¹ Restatement (Second) of Contracts §1 (1981) (“A contract is a promise or a set of promises …”).

² See, e.g., Raz, Joseph, Promises and Obligations, in Law Morality, and Society: Essays in Honor of H.L.A. Hart 210 (Joseph Raz & P. M. S. Hacker eds., 1977)Google Scholar, Charles Fried, Contract as Promise: A Theory of Contractual Obligation (1981); Dori Kimel, From Promise to Contract: Towards a Liberal Theory of Contract (2003); Shiffrin, Seana Valentine, The Divergence of Contract and Promise, 120 Harv. L. Rev. 708 (2007) (hereinafter, “Divergence”)Google Scholar; Kraus, Jody, The Correspondence of Contract and Promise, 109 Colum. L. Rev. 1603 (2009)Google Scholar; Pratt, Michael G., Contract: Not Promise, 35 Fla. St. U. L. Rev. 801 (2008)Google Scholar; Shiffrin, Seana, Is a Contract a Promise? in Routledge Companion to Philosophy of Law (Andrei Marmor ed., 2012)Google Scholar; Scanlon, T. M., Promises and Contracts, in The Theory of Contract Law: New Essays 86 (Benson, Peter ed., 2001)CrossRefGoogle Scholar.

³ Many scholars in the law and economics tradition have sought to de-emphasize the promissory principle, see, e.g., Craswell, Richard, Contract Law, Default Rules, and the Philosophy of Promising, 88 Mich. L. Rev. 489 (1989)Google Scholar, and other scholars try to retain the importance of the promissory principle even while making room for other values too, see, e.g., Kraus, Jody, Reconciling Autonomy and Efficiency in Contract Law: The Vertical Integration Strategy, 11 Phil. Issues 420 (2001)CrossRefGoogle Scholar.

⁴ See generally P.S. Atiyah, The Rise and Fall of Freedom of Contract (1979).

⁵ See generally Barnett, Randy E., Contract Is Not Promise; Contract is Consent, in Philosophical Foundations of Contract Law 42 (Klass, Gregory, Letsas, George, & Saprai, Prince eds., 2014)Google Scholar.

⁶ See generally Hanoch Dagan & Michael Heller, The Choice Theory of Contracts (2017); Roy Kreitner, On the New Pluralism in Contract Theory, 45 Suffolk Univ. L. Rev. 915 (2012); Howard M. Erichson & Ethan J. Leib, Class Action Settlements as Contracts?, 102 N.C. L. Rev. 73 (2024); Aditi Bagchi, Pluralism, in Research Handbook in the Philosophy of Contract Law (forthcoming 2024), available at https://papers.ssrn.com/sol3/papers.cfm?abstract_id=4459627.

⁷ See generally Herbert J. Schlesinger, Promises, Oaths, and Vows: On the Psychology of Promising 173–198 (2008). A short and thoughtful effort to try to distinguish vows and oaths from promises appears in Martin Hogg, Promises and Contract Law: Comparative Perspectives 38–45 (2011). As I will make clear below, the laudable summaries there miss some pretty important realities about the histories of these practices; how widespread they likely were even outside of strictly religious contexts; and how tied up with law they have long been. Hogg treats vows as “specialized” to biblical and medieval contexts so rules concerning vows “can only have been of very restricted influence so far as the overall impact of promissory idea on contract law was concerned.” Id. at 41. While he concedes the legal significance of oaths even in modern law, he probably understates their centrality in the development of contract, assuming that all breaches of oaths triggered only ecclesiastical jurisdiction, removed from civil justice and the ultimate common law of contracts. Id. at 41–45. See also Joseph Raz, Is There a Reason To Keep a Promise?, in Philosophical Foundations of Contract Law, supra note 5, at 58, 65 (acknowledging that vows and oaths “differ from promises in many ways, among them the fact that … they are established by law or custom” and that people using them “undertake duties whose content is determined by law or custom” with “restrictive qualifications for being able to undertake these obligations” and with “strict conditions for being released from them”) (citing no history or any authority); Dori Kimel, Personal Autonomy and Change of Mind in Promise and in Contract, in Philosophical Foundations of Contract Law, supra note 5, at 96, 97 (“Unlike, say, a vow, or other putative forms of personal undertakings, a promise is made to someone; it involves a promisee.”) (citing no history or any authority); James Penner, Promises, Agreements, and Contracts, in Philosophical Foundations of Contract Law, supra note 5, at 116, 130 (assimilating oaths and vows to promises—as not really “upping the ante”).

⁸ Although D.J. Ibbetson, A Historical Introduction to the Law of Obligations (1999) at first seems to treat oaths as a mere footnote to the common law of contract because in his quick summary oaths “attracted no human sanction,” id. at 4, he later concedes that the very birth of the cause of action that became breach of contract in the sixteenth century (assumpsit) could be traceable to “some transplantation of language and ideas from the ecclesiastical courts to the secular courts,” id. at 136. I will discuss this development infra Part III.

⁹ Fried, supra note 2, at 41–43, seeks to distinguish vows from promises without usefully defining vows other than claiming they need not be communicated to any beneficiary. Fried offers no support for that proposition nor does he offer any engagement with any literature about vows. I assume his marriage vows, like most, were communicated to their beneficiary. Atiyah, for his part, also very quickly offers some ruminations on vows without any consistent definition or engagement in study. See P. S. Atiyah, Promises, Morals, and Law 54 (1981).

