The received theories of epistemology identify abductive inferences with the cognitive patterns of speculation (hypothesis formation) and insist that they cannot verify or confirm hypotheses. I criticize various descriptions of abduction, offer a structural analysis of abductive inference,, characterize abduction without alluding to its putative role in inquiry, and then demonstrate that some abductions do provide evidence and that not all scientific hypotheses derive from abductive inferences. This result challenges those notions of scientific k knowledge that dismiss some central scientific (...) ideas (for example, evolution) as ‘meta-physical research programs’ or ‘just theories’ when they are instead well substantiated by abductive evidence. (shrink)