Comment 2 by Cartomancer :

The absence of any evidence for a phenomenon IS evidence for the absence of the phenomenon in cases where we would very much EXPECT there to be evidence for said phenomenon. It may not be absolute disproof of the phenomenon, but absolute disproof is really only the preserve of pure mathematicians and logicians anyway.

Indeed. The adage is perhaps useful in limited contexts. On a technicality, it seems to protect the deist god (the one who bears an uncanny resemblance to no god) from logical disproof. But this is (or should be) small comfort to the theists – whose object of worship has very specific attributes.

Against the claim that a polar bear lives in my basement, absence of any evidence to that effect is evidence of absence. Likewise, the non-existence of divine intercession legitimately represents negative evidence for the Biblical god.