¹⁰ Legal academics have not ignored these oaths. See, e.g., Lee, Youngjae, Punishing Disloyalty? Treason, Espionage, and the Transgression of Political Boundaries, 31 Law & Phil. 299, 323–338 (2012)CrossRefGoogle Scholar; Silving, Helen, The Oath: II, 68 Yale L.J. 1527 (1959)CrossRefGoogle Scholar; Richard M. Re, Promising the Constitution, 110 Nw. U. L. Rev. 299 (2016); Milhizer, Eugene R., So Help Me Allah: An Historical and Prudential Analysis of Oaths as Applied to the Current Controversy of the Bible and Quran in Oath Practices in America, 70 Ohio St. L.J. 1 (2009)Google Scholar; Jonassen, Frederick B., “So Help Me?”: Religious Expression and Artifacts in the Oath of Office and the Courtroom Oath, 12 Card. Pub. L. Pol'y & Ethics J. 303 (2014)Google Scholar; Gallacher, Ian, “Swear Not at All”: Time to Abandon the Testimonial Oath, 52 New Eng. L. Rev. 247 (2018)Google Scholar; Knudsen, Kathleen M., The Juror's Sacred Oath: Is There a Constitutional Right to a Properly Sworn Jury?, 32 Touro L. Rev. 489 (2016)Google Scholar. For recent contributions to the historical study of oath practices, see Andrew Kent, Ethan J. Leib, & Jed Shugerman, Faithful Execution and Article II, 132 Harv. L. Rev. 2111, 2141–2178 (2019); and Ethan J. Leib & Andrew Kent, Fiduciary Law and the Law of Public Office, 62 Wm. & M. L. Rev. 1297 (2021).

¹¹ By invoking a genealogical method here, I have in mind an effort to use history to both “defamiliarize” the predominance of promising as such within contract and “reconceptualize” vows and oaths as relevant to contract morphology, looking at family resemblances with other volitional institutional practices that predate and might inform contract. See Derek Hook (with Brett Bowman), Foucault's ‘Philosophy of the Event’: Genealogical Method and the Deployment of the Abnormal, in Foucault, Psychology and the Analytics of Power 138 (2007). Although history is certainly relevant in this critical project, I am not seeking to decisively support a causal claim. As Foucault himself suggests, genealogy “opposes itself to the search for ‘origins’.” Michel Foucault, Nietzsche, Genealogy, History, in Language, Counter-Memory, Practice: Selected Essays and Interviews 139, 140 (D. F. Bouchard ed., 1977).

¹² See Fruh, Kyle, Promising's Neglected Siblings: Oaths, Vows, and Promissory Obligation, 100 Pac. Phil. Q. 858 (2019)CrossRefGoogle Scholar. Nothing, it seems, turns here on taxonomic rank; whether promises, oaths, and vows are “siblings” or in the same genus or species should not matter for a promise pluralist.

¹³ E.g., Atiyah, supra note 9, at 54; Hogg, supra note 7, at 38–45. For an argument that most vows don't trigger obligations, see Allen, Anita L., Vowing Moral Integrity, 19 Eu. J. App. Phil. 2, 21–22 (2023)Google Scholar.

¹⁴ E.g., David Owens, Shaping the Normative Landscape 171, 223 (2014) (although only provisionally committing to a theory of vows, defining them as obligations one takes only upon oneself, inwardly directed, and with no provision for release—all unlike promises on his view).

¹⁵ E.g., Kimel, supra note 7, at 97; Bagchi, supra note 6, at 3. There is something a little puzzling about this way of distinguishing vows and promises, since our most common vows in ethical life—marriage vows—are made directed to others, a point appreciated by Raz, supra note 7, at 65. And there is reason to think, in any case, that self-promising is more legible than is usually appreciated by promissory theorists. See Habib, Alan, Promises to the Self, 39 Can. J. Phil. 537 (2009)CrossRefGoogle Scholar; Connie Rosati, The Importance of Self-Promises, in Promises and Agreements: Philosophical Essays (Hanoch Sheinman ed., 2011); Kyle Fruh, The Power to Promise Oneself, 52 S. J. Phil. 61 (2014). Although often made to divine authority, oaths are also routinely done publicly, as if to indicate that others may hold those who swear accountable.

¹⁶ R.F. Johnston, Vows (Chinese), in XII Encyclopaedia of Religion and Ethics 646 (James Hastings et al. eds., 1962).

¹⁷ Id.

¹⁸ These functions of form are well known to contract theorists from Fuller, Lon, Consideration and Form, 41 Colum. L. Rev. 799 (1941)CrossRefGoogle Scholar. In his article, Fuller mostly took the promissory theory for granted, mentioning promises more than 100 times but not once considering the cautionary, evidentiary, and channeling functions of vows or oaths. Fuller is also associated with “reliance” theorists, given his other major contribution to contract theory. See L.L Fuller & William R. Perdue, The Reliance Interest in Contract Damages: 1, 46 Yale L.J. 52 (1936); L.L Fuller & William R. Perdue, The Reliance Interest in Contract Damages: II, 46 Yale L.J. 373 (1937). For the use of Fuller to understand rituals in law, see Tiersma, Peter Meijes, Rites of Passage: Legal Ritual in Roman Law and Anthropological Analogues, 9 J. Legal Hist. 3, 15 (1988)CrossRefGoogle Scholar.

¹⁹ Quoted in Johnston, supra note 16, at 647.

²⁰ Id.

²¹ See A. E. Crawley, Oath (Introductory and Primitive), in IX Encyclopaedia of Religion and Ethics, supra note 16, at 430.

²² Id.

²³ See Silving, Helen, The Oath: I, 68 Yale L.J. 1329, 1330 (1959)CrossRefGoogle Scholar.

