If I take a single glance at a speckled hen, I know that I’ve seen many speckles, but I can’t say how many I’ve seen. I have immediate experience of a determinate fact, but the experience doesn’t provide certain knowledge of the fact.

“[O]ur difficulty is not that there must be characteristics of the many-speckled datum which pass unnoticed,” writes philosopher Roderick Chisholm. “[I]t is, more seriously, the fact that we are unable to make a reliable judgment about what we do notice.”

“The problem is significant, since every possible solution appears to involve serious consequences for the theory of empirical knowledge.”

(Roderick Chisholm, “The Problem of the Speckled Hen,” Mind 51:204 [October 1942], 368-373.)