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Australian philosopher, literary critic, and professional writer. Author of FREEDOM OF RELIGION AND THE SECULAR STATE and HUMANITY ENHANCED.

Friday, January 23, 2009

Deriving "ought" from "is"

I often see it claimed that you can't derive an "ought" from an "is", and I have some sympathy for that view, which is often referred to as "Hume's Law". But I'm reminded by a discussion on Facebook, where I just chipped in, that Hume's point was more subtle.

His complaint seems to be that many philosophers go along piling up "is" statements; then you notice that somewhere along the way they've slipped into "ought" language. But how is that possible? As we'd put it in modern lingo, it seems that no number of statements using the copula "is" can ever (just as a matter of propositional logic) entail a statement with the copula "ought". So it appears that, if these philosophers have arguments that are valid (just as a matter of propositional logic), then they must be relying somewhere on one or more unstated premises that contain "ought". But, I take it Hume is suggesting, such premises are likely to be controversial. Accordingly, we shouldn't be persuaded by the arguments of these other philosophers.

But I think it can be taken a bit further when the famous passage in Hume's Treatise of Human Nature is read in the context of the entire meta-ethical discussion that precedes it. It appears that Hume believes you can derive an "ought" from an "is" in some cases. You can't do it as a matter of propositional logic, but if you understand the meaning of "ought" you can do it as a matter of semantics.

Compare the following:

Premise: Foo is a bachelor.
Conclusion: Foo is male and is not married.

Given the meaning of the word "bachelor", this deduction is perfectly valid. It's a matter of semantics - of meanings - not a matter of using the rules of propositional logic, such as modus ponens, modus tollens, etc.

Hume seems to have a similar idea about how we ground "ought" statements. For Hume, the meaning of "ought" is such that the following (or something like it) is a valid argument:

Premise 1.: Professor Snark has a desire for chocolate.
Premise 2.: Professor Snark believes (or should it be "correctly believes"?) that there is chocolate in the cupboard.
Conclusion: Professor Snark has a reason to go to the cupboard to find the chocolate.
Further conclusion: All other things being equal, Professor Snark ought to go to the cupboard to find the chocolate.

I.e., for Hume to say that somebody "ought" to do something is just to say that they have a reason to do it, or perhaps a reason that actually prevails over any contrary reasons that they might also have.

And we can then look at various kinds of "oughts". Perhaps, for Hume, a moral ought is a reason that is based not just on any old desire but a desire for the welfare or the non-suffering of others, a kind of sympathy for others' pain. Thus, Hume would probably accept something like this as a valid argument.

Premise 1.: Jill Bloggs sympathises with the suffering of Joe Sixpack.
Premise 2.: If Jill Bloggs stops the torturer stretching Joe Sixpack on the rack, Joe Sixpack's suffering will be relieved.
Conclusion: Jill Bloggs has a (moral) reason to stop the torturer stretching Joe Sixpack on the rack.
Further conclusion: Jill Bloggs (morally) ought to stop the torturer stretching Joe Sixpack on the rack.

Obviously, things get a bit more complicated than this. What if Jill doesn't feel any sympathy Joe? We might still want to say that she ought to do what she can to prevent his torture. I think that Hume, at least in his later work, realised that it gets a bit messy, and that the above analysis might be too simple. But he'd still insist that somewhere along the line the various kinds of "oughts" that we recognise will always involve something like a desire and that moral "oughts" will always involve something like sympathy (or desire for another being's non-suffering).

This is all putting the point in modern language, and of course I don't know exactly how Hume would phrase things if he had absorbed modern ways of discussing such issues, but I'm confident that he'd consider the above to be at least a reasonable first approximation of his position. His real point is not to say that "ought" claims are totally ungrounded, but to say that we need to understand the character of "ought" claims and to see how they can't be grounded in just any old "is" ... but must be grounded in certain contingent features of human psychology such as desire and sympathy. He'd insist that morality could never motivate us unless it were grounded in desires (in a broad sense) as well as reason.

Although the theory says that oughts can be grounded, and are not just mysterious, it's importantly a subjectivist theory. Hume doesn't think "ought" claims are altogether ungrounded, but he thinks that they are grounded in the desires and so on that people actually have, so some reference will need to be made to those people and their psychological characteristics. There are no objective "ought" statements in the sense of "ought" statements that are true, totally independently of the psychological characteristics that various human subjects actually have. On the other hand, he thought we were sufficiently similar psychologically to be able to reach agreement on what people (morally) ought to do in various situations. He'd have loved the modern idea that there is an evolved human psychology that underpins our responsiveness to other human beings and our sympathy towards any creature that we can imagine suffering pain.