²⁴ See Maurice A. Canney, Oath (Semitic), in IX Encyclopaedia of Religion and Ethics, supra note 16, at 436; Lehmann, Manfred R., Biblical Oaths, 81 Zeitschrift für die Alttestamentliche Wissenschaft 74, 76, 78–80 (1969)CrossRefGoogle Scholar.

²⁵ See Silving, supra note 23, at 1330, 1336–1337.

²⁶ Crawley, supra note 21, at 430–433

²⁷ E.g., Fried, supra note 2, at 7–17.

²⁸ Crawley, supra note 21, at 433.

²⁹ Id.

³⁰ See Canney, supra note 24, at 436 n.2, 437; see also W. Ernest Beet, Oath (NT and Christian), in IX Encyclopaedia of Religion and Ethics, supra note 16, at 435. (“As time went on, the oath, in ever growing measure, became a factor in almost every social relationship; e.g., in addition to the judicial oath, guaranteeing truth, may be mentioned those pledges of fidelity, the oath of fealty, the coronation oath, and the oath of office more generally. This was the case in ecclesiastical no less than in civil life, as witness ordination oaths, monastic and crusaders’ vows.”)

³¹ Id.

³² A. C. Pearson, Vows (Greek and Roman), in XII Encyclopaedia of Religion and Ethics, supra note 16, at 652 (emphasis added).

³³ Id.

³⁴ Id. at 653.

³⁵ Silving, supra note 23, at 1337.

³⁶ Id. Silving also describes “decisory” oaths, which one party could offer another to resolve an issue and “suppletory” oaths, which are offered by a judge to one party to help buttress its case. Id. Far from oaths being extra-legal here, they were heavily wrapped up in legal procedures. Even the oath of office was a mode of changing legal status. Silving traces this tie to legal procedure through Germanic law in id. at 1340–1343. For its role in early modern English legal history, see Conal Condren, Argument and Authority in Early Modern England: The Presupposition of Oaths and Offices (2006).

³⁷ See Hogg, supra note 7, at 112 nn.7 & 9 (identifying a spondere formulation in the standard early stipulatio as associated with oaths), citing Reinhard Zimmerman, The Law of Obligations: Roman Foundations of the Civilian Tradition 71 (1996).

³⁸ Pearson, supra note 32, at 652 (citing Plato, The Laws 909e).

³⁹ Id. at 653.

⁴⁰ Mann, Jacob, Oaths and Vows in the Synoptic Gospels, 21 Am. J. Theo. 260, 260 (1917)Google Scholar.

⁴¹ For an important effort in this regard, see James Endell Tyler, Oaths: Their Origin, Nature, and History (1834).

⁴² A.J. Grieve, Vows (Christian), in XII Encyclopaedia of Religion and Ethics, supra note 16, at 650.

⁴³ Id. at 651.

⁴⁴ Id.; see also Richard H. Helmholz, 1 The Oxford History of the Laws of England: The Canon Law and Ecclesiastical Jurisdiction from 597 to the 1640s, at 418–420 (2004); Hogg, supra note 7, at 120.

⁴⁵ E.g., Alaska Packers’ Ass'n v. Domenico, 117 F.99 (1902) (holding that a pre-existing duty to do a job for one price vitiates the possibility of agreeing to do the same thing for a new commitment to pay more money for the same performance).

⁴⁶ E.g., Restatement (Second) of Contracts §§178–199 (1981).

⁴⁷ See Matthew 5:33–37.

⁴⁸ See Johnston, supra note 16, at 646.

⁴⁹ See Saul Lieberman, Greek in Jewish Palestine 115 (1994 [1942]).

⁵⁰ See John E. McFadyen, Vows (Hebrew), in XII Encyclopaedia of Religion and Ethics, supra note 16, at 654; Moshe Benovitz, Kol Nidre: Studies in the Development of Rabbinic Votive Institutions 24 (1998) (arguing that oaths in contravention of biblical law are void ab initio). To some extent, Jewish law developed otherwise and a codification of Jewish law in the sixteenth century permitted vowing to fortify oneself to fulfill a positive commandment or to avoid a negative commandment. See Shulchan Aruch, Yorah Deah 203. The oath, however, seems not to be valid “if one swears either to fulfill or to violate any of the provisions of the Sinaitic covenant,” because “the entire people of Israel has already sworn to fulfill them at Sinai.” Lawrence H. Schiffman, The Law of Vows and Oaths (Num. 30, 3–16) in the Zadokite Fragments and the Temple Scroll, 15 Revue de Qumran 199, 202 (1981).

⁵¹ See Numbers 6: 1–21. John the Baptist and Paul were both Nazirites, partaking in this vow. See Luke 1:15 (John the Baptist); Acts 18:18, 21:23–26 (Paul).

⁵² See McFadyen, supra note 50, at 656.

⁵³ Id. at 654; see also Benovitz, supra note 50, at 9 (“The biblical vow is usually conditional”) (citing Genesis 28:20–22 (Jacob vows to God if he watches over his journey); and I Samuel 1:11 (Hannah offers a son to service if God gives her a son); id. at 130–131 (the oath is conditional, too); Lehmann, supra note 24, at 80 (the oath is a “conditional curse going into effect only when the oath is broken”); id. at 85–86 (the vow is also a “measure for measure” exchange).

⁵⁴ See McFadyen, supra note 50, at 655.

⁵⁵ See, e.g., Deuteronomy 11:13–21.

⁵⁶ McFadyen, supra note 50, at 654–655.

⁵⁷ Id. at 654.

