Why does Hume believe that ought brings a new relation?

If means-end reasoning, where we can say that one is ought to do X in order to get Y, does not bring a new relation, then in order to tell that ought brings a new relation, we ought to assert that some oughts are not a part of means-end reasoning.

But is there a single example of this? Is there a single example of ought that is not derived from is? If not, how can Hume believe that ought brings a new relation if there is no example?

And I mean not merely omitted means-end reasoning which is a common thing, but a real lack of that reasoning. Neither I mean a manipulation (authors know their own intents), so commonly used in normative theories, that probably Hume mentions when he writes

instead of the usual copulations of propositions, is, and is not, I meet with no proposition that is not connected with an ought, or an ought not.

In fact in this case there is a straightforward explanation why from the position of author we are ought or ought not to do something. Because he simply does not want us to do it (Or is this want itself what Hume means? That all morals are based on wants?). But since such an explanation would probably be distracting it is better to produce a "theory" with no explanation at all. Or produce a better explanation, but it will result in means-end reasoning and would require some introspection.

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    "Why from the position of author we are ought or ought not to do something. Because he simply does not want us to do it" is not how the moralist authors Hume was reading presented their findings. And there isn't a single example of ought being derived from is, your own example simply postulates a "want". But as I told you before, you will find few takers for an ethics based on "wants", so it is a non-starter.
    – Conifold
    Commented Sep 25, 2018 at 0:35
  • @Conifold, well, there are quite many people who believe in morals based on convention. Which is a form of collective wants. And, well, of course they did not present their findings this way - because it would not work this way. And it is not derived from want (it does not follow from my perspective that I ought to do something just because some person wants it) because it is manipulation, that's why.
    – rus9384
    Commented Sep 25, 2018 at 6:26
  • Convention is not a form of collective wants because the latter do not exist, it is a negotiated compromise between individual wants (and other considerations). Even individuals distinguish between what they want and what they ought to do. A philosophical theory has to explain what some people believe and why others don't, including non-subjective aspects of ethics. And not all moralists are insincere and/or manipulative.
    – Conifold
    Commented Sep 25, 2018 at 17:44
  • @Conifold, do you mean that there is no person whose wants coincide with mine? I would argue. Also, we should not forget about cooperation. One person wants to eat, another person wants eat, they cooperate in order to satisfy their wants. When individuals distinguish between wants and oughts, I think clarification is needed. I ought to cook food in order to eat. But probably you mean another oughts. If so, I am not aware of them. I never use oughts in another sense. And I reject the notion of duty. But I'm not sure you are talking about a philosophical theory. Rather, about a psychological.
    – rus9384
    Commented Sep 25, 2018 at 18:03
  • There certainly is no person whose wants coincide with yours, and you'll have to be very vague (as with "eating") to even find similar ones. Your analysis of "ought" is too naive, it does not even cover all of consequentialism, let alone deontology or virtue ethics, and what you personally reject is philosophically moot, in contrast to psychologically. And arguing won't help, you'll be better served by exploring ethics beyond your personal musings.
    – Conifold
    Commented Sep 25, 2018 at 19:42

1 Answer 1


The limits of means/ end reasoning

'Ought' operates in a variety of contexts outside means/ end (instrumental) reasoning.

Take the case of : 'The train ought to arrive by 21.00hrs'. This means that the probability is that it will arrive by that time. This is a probabilistic prediction unconnected with means/ end reasoning.

Again, 'I ought to be at the meeting tonight but I can't make it'. This means or can mean something like (to add context) : 'I had planned to go to the meeting tonight and a lot of people will be expecting me but I can't go because I have cut my arm'. 'Ought' functions non-instrumentally here. It simply contrasts my previous plans and people's current expectations with what I can - or rather, can't - do. The 'ought' may not be a moral 'ought'; it could be merely the 'ought' of etiquette.

What does Hume exactly say ?

I cannot forbear adding to these reasonings an observation, which may, perhaps, be found of some importance. In every system of morality, which I have hitherto met with, I have always remark'd, that the author proceeds for some time in the ordinary way of reasoning, and establishes the being of a God, or makes observations concerning human affairs; when of a sudden I am surpriz'd to find, that instead of the usual copulations of propositions, is, and is not, I meet with no proposition that is not connected with an ought, or an ought not. This change is imper- ceptible; but is, however, of the last consequence. For as this ought, or ought not, expresses some new relation or affirmation, 'tis necessary that it shou'd be observ'd and explain'd; and at the same time that a reason should be given, for what seems altogether inconceivable, how this new relation can be a deduction from others, which are entirely different from it. But as authors do not commonly use this precaution, I shall presume to recommend it to the readers; and am persuaded, that this small attention wou'd subvert all the vulgar systems of morality, and let us see, that the distinction of vice and virtue is not founded merely on the relations of objects, nor is perceiv'd by reason. (Treatise III.1.1..0

To understand why Hume believes that 'ought' introduces a 'new relation' you have to set aside means/ end reasoning and wants. They are, excuse my directness, red herrings.

