Moore's Paradox

Many people who are not philosophers will have heard of Bertrand Russell, for Russell was not only an outstanding philosopher, but also a social activist and peace activist and an author of several novels. However, not many people, non-philosophers, will have heard of George Edward Moore, better known as G.E. Moore (1873-1958). Nevertheless, both have co-operated during their most fruitful philosophical years, and both were friends. Together with Ludwig Wittgenstein and Gottlob Frege Moore belonged to the founders of analytic philosophy, and together with Russell he led the turn from idealism in British philosophy. However, so Richard Monk, G.E. Moore disappeared from history, although he was the most revered philosopher of his era. The facts just mentioned plus Moore’s contribution to ethics, epistemology and metaphysics should have made him already a famous man, but his most important contribution to philosophy is, if we may believe Wittgenstein, the discovery of, what Wittgenstein called, Moore’s paradox. Wittgenstein treated this paradox extensively in his Philosophical Investigations (II, x) and his On Certainty and he gave it its name. Hadn’t he done so, the paradox might have been forgotten, but since then many philosophers have discussed it. Here it is:

“It is raining, but I do not believe that it is raining”
or formulated alternatively, which comes to the same:
“It is raining, but I believe that it is not raining.”

These sentences consist of two parts:
a - It is raining.
b - I believe it is not raining.

As such these two statements need not be contradictory, namely when they are said by two different persons, for instance:
John: “It is raining”
I: “I believe it is not raining. What you hear is the noise of a mouse tripping in the attic.”
However, the two sentences do become contradictory, if they are asserted by one person in connection. Why?
- It can be true at a particular time that it is raining, and that I do not believe that it is raining.
- I can believe that it is raining at a particular time and at another time I can believe that it is not raining.
So, I can believe that “it is raining” is true, and that “it is not raining” is true at another time, or I can doubt one of these assertions, if they are stated by someone else. However, it cannot rain and not rain at the same time, so a and b cannot be true at the same time. Therefore it is contradictory and absurd to assert “It is raining, but I do not believe that it is raining” (or “It is raining, but I believe that it is not raining.”), for then the speaker says that the fact that it rains is true and not true at the same time, which cannot happen.
However, my analysis just given (which is not really original, though, and made by many before me) is only correct if the sentence “It is raining, but I do not believe that it is raining” is asserted by one and the same person and refers to what is said by one and the same person, so if it is a first-person statement, and if both parts of the sentence are considered true. In fact, the sentence should be then “I believe that it is raining, but I do not believe that it is raining”. For instance, the sentence is not a paradox if the speaker actually wants to say “According to him it is raining, but I do not believe that it is raining” or “It seems that is raining, but I do not believe that it is raining [because what I hear is actually the tripping of a mouse].” The sentence can be true if it is changed to “It is raining, but he does not believe that it is raining”.
This is what Moore’s paradox is about. Wittgenstein used it to clarify the concept of belief. Since then, it keeps philosophers busy, and makes that Moore is not yet completely forgotten. However, there is much more that should keep George Edward Moore in our memory.