⁵⁸ See Leviticus 27:9–25.

⁵⁹ See Schiffman, supra note 50, at 201 (citing 1 Sam. 14:45 for the view that “an oath could be set aside if a sum was donated to the Temple”). This is not to say there was no conception of “specific performance” for forcing one to perform his vow in certain circumstances. See BT Kiddushin 50a (“With respect to one who vows to bring an olah sacrifice, the verse states ‘he shall bring it.’ This teaches that we coerce him to fulfill his vow.”) (citing Leviticus 1:3).

⁶⁰ Lehmann, supra note 24, at 74.

⁶¹ Id.

⁶² Id. at 84. For some examples in the Old Testament, see Numbers 5:21, 27 (curses associated with the secluded wife and jealous husband ceremony (sotah); Genesis 26: 28 (oaths associated with entering a treaty). There is another word in the Hebrew Bible—berit—that might be relevant to this reconstruction effort. It often translates as “covenant” but there might be warrant to think of it more as a “pact” or “obligation.” See Weinfield, M., Berit—Covenant vs. Obligation, 56 Biblica 120 (1975)Google Scholar. Although one might be able to trace a line that translated berit with pactum in Latin sources drawing the concept closer to contract, the Jewish rabbinical tradition never developed the conception of berit into an operational legal idea. Trying to link covenantal community to the law of contract is a subject for another day. There is certainly warrant to draw oaths and covenants closer in the Hebrew Bible: in Isaiah 54:9, God uses the language of having sworn matters (nishbati) to Noah—but Genesis treats God's representations in the language of covenant (berit), see Genesis 9:9–17 (invoking berit five times). The covenant with Abraham also uses the language of berit—but, like the relationship with Noah, it feels as if it too is in exchange for fealty (and is later rendered in the language of oath (shevuah)): see Deuteronomy 11:21.

⁶³ See Lieberman, supra note 50, at 117 (“[I]n practice, the people seem not to have discriminated between these two terms,” though there was a theoretical difference in that the oath was seen as a “personal obligation to do or not do something,” “whereas a vow makes an item forbidden to the person.”). See also Falk, Zeev W., On Talmudic Vows, 59 Harv. Theo. Rev. 309, 309 (1966)Google Scholar (conceding “a basic difference between vows and oaths, though both are sometimes formulated in a similar way”); Shulchan Aruch, Choshen Mishpat 207:19 (announcing that vows and oaths and handshake deals are all similarly acceptable validation devices for transactions). There is some reason to think that a conditional self-imposed curse model of the oath, see Benovitz, supra note 50, at 127 (“an oath is a curse to which the swearer subjects himself in the event that his words prove false: in a future-tense oath, the curse is to take effect if and when the oath is violated; in a past-tense oath, the curse is to take effect if the statement made is untrue”), renders it more difficult to justify empowering rabbis to dissolve them, id. at 164. That is subject to some debate among the Rabbis in the Talmud, however, some of whom took the view that the oath could be dissolved just like vows could be. Benovitz essentially needs to concede that is the dominant position of the authoritative Babylonian Talmud, which incorporates a position credited to one rabbi in the Palestinian Talmud (PT Nedarim 11:1, 42c). See id. (citing BT Shevuot 27b; Nedarim 28a; Ketubot 77b; Sotah 36b; Sanhedrin 38a). There are definitely moments in the Babylonian Talmud that reinforce the view that a false oath was more troubling to the Rabbis than a vow—and they tried to channel people into vowing rather than swearing. See, e.g., BT Gittin 34b–36a. But see PT Gittin 4:3 (suggesting that vows were feared more than oaths).

⁶⁴ Morris Joseph, Vows (Jewish), in XII Encyclopaedia of Religion and Ethics, supra note 16, at 657.

⁶⁵ See Lieberman, supra note 50, at 115.

⁶⁶ See Philo, II On Special Laws III(9)–IV(17).

⁶⁷ See E. Allan Farnsworth, Changing Your Mind: The Law of Regretted Decisions 20 (1998).

⁶⁸ See Lieberman, supra note 50, at 116 (“The people swore and adjured on every occasion; they affirmed their statements by an oath in business affairs, in formulas of courtesy when they invited their friends, accepted invitations or rejected them, and in support of stories which strained credulity”); Mann, supra note 40, at 267 n.1 (listing examples from the Talmud of the use of vows to disinherit children).

⁶⁹ See BT Nedarim 2a ff. (highlighting that a vow can be taken on with all manner of equivalences); BT Nazir 2a ff (highlighting that if someone says they are a “nazik” or a “naziach” or a “paziach,” he took on the vow of being a Nazirite).

⁷⁰ E.g., Fried, supra note 2, at 7–17.

⁷¹ Long after the Rabbis expansively interpreted the language of vows, more contemporary legal systems sought to retain narrowly drawn testimonial oaths and not permit departures from their formulations. See Silving, supra note 23, at 1355.

⁷² See Mishnah Nedarim 3; BT Shevuot 26a–b.

⁷³ See Lieberman, supra note 50, at 142–143 (citing PT Nedarim 3:5; Cicero, De Officiis III XXIX 107).

⁷⁴ Joseph, supra note 64, at 658.

⁷⁵ Id.; see also Mann, supra note 40, at 272 (“Yet seeing the great necessity of this device [of annulling vows] for the welfare of the people, the [Rabbis] clung to the innovation and helped to make it the accepted opinion and practice.”).

⁷⁶ See generally Benovitz, supra note 50, at 149–164 (on the annulment of vows and oaths in rabbinical literature); id. at 165–176 (on the annual prayer which accomplishes annulments of both vows and oaths).

