I enrolled in a class, The Philosophy of Human Rights. The authors of the course readings never use 'duty' and 'obligation' interchangeably, so I suspect that the terms may have distinct meanings.


Do the terms 'duty' and 'obligation' represent different concepts to philosophers? If so, what do the terms mean?

My attempt to answer the question

I thought that a duty might be an obligation that entails action, and that an obligation is a more general term that may or may not entail action.

However, one author, Henry Shue, mentions a 'negative duty', such as a duty to respect a person's right to liberty: In essence, a duty to do nothing to someone. I don't consider actions to include 'doing nothing' (that's 'inaction'), so I don't believe that my definition of 'duty', as 'an obligation that entails action', is correct.

What's the difference between 'duty' and 'obligation'?

Thank you.

  • I wouldn't call obligation a generalization of duty (with the implication that duties are a subset of obligations. Exercising your write to vote is a civic duty, but voting is not obligatory.
    – David H
    Sep 30, 2013 at 17:49

3 Answers 3


It would be interesting to have some passages to compare from these authors that you speak about. I too would say, intuitively, that they can't mean exactly the same. So I put my head into some books (not really) to see what I can come up with. I do not find my finding interesting enough to earn a bounty, but nonetheless I prefer to share.

What I did find interesting was this distinction by Cicero from the Wiki on "duty":

Cicero, an early philosopher who discusses duty in his work “On Duty", suggests that duties can come from four different sources:[2]

as result of being human
as a result of one's particular place in life (one's family, one's country, one's job)
as a result of one's character
as a result of one's own moral expectations for oneself

It also states:

Various derivative uses of the word have sprung from the root idea of obligation, a concept involved in the notion of duty; thus it is used in the services performed by a minister of a church, by a soldier, or by any employee or servant.

The concepts thus seem to be interwoven. The Wiktionary on obligation and duty provided me with information on the etymology of the words.

Obligation: From Latin obligatio, from obligatum (past participle of obligare), from ob- to + ligare to bind, from Proto-Indo-European *leig- (“to bind”).

Duty: From Middle English duete, from Old French deu (“due”), past participle of devoir (“to owe”), from Latin debere (“to owe”), from de (“from”) + habere (“to have”).

But what's really interesting is this Pdf on legal terminology I found. It states that even from a legal point of view, there is uncertainty about the use of these terms. I quote:

The terms ‘obligation’ and ‘duty’ are sometimes used as synonyms. They refer either to the entire contractual relationship between the parties or, more narrowly, to what is due by the obligor to the obligee.

Under American law and English law, as under French law, an informal consensus would appear to have emerged, to the effect that the terms ‘duty’ and ‘obligation’ are synonymous.

For instance, the term ‘obligation’ in the singular or ‘obligations’ in the plural is univocal when it refers to what one party has agreed to perform under the terms of an agreement. In this sense, the positive counterpart of the obligation is the right (‘rights and obligations’), that is to say what the creditor is entitled to receive from the debtor. This is a classical view of the term ‘obligation’ seen as ‘a tie which exists between at least two individual persons which enables one person to request something from the other’1. The obligation should therefore be perceived as including a legal tie, a legal tie between at least two persons and a coercitive power enabling the enforcement of the obligation.

The area covered by duties is wider than that covered by obligations. A duty may be owed to a person other than the other party to the contract. This distinction is in fact applied in English law, in order to define the duty of confidentiality.

It would be useless to quote the whole paper, though I really think that it might answer your question. That leaves me to say that, though it might have seemed to you that they're not used synonymously, both the encyclopedia and the legal praxis claim they pretty much are. As you already figured out, your first thought, namely that "duty" might entail an action, is not right, because of the negative duties. Both concepts can refer to the human as human or to specific qualities. Both have, even etymologically, a reference to the object of the duty/obligation. No difference, even there. There might be a little legal difference, for it seems you can have duties that aren't part of the contract's obligations, but that should have no impact on philosophical jargon, I reckon.

  • @Hal Well, if that's the case you could vote it up (:
    – iphigenie
    Oct 9, 2013 at 8:37
  • latin derivative, answer - would love it without the noise (bounty or not)
    – user4500
    Jun 23, 2014 at 22:00

The idea that there is one fixed concept of either duty or obligation is probably in doubt, but there could probably be drawn a distinction in, say, Kantian philosophy. Kant in his Critique of Practical Reason states the following (in his typical, idiosyncratic way):

[Concerning human agents], therefore, the moral law is an imperative, which commands categorically, because the law is unconditioned; the relation of such a will to this law is dependence under the name of obligation, which implies a constraint to an action, though only by reason and its objective law; and this action [through a priori rational principles] is called duty, because an elective will, subject to pathological affections (though not determined by them, and, therefore, still free), implies a wish that arises from subjective causes and, therefore, may often be opposed to the pure objective determining principle; whence it requires the moral constraint of a resistance of the practical reason, which may be called an internal, but intellectual, compulsion. (p32)

And later,

An action which is objectively practical according to [Moral] law, to the exclusion of every determining principle of inclination, is duty, and this by reason of that exclusion includes in its concept practical obligation, that is, a determination to actions, however reluctantly they may be done. (p82)

For Kant, a Duty is an action following from ideal rational ethical reflection on good practice, say through some ultimate value system, code of conduct, creed of membership or similar establishment of laws and rules. But Kant would hold that an Obligation is something related but distinct; specifically, Obligation is an independently normative relation between us as rational/practical moral agents and actions regardless of our relation to any particular systems or institutions. To say that I am morally obliged to carry out some form of action is to say that I ought to do it. For Kant, obligation is a matter of categorical necessity - you might have a hypothetical imperative to adhere to some framework of ethical action in order to be an accepted part of your community, but that wouldn't suffice in itself to constitute a moral obligation to act in a particular way.

