
all this behavior can be more or less plausibly explained as the effects of some humdrum combination of "instinct" or tropism and conditioned response. It is the novel bits of behavior, the acts that couldn't plausibly be accounted for in terms of prior conditioning or training or habit, that speak eloquently of intelligence; but if their very novelty and unrepeatability make them anecdotal and hence inadmissible evidence, how can one proceed to develop the cognitive case for the intelligence of one's target species?
Source: The Intentional Stance (1987), p. 250