Physicists can have opinions and beliefs about the theories. But physics as a subject cannot accommodate opinions. So the history of science, as you have said, may appear to be a history of opinions and beliefs of the scientists.

The basic difference in the field of physics is the entry of QM. Before that, a question 'What is an electron?' will give you a single answer: it is a particle, which may show some wave nature (the answer is provisional in the sense that it cannot explain why it shows the wave nature). But Heisenberg, Schrodinger and the rest suggested that an electron has dual existence: it exists as a wave and particle at the same time, like the Schrodinger's cat, it is alive and dead at the same time. Thus there are two answers: it is a particle and it is wave. Thus, they gave a metaphysical explanation to a physical problem.

So to answer the question 'In this particular situation, will it be a particle or a wave?' you have to depend on probability, and this gave rise to QM.