I happen to think that the views that I've attributed to Hume are more or less correct, but that's not such much my point. My point is more to emphasise that Hume was saying something much richer - more subtle and complex - than just the fact that you can't, as a matter of propositional logic, deduce an "ought" statement from an "is" statement.

But, of course, he realised that too.

7 comments:

David said...

Hi,
This sounds a lot like Searle's argument for the same: http://books.google.com/books?id=kwFc_S3T5BcC&pg=PA38&lpg=PA38&dq=searle+ought+is&source=bl&ots=hQPIFCSyZp&sig=R1pt3W8r42oVVDGSmGgKkEGlUJg&hl=en&sa=X&oi=book_result&resnum=4&ct=result#PPA40,M1

I don't find it terribly convincing, though. It seems to just make the leap from fact to value sound minor by using words equivocally.

Conclusion: Professor Snark has a reason to go to the cupboard to find the chocolate.
Further conclusion: All other things being equal, Professor Snark ought to go to the cupboard to find the chocolate.


If by 'has a reason' in the first line you mean he ought to, then it's question-begging (or at least, the explanation for how you got there is still missing); but if you mean just that his interests will lead him to be motivated to go to the cupboard, then what is the connection to the next line's 'ought'? It seems to just be equivocation between a hypothetical imperative and a categorical imperative.

The same goes for the Jill and Joe example (when you say a 'moral reason', do you mean 'a reason motivated by beliefs-to-do-with-good-and-bad', or 'a reason that one morally ought to accept'?), and the argument seems particularly weak here: "What if Jill doesn't feel any sympathy Joe? We might still want to say that she ought to do what she can to prevent his torture." We might, but why?

If you are, in fact, claiming that 'a reason motivated by beliefs-to-do-with-good-and-bad' and 'a reason that one morally ought to accept' are in fact the same thing, as your mention of psychology suggests, then you've brushed over the glaring objection at hand -- that there's no way such a method of is-ought deduction could get us to anything close to the kind of moral system we'd like to establish (because it would validate both 'good' beliefs-to-do-with-good-and-bad and 'bad' ones equally).

Russell Blackford said...

Hi, David! Thanks for that comment. Guess the Searle book is another thing I need to read. *sigh*

Hume wouldn't think he was using words equivocally. He'd say that "ought" just means having a reason, and having reasons is about a certain fit between your desires and your beliefs about the state of the world out there (or possibly a fit between your desires and the actual state of the world). It seems to me that there's lots of room to make distinctions here, but that the essential insight is correct. In the real world, which contains no spooky moral properties, etc., there's nothing else that "ought" can mean, though because of our upbringings or whatever we have this illusion of some kind of absolute moral law that we're bound by.

On the categorical imperative thing, Hume didn't believe there was such a thing as a categorical imperative, so he couldn't equivocate. He's not trying to explain what a categorical imperative is; he's trying to explain how, in his view, all oughts are ultimately hypothetical imperatives - or at least involve hypothetical imperatives.

I agree with him on that; I don't believe that there are any categorical imperatives, either.

Or rather, there are what's sometimes known as "weak categorical imperatives" as when a social norm tells you to do something ... but there's a sense in which it's really up to you, ultimately, whether you have reasons to accept the authority of the relevant body of social norms. I don't think Hume would have denied that categorical imperatives of that kind exist. But he would have agreed with me that there are no strong categorical imperatives of the kind that Kant later tried to describe.

Kant never succeeded in demonstrating that any such thing exists, and I actually think that he took philosophy in a bad direction with that one. We're still struggling with this hundreds of years later, when Hume was basically right (IMHO).

Not sure I understand your last para. I think you are probably making assumptions that Hume would not make, and I wouldn't either, when you say that the various examples are weak. To me they seem strong, if overly simple. They are too simple, because they ignore the existence of social norms and so don't deal with the full complexity of the real world. Hume tries to tease out some of that in his later work.

There are social norms of various kinds (norms of law, positive morality, etiquette, etc.), and sometimes "ought" really just means, if we interpret it charitably, "this is what the social norm demands". But how did the social norm get there in the first place? Well, presumably because a certain body of rules achieves certain purposes such as social survival and harmony, reduction of suffering, etc. If we agree with those goals, we have a reason (!) to support the social rules and take our direction from them. In fact, most people accept the social rules mindlessly because they have been ingrained by the teachings of parents, etc., but it's alway possible to stand back and ask whether you really do accept them. Hume thought that if you asked that question about the most important social rules - rules about what sort of behaviour is to be admired and considered virtuous ... or the opposite - we'd generally have no problem with accepting them. He did think that we all have a common nature, so he thought that we'd all pretty much agree if we were similarly informed.

