It’s more common among Thomists to hear condemnations of Ockhamism than appreciations of the fundamental problems that brought Ockham into conflict with the tradition that came before him. This is part of a larger problem that everyone is prone to treating the ideas of those who disagree with us as though they were not transmitted by rational persuasion. But ideas don’t spread by microbes, and even pointing to social or historical forces that dispose us to believing things only takes one so far since things like these are really just filters that allow us to see certain truths with greater ease but which make other truths harder to see.
The Ockhamist critique of other Scholastics frequently appeals to the logical consequences of believing in an omnipotent and perfectly free creator of the universe. Consider an argument like this, which, though more extreme than Ockham, does arise from Ockhamist considerations of omnipotence:
Given omnipotence, there is nothing about nature that could not be otherwise.
Certainty about nature requires that there be something about nature that could not be otherwise.
Given omnipotence, there is nothing certain about nature.
The upshot is that our study of nature is nothing but the collecting of facts (i.e. things that God happened to do, but which might just as well been different) and so the only truth one can have -whether in a supposed philosophy of nature or science of it – consists in gathering up propositions that one explicitly considers as able to be otherwise, and therefore as intrinsically uncertain. The modern idea of the truths of nature being perfectly equivalent to the facts about nature arises quite naturally from the belief that the universe is the free act of a being that could do whatever is logically possible.
These facts might arrange themselves in patterns, and repeated experience might yield no exceptions to the pattern, but for all that the facts does not become a necessary truth. It is amusing or at least paradoxical that laws of nature are treated as necessary or exceptionless when they might well have been first suggested by an epistemology that is an explicit response to the absence of necessity in nature, i.e. a view of nature that necessarily allows for anything logically possible to happen.