[general_re]

Indeed, but in the context of science, a theory has value precisely because it can be falsified, according to Popper...

Very true, but that doesn't mean that when you are presented with two falsifiable theories, one of them must therefore be true, which is essentially what was claimed by the original sentence I quoted:

According to Sir Karl Popper, when given two theories an experiment will decide one true and one false.

But, of course, both theories could be false, at the very least. Consider two theories about where babies come from - A) the stork brings them, or; B) from the cabbage patch. Since both of these are essentially falsifiable, and given the reasoning above, we should be able to conceive of an experiment that will prove one of these theories to be true ;)

[Alamo-Girl]

Aha! Great catch! Thank you, general_re! I'll reword that sentence. How about something like this?:

According to Sir Karl Popper, competing theories that are equally falsifiable ought to result in one or the other being true; when the competing theories are both true as in wave/particle duality, the undecidability itself must be accepted as an axiom.