 Few are outright skeptics, however. Many take a more ambiguous stance. Sören Häggqvist, for example, has developed a normative model for philosophical thought experiments (see Häggqvist 1996 and 2009). Surprisingly, none of the commonly accepted philosophical thought experiments satisfies his model. And the process of identifying successful thought experiments is only the first step in addressing the central epistemological challenge posed by thought experiments. It gets much messier once we begin to ask exactly how reliable “successful” thought experiments are. Granted, there is some justice in worrying about the reliability of philosophical thought experiments (see, e.g., Klee 2008). This might be true for ethics (see Dancy 1985, Jackson 1992; Wilson 2016), conceptual analysis (see Fodor 1964), and philosophy of mind: “A popular strategy in philosophy is to construct a certain sort of thought experiment I call intuition pump. […] Intuition pumps are often abused, though seldom deliberately” (Dennett 1985, p. 12). The claim by Dennett and others is that thought experiments too often rest on prejudice and faulty common sense; they are inherently conservative, while real science will likely result in highly-counterintuitive outcomes. Dennett believes that thought experiments rest on naive “folk concepts,” which is why they can be so misguided. It is far from clear that this is a fair charge. Everything involved in Galileo’s thought experiment that produced the principle of relativity could be called “folk concepts.” If we are inside a ship and perform a number of experiments, such as walking about, tossing a ball, watching birds fly about, we could not tell whether we are at rest in port or sailing over a smooth sea. The upshot is that nature behaves the same either way; the laws of nature are the same in any inertial frame. This result is profound and is still with us in Einstein’s relativity, whether it is folk physics or not.