The Footnote

The footnote occupies two lines at the bottom of page four hundred and six, and it does what footnotes are supposed to do: it records an inconvenience. Halloran had found three samples that did not behave as the rest did, could not account for them, and said so, in a sentence that took him, by his own account, longer to write than the chapter above it.

The temptation to omit them must have been considerable. They weakened nothing in his argument, which did not depend on them, and they invited exactly the sort of objection that a reader looking for a weakness would seize on. He recorded them anyway, together with the observation that he could offer no explanation and did not wish to invent one.

For twenty-eight years nobody made anything of it. The book was read, cited and eventually superseded in the ordinary way, and the footnote was carried forward into the second edition unchanged, which suggests that Halloran had not stopped thinking about it either.

What Fitzgerald noticed, in a reading undertaken for entirely unrelated reasons, was that the three anomalies shared a feature that could not have been visible in Halloran's time and was trivially visible in hers. The apparatus that would have shown it did not exist when he wrote.

The paper she published is, in substance, a demonstration that the exceptions were not exceptions at all but the clearest instances of a mechanism that the main argument had described imprecisely. It is dedicated to Halloran, who was by then dead, and it quotes the footnote in full on its first page.

The moral usually drawn from this is that anomalies should be published, and that is true as far as it goes. The sharper point is one that Fitzgerald herself makes in her introduction and that is easier to state than to act on: the footnote was useful precisely because Halloran refused to explain it.

An explanation, even a tentative one, would have given the next reader something to accept or reject, and the overwhelming likelihood is that it would have been accepted, filed and forgotten. What he left instead was an unresolved fact, which is a far more durable object, and which sat in the literature for three decades waiting for an instrument to be invented.