Thursday, April 01, 2004

Bridging the IS/OUGHT gap

To pick up from where I left off a couple of posts ago: What does 'ought' mean?
If we assume metaphysical naturalism, then nothing exists outside the world of 'is' (i.e. that which is open to empirical investigation). This implies that either normative concepts (such as 'ought') can be reduced to a purely descriptive form, or else those concepts do not refer to anything real.

Now this poses something of a problem for us, since the phenomenology of our experience suggests to us that normative facts (eg "you should not lie") are of an entirely different nature than descriptive facts (eg "snow is white"). However, Alonzo Fyfe suggested that this is simply because "ought" is a particular subset of "is", with noticable distinctions which set it apart from the typical subsets. Rather like whale is a type of mammal, despite being of an entirely different nature from, say, dogs.

So what type of real-world entity does "ought" refer to? From where does it get its apparent prescriptivity? What makes it different from normal descriptive facts like 'snow is white'? The easiest way to approach these questions is probably to forget about morality for a moment, and just consider "prudential oughts", or hypothetical imperatives.

Consider the following examples:
  • John wants to watch The Simpsons, so what channel should ('ought') he set his TV to?
  • You should leave now if you want to get to the movie on time.
  • I've got a big exam tomorrow, so I really should study.
It should be clear that in each of these cases, the 'ought' (or 'should') is alerting us to what must be done in order to fulfill a particular desire. Sometimes (as in the final example) the desire may be implicit, but it nevertheless is crucial: unless I want to do well in the exam, there is no reason for me to study - it would no longer be true that I "ought" to.

In effect, "If you want Y, then you ought to do X", is just another way of saying "Doing X is such as to fulfill the desires in question" (where the desires in question are 'Y'). They mean the exact same thing (assuming a truth-conditional theory of meaning). Yet the second sentence is purely descriptive - it makes no mention of 'ought', it is purely within the world of 'is'. Thus we have successfully bridged the is/ought gap, at least for prudential 'oughts'.

Now we are in a position to answer where prescriptivity comes from - in a world of 'is', how is 'ought' even possible? The answer is found in human desires. The proposition "You ought to X" has no prescriptive properties in and of itself (the words are purely descriptive, as the translation in the previous paragraph demonstrates). Any prescriptivity is attached to the proposition by us, and the source of the prescriptivity is our desire-set.

The most widely accepted theory of human action is BDI theory, or Belief-Desire psychology. The core of this theory states that people always act so as to fulfill their (present) desires, according to their beliefs (about how to best achieve this). So if we gain a new belief about how to best fulfill our (present) desires, then we will (as a brute fact of human nature) act on that belief. To pre-empt the obvious counterexamples: If I continue to smoke despite knowing that it is bad for my health, that simply shows that my current desire to smoke is stronger than my current desire for future health benefits.

The end of all human action is the fulfillment of our desires. We use the word/concept 'ought' to bring attention to possible courses of action which (it is believed) will help attain that end. Desires are real, actions are real, and the relationship between them (i.e. "ought") is real. It is thus intrinsically descriptive in nature - the prescription gets attached only when human nature is added into the equation. Our desire set is precisely the list of prescriptions which govern our actions.

You might wonder if this makes the notion of 'ought' redundant: after all, if we always act to fulfill our desires anyway, what do we need this extra notion of 'ought' for? But note that we only act according to our current desires, whereas the concept of 'ought' can refer to the fulfilment of any desire (or set of desires). Thus in the above example of the smoker, we can sensibly say that although I might in fact smoke (because it fulfills my present desires), I 'ought' not to (with regard to the fulfilment of my future desires).

So prudential 'oughts' are part of the world of 'is' (the real world), and can be described purely in terms of real-word entities - such as desires and actions. Specifically, I claim that "You (prudentially) ought to do X", is truth-functionally equivalent to "Doing X is such as to fulfill the desires in question".

But what about morality? The moral 'ought' is somewhat different, since it is considered to (somehow) be binding on agents, regardless of their personal desires. The moral objectivist posits a notion of 'ought' which is supposedly independent of desires. Yet according to the above analysis, offering an 'ought' without a corresponding desire set (for the ought to be 'in regard to'), seems to be as incoherent as offering a location without a corresponding reference location (eg "the keys are above the table" makes sense, whereas "the keys are above" does not!).

This problem will be further examined in future posts...

[Update: this post is seriously flawed -- see my more recent posts on 'Empty Definitions' and 'Is Normativity Just Semantics?']


  1. Have you read a book called "After Virtue", by a chap called "MacIntyre"? He makes a similar point to Fyfe (as far as I can tell from your post, and from my memory of the book), except he puts the idea into a very broad historical context - the history of human morals from Homer to Neitszche. His main thesis is that, whereas Aristotelean virtues (which I suppose are just morals) were designed to move people towards a known telos, Enlightenment moral theorists had no notion of ends - of what kind of person morals were designed to produce - and they (Kant, Roussea etc) instead tried to formulate moral laws based on what human nature *is*, rather than what it *should* become. His final conclusions are a bit fluffy and unconvincing (he blathers on about "narrative" and "life-unity" for a while) but it's an interesting read.

    I don't know if his thesis is right or not - I haven't read enough books - but it seemed to make sense with regards to Rousseau. I know nothing about Rousseau except for what you can find in the Discourses on Art and Science and on the Origins of Inequality, but his moral reasoning seems a little suspect, from what little I have gathered: humans are driven by two principles "anterior to reason", including a "natural repugnance to see any sensitive being perish or suffer"; THEREFORE, we have a moral duty to exercise a natural repugnance for such sensitive beings.

    I've probably done the old mud-wrestler an awful injustice there, and you'ld know better than me, but the book's quite good.

  2. I've heard about MacIntyre, but haven't read him myself. (I should also add that my views have changed considerably since writing this post. Cf. my latest Canta column.)

  3. Thank you, Richard, for letting me link to this essay (and the other one). Although the discussion has been low, it has raised several interesting points in regard to your essays, mostly this one.

    If you would like to clarify your essays or join the discussion, click .



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