Natural law: Between objectivism and subjectivism

Aristotelian natural law approaches provide an attractive middle road between objectivist and subjectivist answers to various normative questions: the answers to the questions are relative to the kind of entity that they concern, but not to the particular particular entity.

For instance, a natural law approach to aesthetics would not make the claim that there is one objective beauty for humans, klingons, vulcans and angels. But it would make the absolutist claim that there is one beauty for Alice, Bob, Carl and Davita, as long as they are all humans. The natural lawyer aestheticist could take a subjectivist’s accounts of beauty in terms, of say, disinterested pleasure, but give it a species relative normative twist: the beautiful to members of kind K (say, humans or klingons) is what should give members of kind K disinterested pleasure. The human who fails to find that pleasure in a Monet painting suffers from a defect, but a klingon might suffer from a defect if she found pleasure in the Monet.

Are the priors of subjective Bayesianism subjective?

Visual and auditory perception are not subject to rational evaluation. Nobody perceives visually or auditorily in a rational or irrational way. Nonetheless, perception is subject to evaluation. One’s perceptual faculties could function superlatively, adequately or inadequately. The mere fact that they are not subject to rational evaluation does not imply subjectivism about their functioning.

But now consider a Bayesian view on which:

1. Our priors are not subject to rational evaluation.

That view is known in the literature as “subjective Bayesianism”. But if we take seriously the lesson from perception, we should be sceptical of the inference from (1) to:

2. Our priors are merely subjective.

I have to confess to not taking this point seriously in the past, having been misled by the phrase “subjective Bayesianism” and by things I heard from subjective Bayesians.

What might a theory look like on which our priors are subject to evaluation but not rational evaluation? We could take our priors to be a kind of “probabilistic perception” of patterns in the world, a perception that is genetically and/or socially mediated. Such perceptions can be better or worse, just as the person who is looking at a horse and their visual system classifies it as 95% likely to be cat and 5% likely to be a horse is doing less well perceptually than one whose system makes the opposite classification. For instance, someone who has a prior close to 1 for the law of gravitation being an inverse 3.00001th power law is doing less well than someone who has a moderately high prior for it it being an inverse cube law and a moderately high prior for it being an inverse square law.

But if we take the perception analogy seriously, we get this question: What are we “perceiving” with our priors? Maybe something like facts about the sorts of laws worlds like ours have?

Beauty, observation and objectivity

The following fact is typically seen as evidence for the subjectivity of beauty:

1. Very long necks look beautiful to the Padaung but not to contemporary Americans.

But the following fact is not typically seen as evidence for the subjectivity of beauty:

2. Van Gogh's Wild Roses is looks very beautiful by visible light but not so much by x-ray.

Why do we not see (2) as evidence for subjectivity about beauty? I think the answer is simple: Wild Roses is no more meant to be viewed by x-ray light than the Moonlight Sonata is meant to be viewed visually in Fourier transform. Wild Roses and the Moonlight Sonata are intended to be beautiful in those respects that are perceived visually or aurally, respectively, and they succeed admirably at these aims.

We can be a bit more subtle here. A microscopic examination of Wild Roses is not going to reveal the relevant beauty of the work, nor will an auditory examination of the individual notes of the Moonlight Sonata. These works are beautiful in respect of those features that are salient to the appropriately trained "eye" or "ear"—and of course it is not the literal eye or ear that is mainly being trained.

But why not say the same thing about long neck of the Padaung woman, then? She intends her long neck to be beautiful in those respects that are salient to trained Padaung observers. Maybe she is beautiful in respect of her long neck in contemporary North America, too, but we lack the training to make salient to us the features that make her beautiful.

Moreover, it is important to note that the features that make something beautiful may very well be relational features. A part of what can make a work beautiful is precisely the allusions to other works and to the outside world—what makes Anna Karenina a great work of art is in part that the people in it are like real people (which does not mean that every work of literature needs to have people in it that are like real people). Thus it may be that the Padaung woman's long neck is beautiful in part precisely by its relation to particular social practices (and hence when she travels to North America, and is no longer appropriately related to these social practices, she ceases to be beautiful in respect of her neck). Recognizing the aesthetic role of such relations is not a form of subjectivism, relativism or contextualism—it is no more that than recognizing the aesthetic role of the reality of the characters in Anna Karenina makes one a subjectivist, relativist or contextualist.

(Of course, there is also the possibility that the Padaung are simply wrong in their aesthetic judgment. But it is hard to say that without their training. And the possibility of their being wrong is significant evidence for objectivism about beauty.)

[Edited on March 16, 2011, to remove near-contradiction. -ARP]