Since we have spent some time with Hart's crucial distinction -- ESPECIALLY crucial for Oxonian speakers of Hart's generation -- it may do to review 'obligare' in Roman law. The thing is obviously a compound of 'ob-' and 'ligo' as in 'ligate' --. For Hart, 'oblige' is not necessarily legal or moral, and may just report a psychological episode involving motives (and reasons not having to do with legality or morality). It is the 'ligare' part of 'ob-ligare'. 'Obligate', on the other hand, makes reference to the realm of law and morality. In Rome, do as the Romans do. What things obligated them? What things obliged them? Obligare was, for the Romans, -- to bind or tie around -- to bind or fasten to any thing. obligatus corio -- "bound in a leathern sack" Auct. Her. 1, 13, 23 articulis muscus obligatus, "bound upon", Plinio 26, 11, 66, § 105: cibum ovis, "to bind or unite with eggs", Apic. 4, 2: amylo spisso obligare, id. 2, 2; 8, 2.— Nothing legal or moral about 'oblige' in: "The Roman matron obligated her slave to oblige the thing with eggs." -- which is the third quote above. --- Obligare is also to bind together, bind up: pecua ad hanc collo in crumena ego obligata defero, Plauto. Truc. 5, 1, 64: age obliga, obsigna cito, tie up the letter, in order to seal it, id. Bacch. 4, 4, 96: manipulos, Col. 11, 2, 40.— The Roman would say that he tied up the letter in order to seal it, and use 'obligare'. Nothing moral or legal about it. Just a common-or-garden variety of intentional action. Obligare is also to bind up, bandage, swathe (class., esp. of wounds): crus fractum, Plauto. Men. 5, 3, 9: vulnus, Cicerone. N. D. 3, 22, 57; cf.: medicum requirens, a quo obligetur, to bind up his wounds, id. Tusc. 2, 16, 38; Svetonio. Vit. 2: venas, to bandage the veins, Tac. A. 6, 9: surculum libro, Varrone R. R. 1, 41, 2: oculos, Sen. Ira, 3, 11, 4: ore obligato obsignatoque simulacrum, Plin. 3, 5, 9, § 65. Nothing moral or legal. These we may call the LITERAL uses of 'obligare'. They refer to a physical action performed intentionally by an agent. But obligare, at some time in Roman history, acquired a figurative extension. It came to be used to bind, TO OBLIGE (as the word is used by John Austin, if not Hart), put under an obligation, make liable, etc. (cf.: obstringo, devincio): aliquem obligare militiae secundo sacramento, bind by a second oath, swear in again, -- Here the use aequivocates on a case where Hart would not. Oblige/Obligated by a second oath. Cicerone. Off. 1, 11, 36: vadem tribus milibus aeris, to bind in the sum of, Livio. 3, 13: voti sponsio, quā obligamur deo, Cicerone. "Laws", Leg. 2, 16, 41; Livio 9, 11: se nexu, Cicerone Mur. 2, 3: se in acta cujusquam, Tiberio ap. Svetonio Tib. 67: se chirographo ad aliquid, Dig. 30, 103: aliquem sibi liberalitate, to bind to one's self, -- an interesting concept: self-oblige, self-obligate. Cicerone. Q. Fr. 2, 14, 3: obligabis me, will oblige me, lay me under an obligation, Plinio. Ep. 4, 4, 2; Cic. Q. Fr. 3, 1, 5: obligari foedere, Liv. 38, 33: pro amicis alicui obligari, to lay one's self under obligation, i. e. to solicit favours, --- If you solicit a favour, you lay yourself under obligation. If you are forced (or as John Austin, being slightly pretentious in his usage, coerced) to solicit a favour, you are obliged. If you provide a more subtle analysis of how obligation cashes in desire, you are obligated. Plinio. Ep. 10, 3, 1: obligor ipse tamen, Ovidio, Metamorphoses, 9, 248: obligatus ei nihil eram, was under no obligation to him, Cicero Fam. 6, 11, 1: me obligatum tibi fore, id. Att. 13, 18: obligati sunt interrogatum, Amm. 28, 4, 10. There is a poetic figurative extension. Prometheus obligatus aliti, -- as in Prometheus Bound and Prometheus UNbound. devoted, condemned to, Orazio Epod. 17, 67: ergo obligatam redde Jovi dapem, vowed, due, id. C. 2, 7, 17: obligor, ut tangam laevi fera litora Ponti, am compelled, Ovidio Tristia 1, 2, 83.