In philosophy, a Moorean fact is any fact that is so common-sensical that it need not be questioned. Because philosophy is based on questioning EVERYTHING, there is no such thing as a true Moorean fact.
The phrase comes from G.E. Moore's famous argument refuting idealism:
- Here is a hand.
- Here is another hand.
- There are at least two external objects. (From 1 & 2)
- Therefore an external world exists.
The idea that you are so certain of the material existence of your hands that there is no point in further thought or questioning is, of course, nonsense. However, it is quite common for a person to come across a new idea and reject it as useless and absurd speculation. The term Moorean fact can refer to any of these things that we know with more certainty than we know the premises of any argument to the contrary. Of course, if you think that this certainty is justified, you will probably call your assumptions a warrant or an axiom. Calling a statement a Moorean fact suggests that you think that it is an unwarranted, or at least questionable, assumption.