In my opinion, this antithesis of monism and dualism is the most important in the whole history of philosophy.
In the transition from dualism to monism Malebranche served as a mediator.
As realism generally coincides with monism, so idealism is usually identical with dualism.
Plato's is an anthropological dualism, Aristotle's, a monism.
But if we examine the way in which they carried out their monism, we shall see that it broke down in a hopeless dualism.
But the pleading which monism is here able to supply can never be silenced.
The inner essence of things may at any rate be approached by a monism of matter or of energy.
Just as necessarily does it belong to the essence of monism to affirm the agency of Will.
They led him direct to monism and to an admiration of Spinoza's monistic pantheism.
And here it is that I think the theory of monism comes to the rescue.
"the philosophical doctrine that there is only one principle," 1862, from Modern Latin monismus, from Greek monos "alone" (see mono-). First used in German by German philosopher Baron Christian von Wolff (1679-1754).
A position in metaphysics that sees only one kind of principle whereas dualism sees two. On the question of whether people's minds are distinct from their bodies, for example, a monist would hold either that mental conditions are essentially physical conditions (materialism), or that bodies depend on minds for their existence (idealism).