— Recall taht Ovidio was obliged to leave Rome. Obligare could also mean, in this figurative extensive way, to mean to render liable through guilt, to make guilly: cum populum Romanum scelere obligāsses, Cicerone, Dom. 8, 20: votis caput, Orazio C. 2, 8, 5: se scelere, Svetonio, Giulio Cesare 42: se furti, Scaev. ap. Gell. 7, 15, 2. The passive voice usage was pretty common, in this figurative use, among the Romans. It was used to mean to be guilty of, to commit an offence: est enim periculum, ne aut neglectis iis impiā fraude, aut susceptis anili superstitione obligemur, Cicerone, Divinatione 1, 4, 7; cf.: lege Corneliā testamentariā obligatur, offends against, Dig. 8, 10, 30.— THEN there are the uses which, while still figurative, extensions from this physical literal sense of 'tying'. It has become, as with Hart, a 'term of art' -- only that Hart manages to find uses in ordinary language that turns his 'term of art' one that has backing in his exercise in 'linguistic botany'. Obligare is to bind, engage one (cf. obligatio, II. B.): obligandi, solvendi sui causā, Dig. 2, 13, 6, § 3: se obligare, ib. 4, 2, 7, § 1; 21, 1, 25, § 9.— Obligare can also mean, or rather, be used to express To pledge, pawn, mortgage a thing: magistratui bona ejus obligantur, Vitruvio 10 praef.: omnia praedia fratri, Svetonio, Vespasiano, 4: omnia bona sua pignori, Dig. 20, 4, 21: nam fundi et aedis obligatae sunt ob amoris praedium, has a mortgage on it, Plauto. Truc. 2, 1, 4: aedes pignori, Dig. 39, 2, 44: obligata praedia, Cic. Agr. 3, 2, 9.— There is a double figurative extension here, which is ripe for implicatural analysis, i.e. the use is based on the juridical extension, but goes beyond it -- it goes to the heart of morality. obligare fidem suam, to pledge one's word, Cicerone, Phil. 5, 18, 51.— Obligare was also used to mean to impede, restrain, embarrass: judicio districtum atque obligatum esse, Cicerone, Verr. 1, 9, 24. —Hence, "obligatus": bound, obliged (as taken up by first John Austin and then Hart. Hart will go on to refine Austin's incomplete analysis by trading on the oblige-obligate distinction. iisdem (officiis) me tibi obligatum fore, Cic. Fam. 13, 18, 2. Finally, there are uses which are comparative: quanto quis melior et probior, tanto mihi obligatior abit, Plinio, the Younger, Epistulae 8, 2, 8. And, it could also be used to yet differently, as in ipsi obligati sunt, ensnared, embarrassed, Vulg. Psa. 19, 9. The oblige-obligate distinction is considered to go to the heart (oops) of Hart's conceptual-analytic approach to legal philosophy. It is not the final word to it, since Hart goes on to analyse 'obligate', but not 'oblige', in terms of authority, and the scenarios get more and more complicated (which delights the conceptual analyst) when varieties of 'obligation' (now a noun) come to play a role. Other keywords needed in this conceptual analysis are then, notably, LEGITIMACY (as is obviously cognate with 'law', and so we have to be careful not to define law in term of legitimacy or vice versa) and AUTHORITY. Once you are equipped with the right methodological approach, you are on safe ground, because you can see the conceptual interdepence (and more importantly, the lack of it) in the fields of legal, moral, and political philosophy. Cheers, Speranza