Some valid empirical questions are not testable in the Popperian sense. Theories of evolution are not, for example, at least in any useful way. Instead, a model based conception of science is required.
> Some valid empirical questions are not testable in the Popperian sense.
If by "valid" you mean "scientific", no, not true. As long as such questions cannot be tested and potentially falsified, they aren't science.
> Instead, a model based conception of science is required.
Einstein had a model for General Relativity in 1915, but the scientific world reserved judgment until it could be tested and potentially falsified. In 1919 an opportunity for a falsifiable test appeared -- an eclipse of the sun that would show the effect of space-time curvature and either validate or falsify Einstein's theory. (https://eclipse2017.nasa.gov/testing-general-relativity)
Einstein's model was interesting, but until a falsifiable test could be carried out, it was philosophical speculation. This is how science works.
I've been having this same conversation for decades -- psychologists want the status of science without the discipline of science. But that would require science to be redefined, which would dismantle the Enlightenment. Not happening.