⁷⁷ See Matthew 5:33–37.

⁷⁸ See Midrash Tanchuma, Vayikra 7: “Let not someone from Israel be unrestrained in vows or in jesting (or to lead one's companion astray with an oath by saying it is not an oath). There is a story about the royal mountain where there were two thousand towns, and all of them were destroyed because of a truthful oath that was unnecessary. Now if one who swears in truth has this happen, how much the more so in the case of one who swears to a lie?”

⁷⁹ One reader suggested to me a counterexample in Ruth 1: 16, in which Ruth famously declares to her mother-in-law: “wherever you go, I will go; wherever you lodge, I will lodge.” Perhaps this statement is plausibly conditional—but not bilateral because on its face it requires nothing of Naomi. The reason I don't think this succeeds as a counterexample (though I'm sure there are some) is twofold. First, nothing in the Hebrew text suggests this declaration is a vow (neder) or an oath (shevuah). Second, even if it were, it actually is an instance of Ruth bargaining; the context of the passage is Ruth begging Naomi not to urge her to leave and this declaration is meant to incentivize (as it does, see Ruth 1:18) Naomi to stop arguing with her to return to her people and gods (as her sister-in-law Orpah does).

⁸⁰ But see Hogg, supra note 7, at 39 (arguing from a Thomistic viewpoint that vows always require strict fulfillment and are only made to god).

⁸¹ For a conventional analytical definition of promise, see id. at 64 (“a statement by which one person commits to some future beneficial performance (or the beneficial withholding of a performance) in favour of another person”). There are other differences between vows and oaths on the one hand and promises on the other one could emphasize using Hogg's definition: vows and oaths, in this definition, do not focus on another person per se in the way his definition of promise requires, accord Fruh, supra note 12, at 860, though many cases of vows and oaths do in fact trigger another's right of redress for default and are other-directed. True enough, the contemplated “authority” in the analytical definition need not be the state. But that enforceability matters already draws vows and oaths closer to contract than its “sibling” mere promise.

⁸² For a review of Selden's engagement with Jewish law, see Jason P. Rosenblatt, John Selden: Scholar, Statesmen, Advocate for Milton's Muse (2021); Jason P. Rosenblatt, Renaissance England's Chief Rabbi: John Selden (2008); Jason Rosenblatt, Rabbinic Ideas in the Political Thought of John Selden, in Political Hebraism: Judaic Sources in Early Modern Political Thought (Gordon Schochet, Fania Oz-Salzberger, & Meirav Jones eds., 2008); Isaac Herzog, John Selden and Jewish Law, 13 J. Comp. & Int'l L. 236 (1931) (arguing that Selden evidences substantial familiarity with rabbinic law but also some non-Talmudic ways of thinking). For confirmation that Selden knew the law of vows and oaths particularly, see id. at 241; John Selden & Samuel Weller Singer, The Table-talk of John Selden 200–02 (J. Russell Smith ed., 3rd ed. 1860) (entry on “Oaths” discussing the rabbinical laws of annulling vows); John Selden, 1 De Synhedriis & Praefecturis Iuridicus Veterum Ebraeorum (1646) (translated in part as “The Synedria and Judicial Institutions of the Ancient Hebrews” by Peter Wyetzner on commission from The Shalem Center, on file with author); G.J. Toomer, II John Selden: A Life in Scholarship 449, 748–751 (2009). Toomer confirms that false oaths could lead to civil legal punishments, not just damnation. See id. at 750.

⁸³ For some work in this vein, see Eric Nelson, The Hebrew Republic: Jewish Sources and the Transformation of European Political Thought (2010); Slate, Daniel D., Franklin's Talmud: Hebraic Republicanism in the Constitutional Convention and the Debate over Ratification, 1787–1788, 1 J. Am. Con. Hist. 232 (2023)Google Scholar. For a takedown of John Milton's superficial knowledge of Jewish law, see Leonard R. Mendelsohn, Milton and the Rabbis: A Later Inquiry, 18 Studs. in Eng. Lit. 125 (1978).

⁸⁴ England essentially expelled its Jews in 1290 under Edward I. They were not resettled until Oliver Cromwell in the 1650s. That makes Selden's accomplishments all the more impressive and rare.

⁸⁵ See generally J.G.A. Pocock, The Ancient Constitution and the Feudal Law: English Historical Thought in the Seventeenth Century (1957). For discussion, see Ziskind, Martha A., John Selden: Criticism and Affirmation of the Common Law Tradition, 19 Am. J. Legal Hist. 22 (1975)CrossRefGoogle Scholar.

⁸⁶ On their role in the law of public office especially, see Kent, Leib & Shugerman, supra note 10; and Leib & Kent, supra note 10.

⁸⁷ See Theodore F.T. Plucknett, A Concise History of the Common Law 112–113 (2010) (1929).

⁸⁸ Id. at 113–116. See also Silving, supra note 23, at 1361 (arguing that the jury trial came out of oath practices); id. at 1363 (arguing that the oath system was “rationalized” because it had its own power that wasn't reliant on divine intervention); Sir Frederick Pollock & Frederic William Maitland, 2 The History of English Law Before the Time of Edward I, at 224 (2010) (1898) (discussing the use of oaths and “oath-helpers” in debt cases); Farnsworth, E. Allan, The Past of Promise: An Historical Introduction to Contract, 69 Colum. L. Rev. 576, 594 (1969)CrossRefGoogle Scholar.

⁸⁹ Plucknett, supra note 87, at 116–38. On the abolition of compurgation, see Statute of 3 & 4 Will. 4, c. 42, §13 (1833).

