 While Lewis allows that individual reports need not be very credible considered in isolation for coherence to have a positive effect, he is firmly committed to the view that their credibility must not be nil. He writes, in his discussion of reports from memory, that “[i]f … there were no initial presumption attaching to the mnemically presented … then no extent of congruity with other such items would give rise to any eventual credibility” (357). In other words, if the beliefs in a set have no initial credibility, then no justification will ensue from observing the coherence of that set. Thus, Lewis is advocating weak foundationalism rather than a pure coherence theory.