Well, maybe you don't? Science gives you the tools to know when you're wrong. If you can't falsify your hypotheses then you're not generating new knowledge. So

Well, maybe you don't? Science gives you the tools to know when you're wrong. If you can't falsify your hypotheses then you're not generating new knowledge. So maybe stop trying and do something else. Which is not to say that we should stop psychological research- not at all. But maybe we should not treat psychology in the same way we treat science. Specifically, we shouldn't be trying to apply the scientific method in psychological research. Applying the tools of science in a domain where no scientific questions can be answered is only going to produce noise and confusion. I know that would really hurt psychologists' pride but, for example, philosophers are not considered scientists and yet their contributions to human knowledge are difficult to deny. Similar points have been made much more forcefully in "Cargo Cult Science", but I don't want to be mean myself. I'm just trying to say that I think there's far better ways to do psychology than trying to do it like it's physics or chemistry.