This distinction seems important in Kantian ethics because he wants to put forward the claim that the correct form of a good will is one that acts in accordance with Duty qua Moral Law. We might split this up into two: we can have a positive disposition of character according to which one always acts in line with one's duties, and thereby exemplify a kind of "strength of will"; and we can have a motivation specifically to act in line with the duties that account for our moral obligations, as a contrast to all of the other duties to which we might be committed. We establish this kind of good will by a priori reason as to what the rules of good acting are and following them - that this is our moral obligation seems like something new, whereas it seems like a fairly natural analysis of what it would mean to establish and follow a moral duty.

The Kantian move is an important talking point in existentialism, where we might draw out a distinction between a life lived justly (i.e. satisfying moral principles) and a life lived respectably (i.e. satisfying social conventions and rules aimed at formally reconstructing those principles), say (though I'm not sure existentialists would use that same terminology). Existentialists like to pick at the idea that the rules are secondary to what the rules aspire to, and that living authentically may come apart from living according to a bad faith discipleship of the letter of the moral law. So there does seem to be some value in pulling duties and obligations apart conceptually, because it might be possible to make choices that satisfy one's moral obligations without living by a framework of duties.


Well this has been subject to various philosophical debates for a very long time. If you look at the definition of the two terms, you will get what seems like a circular answer. One refers to the other and the other refers back, case in point:

Definition of duty (n)

  • obligation: something that somebody is obliged to do for moral, legal, or religious reasons
  • need to meet obligations: the urge to meet moral or religious obligations
  • allocated task: a task or service allocated to somebody, especially in the course of work
  • Synonyms: responsibility, obligation, onus, burden, calling, liability

Definition of obligation (n)

  • duty: something that must be done because of legal or moral duty
  • state of being obligated: the state of being under a moral or legal duty to do something
  • gratitude owed: something that somebody owes in return for something given, e.g. assistance or a favor
  • Synonyms: duty, responsibility, requirement, compulsion, commitment, onus

Now you can see that in a way they are being defined interchangeably. However it seems that what separates the two are a matter of perspective and understanding of its context. Ironically what brings more light to this difference are the synonyms.

Observe that while some of the synonyms are the same, given the way they are defined not a real surprise, there are key differences in there that if they were truly the same would not happen.

The primary differences are:

  • burden (duty)
  • calling (duty)
  • liability (duty)
  • requirement (obligation)
  • compulsion (obligation)
  • commitment (obligation)

The trend of the differences for duty seem to imply that some part of the social contract is responsible for it. Duty to vote can be a burden to some and liability to others (the disenfranchised vs. those seeking future political office). Calling to be a soldier, cop, doctor, journalist, humanitarian, activist, etc etc (suggesting a familial trend - my father, his father, and his father ^n was a soldier so its my calling to serve, etc). So we can say perhaps that DUTY is born out of ideology or social contract which motivates the action with a sense of implied greater purpose.

Now looking at the differences for obligation seem to imply imposition of some of kind of responsibility out of legal, moral, or religious rules/laws. Obligation to obey traffic rules, caring for your offsprings, going to church, academic honor to not plagiarize or cheat, do not steal, do not kill, etc, you get the idea. We can perhaps see that obligation tends to come out of legal responsibility, moral or religious beliefs. The differences may seem subtle but they do include nuances that may be significant to how the individual behavior is guided.

  • "So we can say perhaps that DUTY is born out of ideology or social contract"; We can perhaps see that obligation tends to come out of legal responsibility, moral or religious beliefs." I don't think I can see the difference you're trying to illustrate. So legal responsibility has nothing to do with the social contract, and moral and religious beliefs aren't what you previously called "ideology"? You started explaining a difference, and then you didn't find it (or so it seems).
    – iphigenie
    Oct 2, 2013 at 23:56
  • @iphigenie, as I said, its a subtle distinction but there is a difference. For example, I come from a long line of soldiers, I mean LONG which means that every first born of my bloodline has served at the very least and that would be a duty if you will born out of ideology that if my ancestors did it, I am "destined" to do it as well. There is no social contract, legal statute, moral or religious obligation forcing me to do it, I do it because I feel that I must. See the distinction? However subtle? Oct 3, 2013 at 6:24
  • No. I think that this is an answer to vague to be answering anything. I'll ask you next why you feel that you feel that you must if there is no obligation (haha!), moral or political or whatever, that makes you want to fulfil that which you call your "duty". Either you admit that there is this moral "calling", then it is your moral obligation, or there is nothing but nagging relatives, but then you "can't feel that you must". You can't just say "there definitely is a distinction, even if no one can see it."
    – iphigenie
    Oct 3, 2013 at 8:02
  • @iphigenie, who says a calling is morality based? Something I did explain in my answer already. It is my obligation to acknowledge that you are entitled to your opinion as to the value of what I have said. I am not trying to convince anyone of anything other than to provide perspective. As an intelligent being with ability to think for myself, if I see a pattern of specific action, I can choose to form the thought to follow suit for my own reasons forming a sense of duty. It has nothing to do with nagging or morality or requirement. To each their own. Oct 3, 2013 at 16:41

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