I think he was right about most of this. There may well be more slippage than he imagined, i.e. our natures may be more constructed by our different social experiences than he thought. Also, there are outliers, such as psychopaths, who can learn the rules intellectually but don't have reasons (in Hume's sense) to accept them (because they don't have sympathies for others or whatever other kinds of desires might be the "moral" ones). But I'm sure Hume could acknowledge all this - none of it really undermines his theory; it just predicts that if his theory is correct then there will be a mixture of moral agreement and disgreement in the world (with agreement on some central things) and a mixture of people who care about morality and a smaller group of people who don't. On this account, psychopaths are not making any intellectual mistake, but are bad to have around because they put no value on things that are important to the rest of us, such as non-suffering.

But of course what we see is just what the theory, plus some empirical claims from the social sciences, would predict. So the Humean theory is consistent with the empirical evidence.

Of course, I'd develop it in a slightly different way from Hume, given that we know a lot of empirical stuff that he didn't. The original post wasn't so much to say "Hume was right!" as just to point out that what Hume was saying was a lot more subtle than "you can't go from is to ought", which is all most people seem to remember.

Anyway, I may be misunderstanding your objection. If you'd like to rephrase it in the light of the above attempt at an explanaton, this could be a valuable discussion.

Brian said...

Premise: Foo is a bachelor.
Conclusion: Foo is male and is not married.

Given the meaning of the word "bachelor", this deduction is perfectly valid


Didn't Quine think the concept of analyticity was too wishy washy and that saying it rested on definition was no better? I think that was what he was getting at in Two dogmas of Empiricism anyway.

As for Hume, what a legend. I read a lot of books where they blithly dismiss his thinking as some one dimensional simplistic stuff. It seems that if you don't look closely enough and think enough he seems quite light on....Perhaps that's because he could write beautifully, unlike say Kant?

Russell Blackford said...

Hume's thought is very penetrating, though so radical that a lot of philosophy since has taken the form of resistance to it.

I think that a lot of the resistance has been misplaced. E.g., the moral theory needs a lot of detailed work, but the insight that our morality ultimately depends on contingent aspects of human nature should not have been resisted. Hume got this right, IMO, but it still scares people ... partly because we know that human nature is not totally universal: even among "normal" people, some have stronger sympathies than others, and there are those pesky psychopaths around who (as a result of whatever neural abnormalities) just don't have the same kinds of sympathetic responses as the rest of us. It's scary to think, as a good Humean must, that the psychopath makes no intellectual mistake. It means that there's a sense in which morality is not objective, and most people want to resist that conclusion. I think that we should accept it, and I don't believe that it has the horrendous consequences that are often feared.

It does make moral discussion inevitably complicated - i.e., it explains why moral discussion is always going to be messy, and is not just a mess that we can clear up with a simple theory that's independent of all the complications of being human.

But that just makes life hard for philosophers, which is probably a good thing. ;) It doesn't stop everyday moral discourse going on as before, or mean that people will suddenly be less kind to each other.

No offence to you, Brian, but I was kinda hoping David might have posted something in defence of Kant. I was girding myself for a detailed discussion of the lying promise example, which I think Kant misinterprets. But maybe I've misjudged where David is coming from.

David said...

Hi Russell,
Thanks for the thorough reply! And sorry for dropping the ball on getting back to you. I think we largely agree on the facts of the matter (and I wouldn't expect me to come out in defense of Kant if I were you, haha).

I may have misunderstood you initially by assuming that when you talked about 'oughts' you were talking about categorical imperatives — specifically that you were trying to sneak in categorical imperatives where we only really have license to hypotheticals, which many people have attempted to do.

I think part of the reason for their determination, though, is that hypotheticals (which essentially just boil down to statements of fact) really aren't capable of establishing the kind of framework of obligation that we'd like to have, and which we constantly invoke in discussions of morality. The only grounds we're left with on which to criticize someone who, say, prefers the destruction of the world to scratching his finger, are grounds of consistency with his other professed desires.

But psychopathic world-obliterators are not the only area where this leaves us without recourse. Our everyday moral structure depends constantly on Kant-like appeals to individual action, e.g. the call for everyone to take responsibility, 'be Green', vote, not litter, etc. Without the compulsion of categorical norms that have nothing to do with consequences or desires (my 'being Green' or not will have a negligible impact on my environment), no individual has a reason not to freeload on everyone else's prosocial behaviour.

I've often seen people argue that there's no problem for a merely hypothetical-imperative-based morality because "We're all invested in a good society/environment/etc.", so our desires naturally cohere, but this ignores that the causal connection between that desire and one's own actions is essentially nil.

Which is why I feel that these considerations make discussions of morality not merely "more complicated" or fuzzy about the edges, but deeply without the sorts of justification that are needed to get it off the ground. If everyone realized that no principled objection could be made to their being utterly self-interested, we would be in some trouble.

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