The scientific method involves having an idea, testing the idea, and modifying the idea to fit the evidence.
It assumes that human reason is all that humans require to understand the universe and is often used in science, but not in all sciences. It's relatively easy to use in chemistry and physics, but harder to use in biology.
Comically, social scientists attempt to use the scientific method and would like to think that they succeed. Nevertheless, I know many a physicist or chemist that believes that sociologists, psychologists, economists, etc... are not scientists and aren't even trying to use the scientific method.
Personally, I suspect that the scientific method is more useful for certain areas of study than others.