Ideas cause ideas and help evolve new ideas. They interact with each other and with other mental forces in the same brain, in neighboring brains, and thanks to global communication, in far distant, foreign brains. And they also interact with the external surroundings to produce in toto a burstwise advance in evolution that is far beyond anything to hit the evolutionary scene yet.His position is often described as mentalism and is rather controversial. This is made clearer, if it is not made clear enough by the quote itself, by what immediately precedes it: "Mental forces direct and govern the mental impulse traffic, including its electrochemical and biophysical aspects. ... In the brain model proposed here, the causal potency of an idea, or an ideal, becomes just as real as that of a molecule, a cell, or a nerve impulse."
Without pronouncing on the truth of this kind of mentalism, I would like to maintain that the claim that "ideas cause ideas and help evolve other ideas" is (also) true for someone of a more externalist persuasion. Just substitute "notes" for "ideas." It seems true to me that "notes cause notes and help evolve new notes," quite independently of my own intentions. That is one of the reasons why I find the phenomenon of "taking note" so interesting.
In this context it is also of interest that Sperry's quote turns up in many discussions of memes or mimetics.
1. Roger Sperry, "Mind, Brain and Humanist Values" (1965), p. 82.
2. But note--no pun intended--that I didn't say "altogether independently of my own intentions."
3. I just searched the blog, and I can't believe that I have not written about memes yet.