Debugging an API, which may have obscure corner cases or usability quirks seems appropriate to me. "Debugging" an algorithm which has inherent logical flaws by

Debugging an API, which may have obscure corner cases or usability quirks seems appropriate to me. "Debugging" an algorithm which has inherent logical flaws by attempting to patch it up with case-base reasoning and exceptions (logical, not runtime) is a road to disasters. I have seen too many devs trying to hill-climb their way out of a logical hole and the result is invariably a mess of a program which is still wrong. Also, in case of concurrent and parallel code debugging is basically useless since realistic timing conditions are not reproduced. I personally prefer logging, which gives a faster and more targeted trace of program behaviour than step debugging.