 What we term the “intuition–based account” of thought experiments comes in a naturalistic version (see Brendel 2004; Gendler 2007), and in a Platonic version (see Brown 1991a [2011]). We begin with a discussion of the latter. Brown holds that in a few special cases we do go well beyond the old empirical data to acquire a priori knowledge of nature (see also Koyré 1968). Galileo showed that all bodies fall at the same speed with a brilliant thought experiment that started by destroying the then reigning Aristotelian account. The latter holds that heavy bodies fall faster than light ones (H &gt; L). But consider Figure 6, in which a heavy cannon ball (H) and light musket ball (L) are attached together to form a compound object (H+L); the latter must fall faster than the cannon ball alone. Yet the compound object must also fall slower, since the light part will act as a drag on the heavy part. Now we have a contradiction: H+L &gt; H and H &gt; H+L. That’s the end of Aristotle’s theory. But there is a bonus, since the right account is now obvious: they all fall at the same speed (H = L = H+L).