Hume’s is-ought problem and its application to morality

Shane asked:

Could you go over David Hume’s Is-Ought problem and its application to morality?

Answer by Craig Skinner

Hume raises the is-ought issue in a brief passage which I quote selectively:

‘In every system of morality…I have always remark’d, that the author proceeds for some time in the ordinary way of reasoning…., or makes observations concerning human affairs; when of a sudden….instead of is and is not, I meet with no proposition that is not connected with an ought or an ought not. This change is imperceptible; but is…of the last consequence…for what seems…inconceivable, how this new relation can be a deduction from others which are entirely different…’ [A Treatise of Human Nature (Book 3,’Of Morals’), 3.1.1.27 (1740)].

In short Hume points out that facts (what is) can’t logically entail a value judgment (what ought to be). Reasoning from facts to value, a deductive argument from factual premises to judgmental conclusion, is invalid.

Of course an argument to an ought conclusion can be valid if we have an ought premise (with or without factual ones).

An example will illustrate:

P. Torturing animals for fun causes much suffering (a fact, an is statement)
C. We ought not to torture animals for fun (a moral value judgment, an ought statement)

This argument is invalid, exhibiting the is-ought fallacy.

To make it valid we need to add an ought premise (P2) as below:

P1. Torturing animals for fun causes much suffering
P2. Causing much suffering for fun is wrong
C. We ought not to torture animals for fun (it is wrong)

And herein lies the application to morality – what is the justification for the ought premise, in this case the justification for ‘causing much suffering for fun is wrong’.

Different moral theories suggest different justifications:

* feeling (Hume)
* reason (Kant)
* eudaimonia (Aristotle)
* consequences (Mill)
* common agreement (Rawls, Scanlon).
* divine command

To say a little about each:

Hume thinks reason can’t move us to action, only feeling, and that good action is driven by our innate moral intuitions or sentiments. We just feel that torturing for fun is wrong, and this is reinforced when we observe others’ horror and repulsion at the idea.

For Kant, it is wrong because we would thereby treat a fellow rational being as a mere means, not as an end; and torturing for fun is not a maxim a rational being could wish to be universal.

For Aristotle, it is wrong because it damages our soul, it prevents genuine flourishing, it goes against the proper ends or purposes of humans.

For Mill, we should do what makes for the greatest happiness of the greatest number, and this wont include torture for fun (there are subtle issues to be brought out here but now is not the time).

For Rawls and Scanlon, refraining from torture for fun is something all reasonable citizens would agree to, or no reasonable citizen would object to.

On divine command theory, God tells us torturing for fun is wrong (of course this just shows the weakness of the theory, for if we thought, instead, that God did command us to torture for fun, we wouldn’t think it right, we would think God wrong).

Finally, the Is-Ought fallacy is sometimes called Hume’s Law or Hume’s Guillotine, which is fair enough. But It is also sometimes referred to as the Naturalistic Fallacy (because it moves from nature (what is) to values), and this is confusing as that term is also used for attempts to define values in naturalistic terms, something Moore, with his ‘open question’ argument, unfairly accused Mill of doing in Mill’s account of Utilitarianism.

Craig Skinner at PhiloSophos.com