The interesting thing about the second monism passage in SO is that it
pretends, but does not quite manage, to be symmetrical:
Monism, which implies a oneness of basic reality, is seen
to be divisible when, say, "mind" sneakily splits away from
"matter" in the reasoning of a muddled monist or halfhearted
materialist.
What one might have expected, for parallelism, is "muddled idealist or
half-harted materialist." It seems that VN equates monism with
idealism. One of his main goals in chapter four of The Gift is
to show that Chernyshevski's materialism is rife with hidden idealist
assumptions. Hence it may be that, in his mind, all materialism is
muddled, if not necessarily half-hearted. But, readers are right to be
suspicious of the apparent unequivocality of such Nabokovian statements.
As for Bergson, I think I remember that Dana Dragunoiu mentions Leona
Toker's article on Nabokov, Bergson, and ?Berkeley? from ?Russian
Literature Triquarterly?--I'm away from my research computer right
now--suggesting that Bergson is not a true monist. I have not had time
to re-look at original materials, definitions, etc. DD (dissertation)
also mentions Bertrand Russell's version of "neutral monism", and much
else besides. It was a very lively and "hot" topic from the 1890s up
to the 1920s, as far as I can tell. The old journal The Monist,
along with its sister journal The Open Court, both edited by
Paul Carus, published many fascinating pieces in this debate.
Stephen Blackwell