Hume's sting in tail of Treatise III.1.1. is that no moral 'ought' can ever validly be derived from a non-moral 'is'. Or, said another way, a valid argument cannot have both an ethical conclusion and purely non-ethical premises; the non-ethical premises are ought-irrelevant. Or yet again, nothing about what ought or ought not morally to be the case can be deduced from what (as (i) a pure matter of actual or putative empirical fact or (ii.) a conceptual truth : 'a matter of fact' or a 'relation of ideas' in Hume's language) is or isn't the case. A 'new relation' is introduced when we move from 'is' to 'ought'.

As an example :

  1. The air in New York is high in particulates due to heavy traffic. Therefore
  2. Traffic ought to be banned from New York.

The argument is invalid because there is a logical gap between 'is' and 'ought'. Ethical conclusions ('Traffic ought to be banned from New York') cannot validly be derived solely from non-ethical premises ('The air in New York is high in particulates due to heavy traffic'). Any argument like this, which goes straight from an "is" to an "ought", must therefore be invalid. This is Hume's point.

Hume has his own way of transitioning the gap

Hume does not say, believe or imply that moral 'oughts' are not crucially based on empirical facts or conceptual truths - on what 'is' the case. It is just that he does not believe that the transition is one of logical deduction. Moral judgements - judgements about what we morally ought to do - arise causally from emotion, not logically by deduction.

Hume's position is more clearly stated in the Enquiry concerning the Principles of Morals. There are shifts of viewpoint between the Treatise and the Enquiry, so these are not exactly interchangeable texts, but there is enough linkage for our purposes.

Take an issue, whether euthanasia should be legalised under certain conditions, c1 ... cn. This is not something Hume considers but his ethics can deal with it - how satisfactorily is another matter.

Moral judgement has the following genesis.

  1. We must check all the relevant facts, or as many as it is practicable to check:

... it is often necessary, we find, that much reasoning should precede, that nice distinctions be made, just conclusions drawn, distant comparisons formed, complicated relations examined, and general facts fixed and ascertained.

  1. We must take a general view:

He must here, therefore, depart from his private and particular situation, and must choose a point of view, common to him with others ...


This means that the requisite moral sentiments will arise only if we detach ourselves from our personal interests and inclinations. Adam Smith captured this perspective of 'a point of view, common to him with others' in his idea of the 'impartial spectator' (Theory of Moral Sentiments, I.i.5.4). Hume talked of 'the principle of humanity': http://www.gutenberg.org/files/4320/4320-h/4320-h.htm.

When these conditions are fulfilled, what causally arises is an emotional reaction, which is all that a moral judgement actually is. We experience 'certain peculiar sentiments of pain and pleasure' as Hume puts it in the Treatise:


These sentiments are 'peculiar', sui generis, unique, unlike any other sentiments or emotions in their specific character. To stress the emotional nature of moral judgement Hume observes that 'Morality ... is more properly felt than judged of':



There is much to probe in Hume's statements about moral judgement and its relation to emotion. I am not concerned to analyse or defend those statements here. The point is that when we note Hume's logical objection to the derivation of 'ought' from 'is' and his causal account of the emotional origin of moral judgement, we have left means/ end reasoning and wants far behind.

Logical endnote

It is in fact possible logically to deduce a moral 'ought' from a non-moral 'is'. This can be done as A.N. Prior showed by or-introduction :

'Coffee-drinking is common in the United States; therefore either coffee-drinking is common in the United States or you ought to lend me $100.'

For an assessment of Prior-style manoeuvres, see Campbell Brown, 'Minding the Is-Ought Gap', Journal of Philosophical Logic, Vol. 43, No. 1 (February 2014), pp. 53-69.


Campbell Brown, 'Minding the Is-Ought Gap', Journal of Philosophical Logic, Vol. 43, No. 1 (February 2014), pp. 53-69.

J. Harrison, Hume's Moral Epistemology', Published by Oxford University Press (1976) ISBN 10: 0198750374 ISBN 13: 9780198750376.

Geoffrey Thomas, An Introduction to Ethics, Published by Gerald Duckworth and Co Ltd (1997), Pp.53-8. ISBN 10: 0715624318 ISBN 13: 9780715624319.

  • So, when I believe ethics and reason are incompatible, apparently I'm right. Whatever I believe to be good or right is either what I directly like (aesthetics) or something that will help me get what I like (reason). And hence I consider myself amoral.
    – rus9384
    Commented Mar 16, 2019 at 23:21

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