Roger Penrose is a guy who has a way of asking good questions and providing controversial answers. On page 20 of his monumental survey of applied mathematics, " The Road To Reality"  he explains an interesting theory about three "worlds": R*:The "real", physical world of "stuff" and phenomena, which he (quite reasonably) takes to exist apart from the other two worlds; M:The world of ideas - what I call the "meme space". In principle, this is all the theories, observations, direct or indirect perceptions that could ever be made by the human mind; F:The world of forms, mathematics and logic. While he contends is that each world "maps"  completely  to the others. In principle at least, each world can be explained in terms of the other.  But he allows us to imagine that the mapping is incomplete. It is the incompleteness that interests me: There may be aspects of reality that are "illogical" or cannot be described by mat...

The "R" meme is the most powerful and widely-shared meme: that there is a "real world out there" independent of our minds. This is the intuitive insight that is denied or at least challenged by "Idealism" [1]. Denial of R turns out to be a powerful " intuition pump ". We imagining that the "real world" does not exist at all, and it's "all in our minds". This is a rather strong denial of Idealism, since an Idealist would, I think, admit that the real world exists -- just that we can't know anything about it other than what pops up in our minds. At the risk of spoiling the plot, the view of this blog is that the brain can be thought of as a fantastically complex and specially-constructed knot that intimately ties the mind M to the world R. This connection is so intimate that it is, in practice, impossible to say where mind ends and world begins [2]. In effect, this frames "Idealism" as a discussion about a dis...