In the recent book The Consciousness Instinct, neuroscientist Michael Gazzaniga writes about the brain and the mind. The subtitle of the book is Unraveling the Mystery of How the Brain Makes the Mind. The book is obviously written with the assumption that brains do make minds, a very dubious proposition there are many reasons for doubting. The book fails to make anything like a substantive defense of the claim that brains do make minds.
One of the key issues in whether brains make minds is how a brain could possibly generate any such thing as an abstract idea. Brains and neurons are physical things, but ideas are mental things. We can understand how a physical thing can generate another physical thing, and we can understand how a mental thing (a mind) can generate another mental thing (an idea). But no one understands how a physical thing (a brain or some neurons) could generate a mental thing (an abstract idea).
Looking at the index of Gazzaniga's book I see it has no entry for “idea.” But I do see four pages that refer to “thoughts.” Searching those pages, I find on page 8 what seems to be Gazzaniga's only description of how thoughts or ideas are created:
It is as if our mind is a bubbling pot of water. Which bubble will make it up to the top is hard to predict. The top bubble ultimately bursts into an idea, only to be replaced by more bubbles. The surface is forever energized with activity, endless activity, until the bubbles go to sleep.
As an attempt to explain the origin of ideas, this is a flop. A bubble is a physical thing, not a mental thing. When someone creates an abstract idea (such as the idea of a Trumper after viewing various zealous Trump supporters), such an abstraction (a mental act) bears no resemblance to a bubble floating up from hot water, a physical event which does not involve any observations. It may seem mysterious that bubbles pop up from water as it heats, but that's not an example of something appearing mysteriously. Water has some air trapped inside it, and the air just comes out as the water heats.
Water being heat up in a pot and producing bubbles is in several respects a very poor analogy for the creation of an idea. A human being will come up with a new idea only very slowly, and a human will only have one thought in his head at any single time. But in a heating pot of water, we see dozens of bubbles very quickly rising at the same time. When water starts to boil, it is a frothy chaos that bears no resemblance to the orderly thinking of a person trying to produce a new idea.
Not like a thinking mind
Again on page 206 and 207 Gazzaniga continues his bubble analogy, saying the following:
Thinking about this led me to use the metaphor of bubbling water as a way to conceptualize how our consciousness unfolds....The results bubble up from various modules like bubbles in a boiling pot of water....Each bubble has its own capacity to evoke that feeling of being conscious....Our smoothly flowing consciousness is itself an illusion.
Consciousness is certainly not an illusion, and there are no neurological facts supporting any such metaphor, or the idea that our smooth flow of consciousness is anything like a stream of individual bubbles.
On page 214-215 Gazzaniga gives us more bubble babble, and says “we have memory bubbles and feeling bubbles.” We are told, “As one bubble quickly passes to the next, we have the illusion of feeling about the remembered event.” No, the feelings we have when remembering important events are not illusions. A woman remembering being raped is not having an illusory emotion.