⁹⁰ Id. at 363.

⁹¹ See Ibbetson, supra note 8, at 71.

⁹² Id. at 72–73.

⁹³ Plucknett, supra note 87, at 628–629. Some of these ceremonies with formalities—such as the stipulatio—sometimes partook of a promissory institution too. See Tiersma, supra note 18, at 8, 17. Some have seen this promissory institution as connected to oaths, in particular. See Hogg, supra note 7, at 112 nn.7 & 9.

⁹⁴ See Hibbitts, Bernard J., “Coming to Our Senses:” Communication and Legal Expression in Performance Cultures, 41 Emory L.J. 873 (1992)Google Scholar; Ibbetson, supra note 8, at 75.

⁹⁵ See id. at 28–30, 92; A.W.B. Simpson, A History of the Common Law of Contract: The Rise of the Action of Assumpsit 90-126. The centrality of the bond structure—so similar to the vow—to the American common law of contract until the nineteenth century is emphasized by Jody P. Kraus & Robert E. Scott, The Case Against Equity in American Contract Law, 93 S. Cal. L. Rev. 1323, 1334–1337 (2020).

⁹⁶ Ibbetson, supra note 8, at 93–94.

⁹⁷ Christopher St. Germain, Doctor and Student dia II, c. 24 (1530).

⁹⁸ See, e.g., Ibbetson, supra note 8, at 130–131, 137 (citing Pykeryng v. Thurgoode (1532) 94 SS 247).

⁹⁹ See Ibbetson, supra note 8, at 83.

¹⁰⁰ Id. at 138.

¹⁰¹ Plucknett, supra note 87, at 643–646; see also David Ibbetson, Sixteenth Century Contract Law: Slade's Case in Context, 4 Ox. J. Legal Studs. 295 (1984).

¹⁰² Oliver Wendell Holmes, Jr., The Common Law 264 (1991) (1881); see also Atiyah, supra note 9, at 119.

¹⁰³ Ibbetson, supra note 8, at 135.

¹⁰⁴ Id. at 139–140.

¹⁰⁵ Id. at 136: “The very fact that lawyers came to use [promise] so consistently at least raises the possibility that they meant something by it.” But see Hogg, supra note 7, at 109, arguing that the real story about promise is about its “eclipse” from “Western legal systems” that “dwindled in importance” from the seventeenth century onwards.

¹⁰⁶ Ibbetson, supra note 8, at 145.

¹⁰⁷ See Helmholz, R.H., Assumpsit and Fidei Laesio, 91 Law Q. Rev. 406 (1975)Google Scholar.

¹⁰⁸ Ibbetson, supra note 8, at 136.

¹⁰⁹ Id. at 136–137. See also Hogg, supra note 7, at 42 (conceding important conceptual overlaps between oaths and promises).

¹¹⁰ See Richard H. Helmholz, Contracts and the Canon Law: Possible Points of Contact Between England and the Continent, in Towards a General Law of Contract 49 (John Barton ed., 1990).

¹¹¹ Helmholz, supra note 107, at 421; Hogg, supra note 7, at 124–125. Perhaps little of this would be surprising to some of the earliest and best-known historians of the common law of contract who traced its roots to oath-like practices with the use of hands and found its “essence” in “fides” or “faith.” See Pollock & Maitland, supra note 88, at 196–197, explaining the idea of the use of hands as follows: “As I here deliver myself to you by my right hand, so I deliver myself to the wrath of Fides … if I break faith in this thing.” Although Pollack and Maitland see this root of contract as “sacral,” and therefore not yet subject to legal enforcement, the arc of their history is from a binding contractual ceremony of the fides facta (with this oath-like or vow-like structure) to enforcement by the Church to the common law. That story resonates with Samuel von Pufendorf, too. See Hogg, supra note 7, at 133, identifying Pufendorf as tracking agreements “backed by oath” to “general civil enforcement.”

¹¹² See Simpson, supra note 95, at 389 (discussing the “advow”—a votive institution of a promise made to god—as it is discussed in St. Germain, supra note 97, at Ch. 24 (though Simpson cites Chapter 23)).

¹¹³ For one effort by a promissory theorist to offer a “genealogy of promise” (by which he means “demonstrating how [promise] could have evolved by a series of steps that each make sense, whether or not it actually came about in that fashion”), see Owens, supra note 14, at 159.

¹¹⁴ Obviously, there are plenty of theorists who find the moralism of promissory theory altogether worth abandoning. See, e.g., Fried, Barbara H., What's Morality Got To Do with It?, 120 Harv. L. Rev. F. 53 (2007)Google Scholar. One interesting effect of the discovery that the “Holmesian” idea of pay-or-perform was already immanent in the law of vows is that we can tie it to a pre-existing ecosystem that wove law and morality together, see P.S. Atiyah, Holmes and the Theory of Contract, in Essays on Contract 57–72 (1986).

¹¹⁵ Shiffrin, Divergence, supra note 2, at 710; see also Hogg, supra note 7, at 38 (arguing that a pure promissory theory would have all unilateral and gratuitous promises enforced at law). To be fair, some promissory theorists seek to solve this problem by defining a promise to require some kind of acceptance or performance by the promisee induced by the promise. See Owens, supra note 14, at 224–225. That seems in tension with contract law, too. If the nephew in Hamer v. Sidway, 124 N.Y. 538 (1891), had been blotto when his uncle made him the promise for $5,000 to turn his life around—and the nephew turned his life around the next morning not because he remembered anything about the uncle's promise but because he was ashamed that he got wasted at his parents’ anniversary party, few think the law wouldn't award him the money.

