When I was a grad student in psychology, I audited a 20th century philosophy of science course. I did my best to absorb all the great discussions, but one remark the professor made continues to bother me because I've never been able to make sense of it: She said that a belief that science is continually (if asymptotically) improving does not necessarily mean that there is a true state of affairs that is being approximated. Yet, my understanding of fallibilism is that in order for a theory to be more or less accurate, there must be some criterion against which the theory is compared to determine its accuracy -- thus, fallibilism appears to carry an ontological commitment that some state of affairs actually is the case, even if we will never apprehend it perfectly.
The only way I've been able to make any sense of my professor's claim is to understand it as rejecting the premise that the world can ever be described as a "state of affairs" -- in other words, that the world our theories seek to describe is in constant flux (hat tip to Heraclitus). But I don't find this explanation very satisfying.