The rise and fall of popular positions in the field of philosophy is not governed solely by reason. Philosophers are generally reasonable people but, as with the rest of the human species, their thoughts are heavily influenced by their social settings. Indeed, they are perhaps more influenced than thinkers in other fields, since popular or ‘big’ ideas in modern philosophy change more frequently than ideas in, say, chemistry or biology. Why?I'm not sure Studemeyer is correct in what he says about testability being the litmus test of science. Perhaps it should be, but it often isn't. For example, it's difficult to imagine how some of the hypotheses concerning the origin of life, macroevolution, the big bang, the multiverse, string theory, and so on, could be tested. Yet they're all considered by many scientists to be legitimate science. The notion of a "scientific method," despite the fact that it's in the early chapters of just about every secondary school textbook, is not one that many working scientists actually ascribe to.
The relative instability of philosophical positions is a result of how the discipline is practised. In philosophy, questions about methods and limitations are on the table in a way that they tend not to be in the physical sciences, for example. Scientists generally acknowledge a ‘gold standard’ for validity – the scientific method – and, for the most part, the way in which investigations are conducted is more or less settled.
Falsifiability rules the scientific disciplines: almost all scientists are in agreement that, if a hypothesis isn’t testable, then it isn’t scientific. There is no counterpoint of this in philosophy. Here, students and professors continue to ask: ‘Which questions can we ask?’ and ‘How can we ask, much less answer, those questions?’ There is no universally agreed-upon way in which to do philosophy.
Given that philosophy’s foundational questions and methods are still far from settled – they never will be – it’s natural that there is more flux, more volatility, in philosophy than in the physical sciences. [T]his volatility... is [similar to] changes of fashion.
When thinking about fashion in philosophy, there are four basic categories under which texts, thinkers and ideas can be grouped. By considering the interrelation of these groups, we can begin to glean how an idea becomes fashionable. The four categories are the fashionable, the foundational, the prohibited, and the unfashionable.
Scientists like their theories to be testable, but if they aren't they want them to be elegant, and if they aren't they want them to have expansive explanatory power, and if they don't they want them to at least conform to a materialist worldview, and if they're incompatible with materialism, well, then, they're not science.
In any event, the rest of the article is given to fleshing out Studemeyer's four categories. One of the best parts of the essay is a side-bar question, to which readers are invited to respond, which asks what philosophical ideas are fashionable today but won't be much longer. Some of the responses are very interesting although they're not all strictly philosophical.