… is from page 226 of Thomas Sowell’s excellent 1987 volume, A Conflict of Visions (original emphasis):
Results matter – they are the ultimate justification of processes – but it is only the general effectiveness of particular processes (competitive markets, constitutional government) that can be gauged by man, not each individual result in isolation.
DBx: Indeed so. Isolated instances of success or of failure are never reliable evidence of the goodness or badness of any rule or policy.