The practice of physiognomy, as well as that of phrenology, have been summarily discredited by modern scientific research. as it turns out, the bumps on a person's head and one's facial characteristics give virtually no information about their personality characteristics. this is an important reminder of the importance of the critical thinking principle of

I believe the answer is: falsifiability.

Principle of falsifiability refers to the principle that stated a scientific theory is couldn't be formed if the accumulation of observational evidence is not possible. Because if something couldn't be tested through empirical methods, it could only be considered as hypothetical statement rather than a scientific theory.

The used coins.. .