The question that has appeared this year is "What questions (plural) have disappeared and why?" Countless questions have disappeared, of course, but for relatively few reasons.
The most obvious vanishings are connected to the passing of time. No one asks anymore "Who's pitching tomorrow for the Brooklyn Dodgers?" or "Who is Princess Diana dating now?"
Other disappearances are related to the advance of science and mathematics. People no longer seriously inquire whether Jupiter has moons, whether DNA has two or three helical strands, or whether there might be integers a, b, and c such that a^3 + b^3 = c^3.
Still other vanished queries are the result of changes in our ontology, scientific or otherwise. We've stopped wondering, "What happened to the phlogiston?" or "How many witches live in this valley?"
The most interesting lacunae in the erotetic landscape, however, derive from lapsed assumptions, untenable distinctions, incommensurable mindsets, or superannuated worldviews that in one way or another engender questions that are senseless or, at least, much less compelling than formerly. "What are the election's exact vote totals" comes to mind.
Now that I've clarified to myself the meaning of "What questions have disappeared and why?" I have to confess that I don't have any particularly telling examples. (Reminds me of the joke about the farmer endlessly elucidating the lost tourist's query about the correct road to some hamlet before admitting, "Don't reckon that I know.")
JOHN ALLEN PAULOS, bestselling author, mathematician, and public speaker is professor of mathematics at Temple University in Philadelphia. In addition to being the author of a number of scholarly papers on mathematical logic, probability, and the philosophy of science, Dr. Paulos books include Innumeracy - Mathematical Illiteracy and Its Consequences, A Mathematician Reads the Newspaper, and Once Upon a Number.