> If there's no alternative it means the hypothesis is not falsifiable, right? Well, not really. For example, we don't understand how some brain function works

> If there's no alternative it means the hypothesis is not falsifiable, right? Well, not really. For example, we don't understand how some brain function works. For some reason we might get a hypothesis that it is governed by a production of a certain neurotransmitter (very simplified here). At that time we have no other version of how the function might work at all. Then we do experiments where we mess with the said neurotransmitter, or a brain region, etc. If the results show that there is no measurable effect on the brain function, then that hypothesis becomes disproven (or at least a certain specific way of understanding that hypothesis). If there is no alternative that might just mean that we haven't found it yet. Or that the current framework we're using is not suitable to the question. But even then working on existing hypothesis might give a lot of information on what framework might actually work.