Isn't Popper's epistemology a form of Argument from Ignorance? "We assume it is true if it has not (yet) been falsified."
But the fact that it hasn't been falsified doesn't make it true; assuming that would be an Argument from Ignorance.
In other words: to what extent is Popper's reasoning valid in the context of the Argument from Ignorance and why?
Stephen Thornton describes Popper's position on scientific theories as follows:
As such it [a scientific theory] can be tested and falsified, but never logically verified. Thus Popper stresses that it should not be inferred from the fact that a theory has withstood the most rigorous testing, for however long a period of time, that it has been verified; rather we should recognise that such a theory has received a high measure of corroboration. and may be provisionally retained as the best available theory until it is finally falsified (if indeed it is ever falsified), and/or is superseded by a better theory.
This suggests that scientific theories never reach the status of being verified, let alone true. What one can do with such theories, however, is falsify them.
Douglas Walton describes an argument from ignorance as follows: (page 3)
[David] Kelley ([The art of reasoning,] 148) describes this type of argument as having the form below, where A is a proposition, and the symbol ¬ stands for the negation of A.
¬A has not been proven true.
Therefore, A is true.
This is different from Popper's view of a scientific theory. Popper's scientific theory is never true. The burden of proof remains with those proposing the scientific theory. They, not those opposed to the theory, have the burden to try to falsify the theory.
Consider the question:
In other words: to what extent is Popper's reasoning valid in the context of the Argument from Ignorance and why?
Unlike the argument from ignorance, Popper's theory does not claim that a scientific theory is true, that is, verified. Because of that Popper does not need to rely on an argument from ignorance to verify a scientific theory since a scientific theory is at best corroborated, not verified. The main scientific activity is to look for ways to falsify, not verify, a scientific theory.
Reference
Thornton, Stephen, "Karl Popper", The Stanford Encyclopedia of Philosophy (Fall 2018 Edition), Edward N. Zalta (ed.), URL = https://plato.stanford.edu/archives/fall2018/entries/popper/.
Walton, Douglas, Arguments from Ignorance, The Pennsylvania State University Press, 1996.
Popper doesn't argue that we should believe something is true simply because it hasn't been falsified. He argues that we cannot assume it is false unless it has been, and that if it cannot be falsified in principle then it is not a scientific idea.
A difficulty that arises is that a proposition about the world that is true will not be falsifiable. So as we move into philosophy Poppers thoughts have to modified somewhat, and it seems likely this may also the case for certain propositions in physics.
He is not arguing from ignorance but, rather, arguing that decisions should not be taken on the basis of it. Innocent until proven guilty is the idea.
