Consicousness is so familiar that it is hard to appreciate what an odd phenomenon it is. We tend to take our consicousness for granted and not wonder about its origins and grounds. Let us then try to step back from our consicousness and defamiliarize it. In particular, let us try to develop a sense of the oddity of the mind-brain link. We can start with an extract from a clever science fiction story by the writer Terry Bisson. (The link between mind and brain can seem like pure science fiction.) It takes the form of a conversation between an alien explorer who has visited earth and his commander:

"They're made out of meat."

"Meat?"...

"There's no doubt about it. We picked several from different parts of the planet, took them aboard our recon vessels, probed them all the way through. They're completely meat."

"Ther's impossible. What about the radio signals? The messages to the stars?"

"They use the radio waves to talk, but the signals don't come from them. The signals come from machines."

"So who made the machines? That's who we want to contact."

"They made the machines. That's what I'm trying to tell you. Meat made the machines."

"That's ridiculous. How can meat make a machine? You're asking me to believe in sentient meat."

"I'm not asking you, I'm telling you. These creatures are the only sentient race in the sector and they're made out of meat."

"Maybe they're like the Orfolei. You know, a carbon-based intelligence that goes through a meat stage."

"Nope. They're born meat and they die meat. We studied them for several of their lifespans, which didn't take too long. Do you have any idea of the life span of meat?"

"Spare me. Okay, maybe they're only part meat. You know, like the Weddilei. A meat head iwth an electron plasma brain inside."

"Nope, we thought of that, since they do have meat heads like the Weddilei. But I told you, we probed them. They're meat all the way through."

"No brain?"

"Oh, there is a brain all right. It's just that the brain is made out of meat!"

"So... what does the thinking?"

"You're not understanding, are you? The brain does the thinking. The meat."

"Thinking meat! You're asking me to believe in thinking meat!"

"Yes, thinking meat! Conscious meat! Loving meat. Dreaming meat. The meat is the whole deal! Are you getting the picture?"
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We can state the problem this way: Isn't there some kind of violation of the uniformity of nature in the fact that brains produce consciousness? Brains seem very similar to other parts of animal bodies, being basically a big collection of cells organised according to biochemical principles. Yet there is a yawning chasm between the natures of these entities, because brains produce consicousness and those other meaty organs do not, not even a little bit. This fundamental difference is not predictable from the physical similarities we observe. If we were to observe all the body parts apart from brains, we would arrive at the conclusion that body parts do not produce consciousness. But then we encounter brains and are brought up short. They violate the natural belief that collections of cells do not generate minds.

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