David Marr’s Concept of a Computational Theory for Understanding
an Information Processing Task in the Brain
Therefore, even if some day we had complete
knowledge of every molecule in the brain, and could
record the electrical activities of every cell at any time,
we would still not understand how the brain processes
information.  We need, in addition, a computational
theory which specifies how the electrical signals carried
by a large number of neurons could act in concert to
solve a certain perceptual problem.