I am only showing how on this *very modest assumption*, which NNL must concede is possible, on any textbook definition of 'derive' we can be said to derive an 'ought' from an 'is'. Many (all?) contemporary NNLers deny that this is possible.

Now, I *do* think that morality is in a stronger sense grounded in the perfection of the human form, but even if NNLers don't grant this is possible they must at least grant that the perfection and the moral truths coincide so to speak. That is all I need for my argument.

awatkins69 said...

@Ozero91: Some people think you cannot have morality without final causality. Presumably many virtue ethicists think this (cf. Hursthouse, Philippa Foot, et al.) They are naturalists in the sense that they don't believe in any God. Regarding how God fits into the picture, I think that even if God did not exist things would still have their natures, so you don't have to believe in God to have final causality. However, there is still a general correspondence between lack of belief in God and lack of belief in final causality, probably because most people who lack a belief in God for one reason or another are also Cartesian-style physicalists.

As someone sympathetic to a modified New Natural Law view, I am not so sure whether morality is separable from final causality. I suppose in some sense it is so separable, since NNL is not committed to any particular view about what morality is grounded in.