First evidence: rules exist. Ordinary grammar books talk about the error of faulty or vague pronoun reference, and specify a rule like “A pronoun should refer back to a single unmistakable antecedent noun.” To be sure, it is difficult to give a criterion or an algorithm for “unmistakable,” but as I said earlier, human readers clearly have the ability to keep track of which individual is which, without making mistakes, also human writers have the ability to enable this by clearly expressing their meaning. When mistakes occur, this is the fault of the writer, not the reader. Humans would not make rules if humans were unable to apply them.
Second, the difficulty that computers have with some exception cases is not that there is no rule, but rather that the rule requires knowledge of human affairs and customs. For example:
Gen 4:20 Adah gave birth to Jabal; he was the father of those who live in tents and raise livestock.
Gen 4:26 Seth also had a son, and he named him Enosh.9
Gen 12:18 So Pharaoh summoned Abram. “What have you done to me?” he said.
The first example requires knowledge that “Adah” is the name of a woman, not a man, which is provided in 4:19 (“Lamech married two women, one named Adah and the other Zillah”). This knowledge could be given to the computer through a list of all proper names classified by gender, but in any case, there is a further clue given by “gave birth to.” The computer would have to understand that only women can give birth. There is another difficulty: the verse could easily have been written “Lamech had a son, Jabal; he was the father of those who live in tents and raise livestock,” with no clue given by pronoun gender. To understand why “he” still refers back to “Jabal,” we would have to understand the purpose of 4:19–22, which is to tell us which occupations the descendants Lameth followed. Jabal was the ancestor of tent dwellers, Jubal of musicians, Tubal Cain of blacksmiths. This, in Chastain’s words, is a convention “relevant to the genre.”
Gen 4:26 is an example of a double pronoun use: “he named him Enosh.” The assumption is that the verb is not reflexive, otherwise the reflexive pronoun “himself” would have been used.10 We also know that human biology generally precludes children naming their parents. Gen 12:18 requires understanding of speech conventions. If “he” refers to Pharoah, and Pharoah uttered “What have you done to me?,” then “you” refers to Abram and “me” to Pharaoh. To understand that “he” refers to Pharoah, we have to understand what Abram is doing, which is explained by 12:17. God is inflicting plagues because Pharaoh has taken Sarai, Abram’s wife.
Third, the knowledge required is likely to be timeless and universal (or at least relatively stable over time, and across languages). We can generally understand texts written in ancient languages and by authors from very different cultures. Mark wrote, “Herod feared John, knowing that he was a just man” with the intention that “he” (αὐτὸν) should refer back to “John.” His intention was realized even though he wrote in Greek, and his English translators have followed him by using the appropriate English pronoun, as do Latin translators (“Herodes enim metuebat Iohannem sciens eum virum iustum”), French (“Hérode craignait Jean, le connaissant pour un homme juste”), German (“Herodes aber fürchtete Johannes; denn er wußte, daß er ein frommer und heiliger Mann war”), and so on. They are able to translate the reference because they understand the rules of the language they were translating into, and Mark would have understood the rules of the original Greek in exactly the same way. Imagine he was working from some lost text in Aramaic, which used the same pronominal reference, or that he had some mental sentence which he wanted to translate into Greek. Thus, the rules cannot be arbitrary if the knowledge required to apply them is knowledge of human nature itself, including the nature that drives people to construct such stories.
Fourth, the cases where resolution is impossible are where no appropriate rule exists.
On the way, at a place where they spent the night, the LORD met him1 and tried to kill him2. But Zipporah took a flint and cut off her son’s foreskin, and touched his3 feet with it, and said, “Truly you are a bridegroom of blood to me!” So he4 let him5 alone. [Exodus 4:24-26]11
Rabbinical interpreters have offered a wide range of meanings for this text.12 The first “him” could refer to Moses, or to his son, either of whom has been struck down by some illness caused by God. The second clearly co-refers with the first. But whether “his feet” refers to Moses’ feet, his son’s feet or God’s feet, is difficult to say. As for the fourth and fifth, logic suggests that the subjects are different, and also that the fifth “he” co-refers with the first and second (the attempt on his life is dropped). But whether it is Moses or his son is not clear. One translation has “it” for the fourth pronoun, meaning the illness that struck down Moses (or his son). The text is most likely corrupt, but that confirms the point that no appropriate rule exists.
Of course, a complete theory governing pronoun resolution is likely to be complex and difficult, and is a problem for computational linguistics, but it is not my purpose to offer a precise theory of co-reference resolution, or any general theory of how people signify and understand co-reference. My assumption is such a theory must be possible. There have to be certain well understood rules of communication, which allow both authors and translators to communicate reference by written or spoken signs, in whatever language they choose.
Proper Names
While pronoun resolution is difficult, proper names and definite descriptions are somewhat easier. For proper names, the rule is that tokens of the same name always co-refer, except when they have been disambiguated in some way. If there are two or more people called “Mary,” the rule is that the name should be further qualified by means of a patronymic or description. For example, Mary Magdalene is qualified as Magdalene, as is Mary the mother of James and Joseph, who is also called the other Mary (Matthew 27:61, 28:1).13 Likewise, where the reader might think that different individuals had the same name, or where it is not clear, a description may be added. Thus, John 11:2 states, “It was that Mary [the sister of Martha] who anointed the Lord with ointment,” in case we think she is a different Mary, although Luke does not say whether they are the same or different. Likewise, Acts 13:14 tells us that the Apostles came to Antioch in Pisidia, to distinguish it from the Antioch in Syria.
The ambiguity can also be resolved by the passage of time. There are two people called “Herod” in the gospels. The first, the infant boy slayer of Matthew 2, was Herod the Great (74 BC – 4 BC), whereas the person to whom Jesus was sent before his crucifixion (and the one who had John the Baptist murdered) was Herod the Great’s son Herod Antipas (Matthew 14:1; Luke 3:1). There is no overt disambiguation in Luke. Luke 1:5 says, “In the time of Herod king of Judea,” and Luke 3:1 says, “In the fifteenth year of the reign of Tiberius Caesar—when Pontius Pilate was governor of Judea, Herod tetrarch of Galilee.” However, the infant killing episode took place at Jesus’ birth, whereas Luke 3 explicitly states that Jesus was about thirty.
The convention that non-disambiguated tokens of the same name co-refer gives rise to the following puzzle, Quran 3:33-35:
3:33 Indeed, Allah chose Adam and Noah and the family of Abraham and the family of Imran over the worlds—
3:34 Descendants, some