Falsifiability

That is because if it cannot be falsified, then it means nothing for it to be true. If a proposition is unfalsifiable, then there is no difference between a universe in which it is true and a universe in which it is not true.

You give more credence to falsifiability, arrived logically via modus tollens (U --> ^O. where U = universal statement and O = observation; If O; Thus ^U, than I do in demarking between science and non or pseudo-science, or, as you say, "a universe in which it is true and a universe in which it is not true." First, the principle of falsifiability is just that-- a principle which cannot in itself be falsified as is also true with the logical positivist's verifiability principle. Secondly, the rejection of a hypnotheis due to an example of falsifiability can itself be irrational, as in the 1925 Michelson-Morely experiment relative to Einstein's Theory of Relativity. (This concept can only be challenged when applied to other theories. You might be hard pressed to falsify the Theory of Natural Selection, for example.) Thirdly, as the article also points out, there is the problem of perceived as opposed to real verifiability-- gets to the crux of what we really mean by "true" as used in your sentence.

http://physicsworld.com/cws/article/print/16478

Finally, as I stated earlier, Popper's view is that there can be no inference that given the lack of falsifiability, a theory is false, meaningless, or trivial-- only that it cannot be tested. "I thus felt that if a theory is found to be non-scientific, or "metaphysical" (as we might say), it is not thereby found to be unimportant, or insignificant, or "meaningless," or "nonsensical." But it cannot claim to be backed by empirical evidence in the scientific sense—although it may easily be, in some genetic sense, the "result of observation.""

http://karws.gso.uri.edu/JFK/critical_thinking/Science_pseudo_falsifiability.html