But, how can such mental events as beliefs and desires cause John's mouth to move in such a way that he orders dessert?
This troubles philosophers because intuitively it seems that mental states are crucial in causing a person to act (for example, their beliefs and desires).
Thomas Huxley famously noted that epiphenomenalism treats mental states like the steam coming off a train: it plays no causal role in the train's moving forward, it is merely an "emergent property" of the actual causation occurring in the engine (Walter 2003, p. §2) harv error: no target: CITEREFWalter2003 (help).
A common view in the philosophy of mind is that at least certain mental states have intentional content in this sense.
Given these types of considerations, some argue that it is appropriate to say that the main assumptions in interactionist dualism generate the problem of mental causation rather than solve it (see (Yoo 2006, p. §1a).
A more recent view, known as functionalism, claims that mental events are individuated (or constituted by) the causal role they play.
Related to dualism above, a more general and somewhat differently posed approach to mental causation is provided by Karl Popper's three worlds.
A still different approach to mental causation is based upon the philosophies of Kant, Chomsky and Pinker.
These philosophers stress the impact of built-in aspects of mind, studied in the field of psychological nativism.
[2] Immanuel Kant (1724–1804) pointed out that we all shape our experience of things through the filter of our mind, a view sometimes called epistemological solipsism.
The mind shapes that experience, and among other things, Kant believed the concepts of space and time were programmed into the human brain, as was the notion of cause and effect.
[3] The following observations summarize Kant's views upon the subject-object problem, called Kant's Copernican revolution: "It has hitherto been assumed that our cognition must conform to the objects; but all attempts to ascertain anything about these objects a priori, by means of conceptions, and thus to extend the range of our knowledge, have been rendered abortive by this assumption.
"[4]Although Kant has posed the issue of built-in aspects of mind, the particulars that depend upon the science of his day have become outmoded.
[5] According to Pinker, Charles Darwin himself "concluded that language ability is 'an instinctive tendency to acquire an art', a design that is not peculiar to humans but seen in other species such as song-learning birds."
[7] From this standpoint, as with the philosophy of Kant, the first-person active actions of mental causation may involve innate workings of the brain itself.