Category: Consciousness

Sometimes people object when I describe the human brain as a computer. The most common objections are things like:

• Computers are made by humans whereas brains are biological
• Computers are made out of silicon and our brains are made of cells
• Computers have addressable memory whereas our brains have neural networks
• Computers don't have emotions whereas we do
• Computers are mechanical whereas we have flexibility and free will

Some of the disagreement is simply arguing over definitions. If someone is using the word 'computer' to refer solely to devices made out of silicon designed by humans then of course they're not going to agree that human brains are computers. So let me short circuit some of the disagreement by making the following stipulative definition of 'computer':

A computer is a device that transforms input into useful output.

If we substitute in my definition, we can rephrase the question in the title of this post as "Is the human brain a device that transforms input into useful output?"

Using this definition, there doesn't seem to be much room for disagreement. The human brain takes input from the senses, and from internally stored information (for example memories), and transforms that input into useful behaviours.

If it really is fair to see the human brain as a computer, that suggests that we should be able to use much of the content of computer science to characterise and analyse the workings of the brain. We might expect to find some or all of the following concepts usefully applicable:

• Variables
• Subroutines
• Data encoding
• Memory storage and retrieval
• Lookup tables
• Ranking and sorting (eg in action prioritization subroutines)
• Daemon processes (processes with their own largely separate cause and effect chains)
• Concurrency
• Testing
• Bugs and debugging
• Caching
• Mechanisms optimised for speed or low resource usage or for accuracy
• Subsystems

and many others.

When discussing a topic as broad as human behaviour, it helps to make any philosophical/scientific assumptions explicit so that any reader can see if he or she has some fundamental difference of position to that of the author. I therefore give the following list of assumptions as axioms, which I take for granted elsewhere on the site (justifications/discussions are in the links [coming soon]):

1. The universe is deterministic. If precisely the same starting conditions are set up twice, precisely the same result will occur each time. Every process can therefore be described as mechanical, including consciousness.
2. Natural selection is the only known process in the universe capable of building complex adaptations.
3. "The ultimate goal that the mind was designed to attain is maximizing the number of copies of the genes that created it." (Steven Pinker)
4. It's legitimate to hypothesize about function in plain language or any computer language, even though functions are actually implemented in neurons, synapses etc in the brain. Functional hypotheses are at a layer of abstraction above implementation and can therefore be implementation-agnostic.

"We are survival machines — robot vehicles blindly programmed to preserve the selfish molecules known as genes." - Richard Dawkins - The Selfish Gene

"I am not apologizing for using the language of robotics. I would use it again without hesitation." - Richard Dawkins - The Extended Phenotype

"The ultimate goal that the mind was designed to attain is maximizing the number of copies of the genes that created it." - Steven Pinker - How The Mind Works

"Talk is cheap. Show me the code." - Linus Torvalds, creator of Linux operating system

"Those who study species from an adaptationist perspective adopt the stance of an engineer. In discussing sonar in bats, e.g., Dawkins proceeds as follows: "...I shall begin by posing a problem that the living machine faces, then I shall consider possible solutions to the problem that a sensible engineer might consider; I shall finally come to the solution that nature has actually adopted" (1986, pp. 21-22). Engineers figure out what problems they want to solve, and then design machines that are capable of solving these problems in an efficient manner. Evolutionary biologists figure out what adaptive problems a given species encountered during its evolutionary history, and then ask themselves, "What would a machine capable of solving these problems well under ancestral conditions look like?" Against this background, they empirically explore the design features of the evolved machines that, taken together, comprise an organism. Definitions of adaptive problems do not, of course, uniquely specify the design of the mechanisms that solve them. Because there are often multiple ways of achieving any solution, empirical studies are needed to decide "which nature has actually adopted". But the more precisely one can define an adaptive information-processing problem -- the "goal" of processing -- the more clearly one can see what a mechanism capable of producing that solution would have to look like. This research strategy has dominated the study of vision, for example, so that it is now commonplace to think of the visual system as a collection of functionally integrated computational devices, each specialized for solving a different problem in scene analysis -- judging depth, detecting motion, analyzing shape from shading, and so on." - Leda Cosmides & John Tooby - Evolutionary Psychology: A Primer

"In the distant future I see open fields for far more important researches. Psychology will be based on a new foundation, that of the necessary acquirement of each mental power and capacity by gradation. Light will be thrown on the origin of man and his history." - Charles Darwin - On the Origin of Species

"The human mind consists of a set of evolved information-processing mechanisms … produced by natural selection over evolutionary time." John Tooby and Leda Cosmides in The Adapted Mind

"Information and computation reside in patterns of data and in relations of logic that are independent of the physical medium that carries them." Steven Pinker - How The Mind Works

"The brain’s special status comes from a special thing the brain does, which makes us see, think, feel, choose, and act. That special thing is information processing, or computation." Steven Pinker - How The Mind Works

"I have a friend who's an artist, and he sometimes takes a view which I don't agree with. He'll hold up a flower and say, "Look how beautiful it is," and I'll agree. But then he'll say, "I, as an artist, can see how beautiful a flower is. But you, as a scientist, take it all apart and it becomes dull." I think he's kind of nutty. ... There are all kinds of interesting questions that come from a knowledge of science, which only adds to the excitement and mystery and awe of a flower. It only adds. I don't understand how it subtracts." - Richard Feynman

"You are a computer, built by selection, and melted or disordered by entropy." John Tooby