First, some caveats. This is really a discussion of oath-taking as it existed (and exists) around the Mediterranean and Europe. My understanding is that the basic principles are broadly cross-cultural, but I can’t claim the expertise in practices south of the Sahara or East of the Indus to make that claim with full confidence. I am mostly going to stick to what I know best: Greece, Rome and the European Middle Ages. Oath-taking in the pre-Islamic Near East seems to follow the same set of rules (note Bachvarova’s and Connolly’s articles in Horkos), but that is beyond my expertise, as is the Middle East post-Hijra.
Second, I should note that I’m drawing my definition of an oath from Alan Sommerstein’s excellent introduction in Horkos: The Oath in Greek Society (2007), edited by A. Sommerstein and J. Fletcher – one of the real “go-to” works on oath-taking in the ancient Mediterranean world. As I go, I’ll also use some medieval examples to hopefully convince you that the same basic principles apply to medieval oaths, especially the all-important oaths of fealty and homage.
(Pedantry note: now you may be saying, “wait, an introduction? Why use that?” As of when I last checked, there is no monograph (single author, single topic) treatment of oaths. Rather, Alan Sommerstein has co-authored a set of edited collections – Horkos (2007, with J. Fletcher), Oath and State (2013, with A. Bayliss) and Oaths and Swearing (2014, with I. Torrance). This can make Greek oaths a difficult topic to get a basic overview of, as opposed to a laundry list of the 101 ancient works you must read for examples. Discussions of Roman oaths are, if anything, even less welcoming to the beginner, because they intersect with the study of Roman law. I think the expectation has always been that the serious student of the classics would have read so many oaths in the process of learning Latin and Greek to develop a sort of instinct for the cultural institution. Nevertheless, Sommerstein’s introduction in Horkos presents my preferred definition of the structure of an oath.)
Alright – all of the quibbling out of the way: onward!
So what is an Oath? Is it the same as a Vow?
Ok, let’s start with definitions. In modern English, we often use oath and vow interchangeably, but they are not (usually) the same thing. Divine beings figure in both kinds of promises, but in different ways. In a vow, the god or gods in question are the recipients of the promise: you vow something to God (or a god). By contrast, an oath is made typically to a person and the role of the divine being in the whole affair is a bit more complex.
(Etymology digression: the word “oath” comes to us by way of Old English āþ (pronounced “ath” with a long ‘a’) and has close cousins in Dutch “Eed” and German “Eid”. The word vow comes from Latin (via Middle English, via French), from the word votum. A votum is specifically a gift to a god in exchange for some favor – the gift can be in the present tense or something promised in the future. By contrast, the Latin word for oath is ius (it has a few meanings) and to swear an oath is the verb iuro (thus the legal phrase “ius iurandum” – literally “the oath to be sworn”). This Latin distinction is preserved into the English usage, where “vow” retains its Latin meaning, and the word “oath” usurps the place of Latin ius (along with other words for specific kinds of oaths in Latin, e.g. sacramentum)).
In a vow, the participant promises something – either in the present or the future – to a god, typically in exchange for something. This is why we talk of an oath of fealty or homage (promises made to a human), but a monk’s vows. When a monk promises obedience, chastity and poverty, he is offering these things to God in exchange for grace, rather than to any mortal person. Those vows are not to the community (though it may be present), but to God (e.g. Benedict in his Rule notes that the vow “is done in the presence of God and his saints to impress on the novice that if he ever acts otherwise, he will surely be condemned by the one he mocks“. (RB 58.18)). Note that a physical thing given in a vow is called a votive (from that Latin root).
(More digressions: Why do we say “marriage vows” in English? Isn’t this a promise to another human being? I suspect this usage – functionally a “frozen” phrase – derives from the assumption that the vows are, in fact, not a promise to your better half, but to God to maintain. After all, the Latin Church held – and the Catholic Church still holds – that a marriage cannot be dissolved by the consent of both parties (unlike oaths, from which a person may be released with the consent of the recipient). The act of divine ratification makes God a party to the marriage, and thus the promise is to him. Thus a vow, and not an oath.)
So again, a vow is a promise to a divinity or other higher power (you can make vows to heroes and saints, for instance), whereas an oath is a promise to another human, which is somehow enforced, witnessed or guaranteed by that higher power.
An example of this important distinction being handled in a very awkward manner is the “oath” of the Night’s Watch in Game of Thrones (delivered in S1E7, but taken, short a few words, verbatim from the books). The recruits call out to … someone … (they never name who, which as we’ll see, is a problem) to “hear my words and bear witness to my vow”. Except it’s not clear to me that this is a vow, so much as an oath. The supernatural being you are vowing something to does not bear witness because they are the primary participant – they don’t witness the gift, they receive it.
I strongly suspect that Martin is riffing off of here are the religious military orders of the Middle Ages (who did frequently take vows), but if this is a vow, it raises serious questions. It is absolutely possible to vow a certain future behavior – to essentially make yourself the gift – but who are they vowing to? The tree? It may well be “the Old Gods” who are supposed to be both nameless and numerous (this is, forgive me, not how ancient paganism worked – am I going to have to write that post too?) and who witness things (such as the Pact, itself definitely an oath, through the trees), but if so, surely you would want to specify that. Societies that do votives – especially when there are many gods – are often quite concerned that gifts might go awry. You want to be very specific as to who, exactly, you are vowing something to.
This is all the more important given that (as in the books) the Night’s Watch oath may be sworn in a sept as well as to a Weirwood tree. It wouldn’t do to vow yourself to the wrong gods! More importantly, the interchangeability of the gods in question points very strongly to this being an oath. Gods tend to be very particular about the votives they will receive; one can imagine saying “swear by whatever gods you have here” but not “vow yourself to whatever gods you have here”. Who is to say the local gods take such gifts?
Moreover, while they pledge their lives, they aren’t receiving anything in return. Here I think the problem may be that we are so used to the theologically obvious request of Christian vows (salvation and the life after death) that it doesn’t occur to us that you would need to specify what you get for a vow. But the Old Gods don’t seem to be in a position to offer salvation. Votives to gods in polytheistic systems almost always follow the do ut des system (lit. “I give, that you might give”). Things are not offered just for the heck of it – something is sought in return. And if you want that thing, you need to say it. Jupiter is not going to try to figure it out on his own. If you are asking the Old Gods to protect you, or the wall, or mankind, you need to ask.
(Pliny the Elder puts it neatly declaring, “of course, either to sacrifice without prayer or to consult the gods without sacrifice is useless” (Nat. Hist. 28.3). Prayer here (Latin: precatio) really means “asking for something” – as in the sense of “I pray thee (or ‘prithee’) tell me what happened?” And to be clear, the connection of Christian religious practice to the do ut des formula of pre-Christian paganism is a complex theological question better addressed to a theologian or church historian.)
The scene makes more sense as an oath – the oath-takers are swearing to the rest of the Night’s Watch to keep these promises, with the Weirwood Trees (and through them, the Old Gods – although again, they should specify) acting as witnesses. As a vow, too much is up in the air and the idea that a military order would permit its members to vow themselves to this or that god at random is nonsense. For a vow, the recipient – the god – is paramount.
Bret Devereaux, “Collections: Oaths! How do they Work?”, A Collection of Unmitigated Pedantry, 2019-06-28.