G.E. Moore was an important British philosopher of the early twentieth century. Along with Bertrand Russell and Ludwig Wittgenstein, he was one of the founders of the analytic philosophy approach that has been dominant in America and Britain.Ethics
In ethics, Moore focused on what "good" means and on how we can know that something is good. These became the central questions in ethical theory. Later thinkers agreed or disagreed with Moore's answers; but they all took seriously his questions and arguments. So Moore set the stage for further reflection on ethics.
These summaries and problems deal with Moore's Principa Ethica. These materials are copyrighted (c) 1998 by Harry J. Gensler but may be distributed freely.
Moore saw ethics as the general inquiry into what is good. To do ethics correctly, we must distinguish two questions:Good
(a) What is good in itself (intrinsically good)?Our answers to (a) are "intuitions" -- in the sense that we can know them to be true but can't prove them.
(b) What actions ought we to perform?
The general answer to (b) is that we ought to do whatever will bring about the best consequences. More concrete answers depend on our (rough and uncertain) judgments about consequences -- plus our appraisal of the intrinsic goodness of these consequences.
"Good" is a simple, unique, non-empirical notion that forms the ultimate reference point for ethics.Naturalism
"Good" can't be defined. This means that "good" isn't a complex that can be analyzed into simple notions. Rather, it's one of the simple notions on which any analysis ultimately rests.
We can specify those things to which "good" applies as an adjective. We can make true statements like "Pleasure is good."
Saying "Pleasure is good" joins two distinct concepts ("pleasure" and "good"). The two terms aren't synonymous. "Pleasure is good" doesn't mean "Pleasure is pleasure."
Naturalism defines "good" to be a natural (empirical) property, like pleasure or desire. Moore says that this confuses evaluative with non-evaluative notions and commits the naturalistic fallacy.
Suppose that someone defines "good" to mean "desired." This doesn't capture what we mean by "good" -- since we can significantly ask, "Are things that are desired always good?" This is an open question -- and doesn't just mean "Are things that are desired always desired?" So "good" and "desired" are distinct concepts.
The same argument works if we substitute any other natural property. So "good" is not identical to any natural property.
Since "good" is indefinable, moral statements aren't deducible from non-moral statements alone. As Hume's Law says, "You can't deduce an OUGHT from an IS."