What is the reason behind explicitly stating the background knowledge K when discussing formal theories of confirmation?

Excluding the idea that the normal epistemologica practice always presupposes some known "data", is there a more specific reason why we talk of E confirming H relative to K, and not of simply E confirming H?

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    Because E does not confirm anything without K. If we measure temperature by a mercury thermometer to confirm that we have a fever, for example, we need to presuppose that mercury rises proportionally to the temperature, and that alone involves a lot of background knowledge about mercury, volume, pressure and the like. If the mercury column were to fall instead we would get a false negative.
    – Conifold
    Commented May 12, 2021 at 11:04

1 Answer 1


This was hinted in Hempel's discussion of the Raven Paradox as referenced here:

Hempel (1945), who discussed these cases of the ravens, concluded that non-black non-ravens (as well as any other object that is not a raven or black) can indeed be used to confirm the ravens hypothesis. He attributed the paradoxical character of this alleged paradox to the psychological fact that we assume there to be far more non-black objects than ravens. However, the notion of confirmation he was explicating was supposed to presuppose no background knowledge whatsoever. An example by Good (1967) shows that such an unrelativized notion of confirmation is not useful (see Hempel 1967, Good 1968).

So if there's no background knowledge assumed for most empirical Bayesian like reasoning, Raven paradox does strangely suggest anytime we see non-ravens or non-black things counts as a confirmation of the empirical argument that all ravens are black which is undesirable...

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