Principles of Human Action: Epistemological vs. Metaphysical Possibility

Epistemological vs. Metaphysical Possibility (optional material)

In English, the distinction between epistemological and metaphysical possibility is reflected in contrasting syntactical constructions. As illustrated below, the phrase "it is possible that ..." typically introduces an observation regarding epistemological possibility, whereas "it is possible for ..." signals metaphysical possibility.

Epistemological Possibility:	Metaphysical Possibility:
It is possible that the Concorde is flying faster than the speed of sound.	It is possible for Concordes to fly faster than the speed of sound.

The difference in meaning between the two statements should be clear to alert users of the language. The two categories of possibility are also often differentiated by "may" and "can":

Epistemological Possibility:	Metaphysical Possibility:
The Concorde may be flying faster than the speed of sound.	The Concorde can fly faster than the speed of sound.