Literary critic Adam Kirsch is reading a page of Talmud a day, along with Jews around the world.One of the most famous pieces of Jewish liturgy is Kol Nidre, which is recited every year on the eve of Yom Kippur. Its fame comes partly from its melody, which has appealed to even non-Jewish composers like Max Bruch, and partly from its substance. The phrase kol nidre means “all vows,” and the recitation is a legal formula for nullifying all the vows that one will make over the coming year. The idea that Kol Nidre exempts Jews from keeping their promises—so that no promise by a Jew can be relied on—was for centuries a staple of anti-Jewish polemic. But it is obvious that no society, much less one as law-bound as Talmudic Judaism, could survive if obligations could be so easily escaped. Modern commentaries on the Kol Nidre usually take pains to clarify that the vows or nedarim at issue are not promises to human beings, but religious oaths addressed to God, usually in the form of a vow not to do something in particular. The Nazirite vow, for instance, obligates the taker to abstain from wine and from cutting his or her hair for a period of at least 30 days. Other kinds of vows might involve sacrificing a piece of property to God, or swearing not to have anything to do with a particular person.The very existence of Kol Nidre suggests that the rabbis did not look very favorably on the practice of vowing. The Bible insists that a vow, once taken, must be kept: “When a man takes a vow to the Lord, or swears an oath to bind his soul with a bond, he shall not profane his word; he shall do according to all that proceeds out of his mouth,” says Numbers 30:2. But Jewish law recognizes that such vows are often made hastily, out of momentary passions like anger, and without full understanding of their consequences. Indeed, the most famous vow in the Bible is the one Jephthah takes in the Book of Judges, when he promises to sacrifice the first creature he sees on his return home from battle. This turns out to be his daughter, whom he duly kills, since he can’t go back on his word. The tale is practically a fable about the perils of vowing and leaves no doubt that the practice, though common, was never seen by Judaism as particularly admirable.One problem with the Bible’s treatment of vows is that it is so brief and general. “When a man takes a vow,” the Bible says—but what does it mean to take a vow? Is there a particular formula for vowing, or does any statement of intent serve the purpose? What if a person’s vow is ambiguously stated, so that it’s not clear exactly what he was vowing? These are just the kind of pragmatic questions that the Talmud is designed to answer, bridging the gap between biblical terseness and the needs of a functioning Jewish legal system.Tractate Nedarim, which Daf Yomi readers began this week, starts out by clarifying just what a vow should sound like. The Talmud never begins a subject at what seems like its logical beginning—it does not explain what a vow is, or why people might want to take them. Rather, the mishna on Nedarim 2a makes a statement about the form of a vow: “All substitutes of vows are like vows.” By “substitutes,” it means linguistic variants, some of which will be listed later in the Tractate. For instance, instead of saying that some item will be treated like a korban, a Temple sacrifice, you might use the word konam, but the effect is the same.This seemingly minor point actually goes to the heart of one of the Talmud’s most important ongoing investigations: To what extent does intention matter in Jewish ritual? Judaism is a religion of laws, many of which prescribe or forbid specific actions. But does the action itself matter, or is the law concerned with the motivation behind it? This question has already arisen in many different forms over the last three years of Daf Yomi reading. On Shabbat, for instance, objects are muktzeh, “set aside,” if they are not the kind of thing that would typically be used on that day. But can you render them usable if you intend in advance to use them? On Rosh Hashanah, a Jew is obligated to hear the shofar blown. But does it count if you are just walking on the street near a synagogue and happen to overhear the sound, or must you actually intend to fulfill the obligation?The same basic issue of intent is at the bottom of the discussion of vows. Is a vow a certain verbal formula, or are the words just the embodiment of an intention, which is what really matters? By saying that “all substitutes of vows are like vows,” the mishna seems to hold that intention is key: Any words that convey the intention to vow constitute an effective vow. But no sooner is this point established than the rabbis begin to worry about its ambiguities. Take the case of “one who says to another: I am avowed from you,” and then says, “That which I eat of yours.” It seems as if he is taking a vow not to eat any food that belongs to the person against whom the vow is taken. (This is precisely the kind of punitive vow that one might make in anger and then regret.) But the vower in this case never actually said, “I vow not to eat your food”; he simply said, “I am taking a vow against you,” and then mentioned food separately. Is this enough to make the vow valid?According to the mishna, it is: In such a case, the vower must not eat the food of the person he vowed against. However, in the Gemara we learn than Rabbi Shmuel disagreed: “The vow does not take effect until he says, I am avowed from you with regard to that which I eat of yours.” In other words, Shmuel demands that a vow be complete and explicit; being able to deduce its meaning is not enough. One reason for this is that the scope of an ambiguous vow is hard to determine. As Shmuel goes on to say, if I say to you, “I am avowed from you with regard to that which I eat of yours,” it is clear that the vow is binding only on me. I may not eat your food, but there is nothing to stop you from eating my food. If, on the other hand, I say simply, “I am avowed from you,” then the vow works both ways: Each person is forbidden to derive any benefit from the other. Rabbi Yosei, however, introduces a still finer distinction: “I am avowed to you” means we are both prohibited to each other, but “I am avowed from you” is only binding on me. As always in legal formulas, the smallest preposition might turn out to be crucial.Shmuel follows Rabbi Yehuda, who “holds that ambiguous intimations are not intimations.” If the meaning of a vow is not clear, it is not a real vow. The rabbis, however, take a more lenient view, saying that ambiguous intimations are allowed as long as their meaning can be discerned. In the subsequent pages of Gemara, the rabbis go on to test this principle against various different kinds of legal declarations. In a bill of divorce, for instance, is it enough for a man to write to his wife, “You are hereby permitted to marry any man,” or must he specifically say, “And this shall be to you from me a document of divorce”? The rabbis say the former is enough, since it is obvious that the “you” implied here is the man’s wife; after all, “a man does not divorce the wife of his fellow.” But the stricter standard of Yehuda requires the latter phrase as well, since “we require obvious intimations,” spelling out that this is a divorce. The rabbis extend the debate to include legally meaningful declarations like betrothal and gifts to charity. Long before the term became fashionable in 20th-century Anglo-American philosophy, the Talmud was alert to the idea of “speech acts”—words that themselves constitute deeds. It is because these speech acts were so powerful that the rabbis insisted on defining them so rigorously.***To read Tablet’s complete archive of Daf Yomi Talmud study, click here.Adam Kirsch is a poet and literary critic, whose books include The People and the Books: 18 Classics of Jewish Literature.