¹¹⁶ Fried, supra note 2, at 17.

¹¹⁷ See generally Craswell, Richard, When is Willful Breach “Willful”? The Link Between Definitions and Damages, 107 Mich. L. Rev. 1501 (2009)Google Scholar (exploring bad faith in contract law); Kimel, supra note 7, at 103 (promissory approaches to contract impliedly are committed to strict liability). Kimel himself thinks promissory theory can be reconciled with fault-based contract law. See id. at 105.

¹¹⁸ Jacob & Youngs v. Kent, 230 N.Y. 239, 244 (1921). I always like to imagine Cardozo was inspired by the Day of Atonement services in light of his membership at Congregation Shearith Israel. But he very much distanced himself from temple-going after his Bar Mitzvah in 1883. See Andrew L. Kaufman, Cardozo 24–25 (1998). He did seem to come back to the synagogue on matters of governance and tradition, though. Id. at 69–70 (making a speech to sustain segregation of the sexes, opposing a reform to the seating rules in the sanctuary); id. at 189 (reflecting on the meaning of religion at a celebration for his childhood rabbi). Those haunting tunes from Kol Nidre night, however, are not easily forgotten from youth. Linking Kol Nidre to Cardozo's contract law will have to await a future project.

¹¹⁹ See Liam Murphy, The Practice of Promise and Contract, in Philosophical Foundations of Contract Law, supra note 5, at 151, 156–157; Shiffrin, Divergence, supra note 2, at 722–724.

¹²⁰ Shiffrin also discusses the mitigation doctrine—that the aggrieved party in a contractual breach is required to mitigate damages, a rule that isn't easy to reconcile with promissory morality, she argues. Id. at 724–726. I am not certain that this particular divergence is actually quite so damning from the standpoint of promissory theory since promissory morality could probably be rendered consistent with the basic principle of mitigation. Shiffrin's discussion of the divergences that might be on display in the rules about punitive and liquidated damages indicate that even she isn't really sure those rules diverge from promissory morality either. See id. at 726–727. For general agreement that these areas of divergence are not particularly troubling to promissory theorists, see Liam Murphy, Contract and Promise, 120 Harv. L. Rev. F. 10, 16–17 (2007). Murphy, to be fair, is even doubtful that the damages remedy is a divergence—but I think he is in the minority on that.

¹²¹ One might add to the list the concept of duress, “which the promissory regime treats as [an] anomal[y].” See Charles Fried, The Ambitions of Contract as Promise, in Philosophical Foundations of Contract Law, supra note 5, at 17, 19. As discussed previously, the vow and oath regimes already had rules for using duress as a basis for excuse. Similarly, some of the doctrines of so-called “paternalism” that seem “inconsistent with the promissory principle” (see id. at 35) might have their roots in some of the rules surrounding vows and oaths and are therefore not extrinsic to the moral ecology of contract-as-vow-or-oath.

¹²² See Simpson, supra note 95, at 242–247 & 253–258; Plucknett, supra note 87, at 640–643; Pollock & Maitland, supra note 88, at 25. See also Ibbetson, supra note 8, at 88–91 (discussing how the fault-based law of tort made its way into contract law).

¹²³ See generally Fault in American Contract Law (Omri Ben-Shahar & Ariel Porat eds., 2010); Good Faith and Fault in Contract Law (Jack Beatson & Daniel Friedmann eds., 1995); Cohen, George M., The Fault Lines in Contract Damages, 80 Va. L. Rev. 1225 (1994)CrossRefGoogle Scholar. Daniel Markovits has sought—qua promissory theorist—to explain good faith as contract's core value. See Daniel Markovits, Good Faith as Contract's Core Value, in Philosophical Foundations of Contract Law, supra note 5, at 272. The claim here is that it fits well with the causes of action that came from the fidei laesio, rooted in oaths. See Helmholz, supra note 107.

¹²⁴ The kinds of promises that were enforced originally were the ones undertaken “faithfully” (see id. at 419), which might be a source of good faith duties; see also Ibbetson, supra note 8, at 136–137.

¹²⁵ There is some evidence that the original promissory theorist has conceded that the links between the promissory principle and actually existing contract law were “overstated.” Fried, supra note 121, at 34. Fried's concessions, however, are ultimately grounded in the view that much about contract law that doesn't comport with the promissory principle comprises features merely of law's pragmatism. The view here, by contrast, is that many of those features—consideration, duress, excuse doctrines—already had their basis in the conceptual ideas associated with contract-as-vow-or-oath. Thus, by having a more pluralistic conception of promise that admits these other distinctive types of institutions into promise's matrix, we can gain a greater understanding of the internal structure of contract.

¹²⁶ Hogg, supra note 7, at 45.

¹²⁷ Restatement (Second) of Contracts §90(2).

¹²⁸ See Edward Yorio & Steven Thel, The Promissory Basis of Section 90, 101 Yale L.J. 111 (1991).

¹²⁹ Some promissory theorists should have no truck with the core of Section 90 since it, after all, requires first and foremost a promise. There was, however, always a worry that “promissory estoppel”—as Section 90 had come to be called—was a bit of a “misnomer” because “reliance” would “come to dominate its ‘promissory’ aspect.” Michael B. Metzger & Michael J. Philips, The Emergence of Promissory Estoppel as an Independent Theory of Recovery, 35 Rutgers L. Rev. 472, 537 (1983). To be fair, that may never have quite come to pass. See, e.g., Alan Schwartz & Robert E. Scott, Precontractual Liability and Preliminary Agreements, 120 Harv. L. Rev. 661, 671 (2007).

