But that these are the truth conditions for evidential support relations does not mean that only tautologies can be evidence, nor that only sets of tautologies can be one's background. If you prefer, this is supposed to be a 'test' for checking if particular bits of information are evidence for something else. So I agree that backgrounds in minds is one of the things we got to be interested in, as long as we want to say something about rationality. I just don't think that the usefulness of the test (the new truth-conditions) is killed. =]