Wednesday, January 09, 2013

Ought and Is

In my philosophical folklore post last week I asked about other tidbits of philosophical folklore, and commenter Ray Ingles gave one example:

The “is-ought fallacy” is another recurring ‘folk philosophy’ phrase – meaning “you can’t derive an ‘ought’ from an ‘is’”, after Hume.

This is a very interesting one, and it is undeniably common — even the exact phrase “you can’t derive an ‘ought’ from an ‘is’” returns something like 48000 hits on Google, and when you start adding variations, the number explodes. The principle is sometimes called ‘Hume’s Guillotine’, a label that seems to go back to philosopher Max Black in the 1960s. Others call it ‘Hume’s Law’, the source of which I have not been able to trace, although it does seem to be both more recent and less useful, given that there are plenty of other things that have also been called ‘Hume’s Law’. As is often the case with things that reduce to a slogan, it seems to be used in very different ways. Here are some various formulations that often get thrown around when talking about the ‘Is-ought fallacy’ or ‘Hume’s Guillotine’:

You can’t derive an ‘ought’ from an ‘is’.
You can’t derive an imperative from an indicative.
You can’t derive value judgments from factual judgments.
You can’t derive normative claims from factual claims.
You can’t derive evaluative claims from non-evaluative claims.

But oughts, imperatives, and value judgments are all very different things. ‘Ought’ statements, for instance, are generally indicative statements. What adds to the confusion is that all of these, even if they are often true, seem to have obvious counterexamples, yet they are all treated as absolute statements. There are many intriguing puzzles here, and the question is sometimes even raised as to whether the use of the principle is self-defeating. As a friend of mine, James Chastek, once joked, “We can’t derive an ‘ought’ from an ‘is’; therefore we ought not to try.”

Perhaps we should go back and look at the source of this slogan, David Hume (1711-1776).

Read the rest of this post at the First Thoughts blog.


  1. MrsDarwin8:40 AM

    Your discussion of "taste" in regards to moral judgment helps me make sense of Austen's description of Fanny Price as having a high degree of good taste. In context I could see what Austen was referring to, but the frequent references to Fanny's taste have been jarring to me, especially as both Henry and Mary Crawford are mentioned as having good taste in aesthetic affairs, a usage that's more familiar to modern ears.

    Would you say that "taste" in Fanny's case is used to mean having a highly-developed conscience?

  2. branemrys8:58 AM

    I think there's definitely a link. One of the points that is made by the 'picturesque' passages of MP is that the Crawfords have an aesthetic taste that is artificial, whereas Fanny's aesthetic taste gives the natural world a much larger role:

    "That was the only point of resemblance between her and the lady who sat by her: in everything but a value for Edmund, Miss Crawford was very unlike
    her. She had none of Fanny's delicacy of taste, of mind, of feeling; she
    saw Nature, inanimate Nature, with little observation; her attention was
    all for men and women, her talents for the light and lively. In looking
    back after Edmund, however, when there was any stretch of road behind
    them, or when he gained on them in ascending a considerable hill, they
    were united, and a "there he is" broke at the same moment from them both,
    more than once."

    "Delicacy of taste" was a quasi-technical term in the period. Hume wrote a short essay on it, for instance, and a lot of what he says about it makes a great deal of sense when applied to Fanny.

    I often insist that Mansfield Park is (among other things) great moral philosophy in novel form, and this is one of the reasons why: it can be read as a critical examination of the usual 'moral taste' theories, and the proposal of a more subtle approach to the question of how taste relates to morality. Taken overall, the moral taste theories of Shaftesbury and Hume arguably lead to something like the Crawfords, and Austen does an excellent job both of showing why that result is attractive and also why it is wholly inadequate. I don't know if she had Shaftesbury and Hume specifically in mind, since these 'moral taste' views had considerable influence (she might be thinking of other novels, for instance, rather than specific philosophical versions), but MP is a brilliant critical look at the relation between taste and morality.

  3. MrsDarwin9:43 PM

    I agree that the Crawfords are a fascinating moral paradox: Mary has an almost exquisite sensibility for Fanny's feelings at the beginning of the novel, sheltering her from the abuse of others over the play in an honestly commendable fashion. She's just being "decent", and it's attractive in her. But her moral sense doesn't seem to run any deeper than being decent in drawing rooms.

    So would you say that there's a modern equivalent of the "moral taste" idea?

  4. branemrys7:18 AM

    Good question. The types of things that are discussed has shifted, so any analogues wouldn't be very close. Autonomy, perhaps, or fairness, would be analogous in their importance.


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