¹³⁰ See In re Bashas’ Inc., 468 B.R. 381, 384 (D. Ariz. 2012) (“As of 2005, only two states, Iowa and New Jersey, appeared to have adopted subsection 2 of §90.”) (citing Evelyn Brody, The Charity in Bankruptcy and Ghosts of Donors Past, Present, and Future, 29 Seton Hall Legis. J. 471, 514 n.133 (2005); Farnsworth, E. Allan, Promises and Paternalism, 41 Wm. & Mary L. Rev. 385, 404–405 (2000)Google Scholar: “The exception for charitable subscriptions has played to mixed reviews.” For the Iowa and New Jersey cases adopting it, see Salsbury v. Northwestern Bell Telephone Co., 221 N.W.2d 609 (Iowa 1974); More Game Birds in America, Inc. v. Boettger, 14 A.2d 778 (N.J. 1940). For a famous case declining to follow §90(2), see King v. Trustees of Boston University, 647 N.E.2d 1196, 199 n.4 (Mass. 1995).

¹³¹ Fried reminds us that Contract as Promise “pours” “much scorn” on the doctrine of consideration. Fried, supra note 121, at 35.

¹³² See Ohio Rev. Code Ann. §3103.06 (2023).

¹³³ See In re Marriage of Cooper, 769 N.W.2d 582 (Iowa 2009).

¹³⁴ See Crofford v. Adachi, 150 Hawaii 518 (2022).

¹³⁵ See In re Marriage of Mehren & Dargan, 118 Cal.App. 4th 1167 (2004); Diosdado v. Diosdado, 97 Cal.App. 4th 470 (2002).

¹³⁶ See Reese v. Reese, 984 P.2d 987 (Utah 1999).

¹³⁷ See Laudig v. Laudig, 425 Pa. Super. 228 (1993).

¹³⁸ See Gilley v. Gilley, 778 S.W.2d 862 (Tenn. Ct. App. 1989).

¹³⁹ See Ansin v. Craven-Ansin, 457 Mass. 283 (2010).

¹⁴⁰ Hi. Rev. Stat. Ann. §572–522 (2019).

¹⁴¹ BT Gittin 52a–b. The Aramaic apotropus clearly comes from the Greek for “guardian.” Today we would probably use the word “fiduciary” here. The debate in the Talmud centers on whether the fiduciary needs to swear only when appointed by the father, only when appointed by the courts, or irrespective of appointment method. Israel's Supreme Court incorporated some of the Talmudic principles of fiduciary law in Muberman v. Segal, 32(iii) P.D. 85 (1978). For discussion, see 4 Menachem Elon, Jewish Law: History, Sources, Principles 1692, 1739, 1837, 1865–1866 (Bernard Auerbach & Melvin Sykes trans., 1994) (1988). For a more general treatment of Jewish law and fiduciary law (with plenty about oaths), see Chaim Saiman, Fiduciary Principles in Classic Jewish Law, in Oxford Handbook of Fiduciary Law 544 (Evan Criddle et al eds., 2019).

¹⁴² Consider in this regard that patent applications require an oath of invention. See 35 U.S.C. §115(b). The law could statutorily require oaths by fiduciaries that they intend to or are comporting themselves in accordance with their duties to pursue the best interests of their beneficiaries. This may give rise to issues about corporate oaths or oaths by AI serving in fiduciary roles, see, e.g., Anna Carnochan Comer, AI: Artificial Inventor or the Real Deal, 22 N. Car. J.L. & Tech. 447 (2021), but I will leave that wrinkle for another time. Thanks to Janet Freilich for some guidance on the patent oath.

¹⁴³ For a set of reflections on fiduciaries in private law, see generally Stephen R. Galoob & Ethan J. Leib, Motives and Fiduciary Loyalty, 65 Am. J. Juris. 41 (2020); Ethan J. Leib & Stephen R. Galoob, Fiduciary Political Theory: A Critique, 125 Yale L.J. 1820 (2016); Ethan J. Leib, Friends as Fiduciaries, 86 Wash. U. L. Rev. 665 (2009).

¹⁴⁴ For the argument that fiduciary duties are a species of contract duties, see Frank H. Easterbrook & Daniel R. Fischel, Contract and Fiduciary Duty, 38 J.L. & Econ. 425 (1993).

¹⁴⁵ See Kimel, supra note 7, at 96–99.

¹⁴⁶ See Jody S. Kraus, Personal Sovereignty and Normative Power Skepticism, 109 Colum. L. Rev. Sidebar 126 (2009).

¹⁴⁷ See Murphy, supra note 119, at 162; Liam Murphy, The Artificial Morality of Private Law: The Persistence of an Illusion, 70 Univ. Toronto L.J. 453, 458 (2020).

¹⁴⁸ See Fruh, supra note 12 (on vow and oaths); Brake, Elizabeth, Is Divorce Promise-Breaking?, 14 Ethical Theory & Moral Prac. 23–39 (2011)Google Scholar (on vows); Liberman, Alida, On the Rationality of Vow-making, 100 Pac. Phil. Q. 881 (2019)CrossRefGoogle Scholar (on vows); Liberman, Alida, For Better or for Worse: When are Uncertain Wedding Vows Permissible?, 47 Soc. Theory & Prac. 765 (2021) (on vows)Google Scholar; Scanlon, Thomas, Promises and Practices, 19 Phil. & Pub. Affs. 199, 223–226 (1990)Google Scholar (an appendix on oaths).