Reference request: Skeptics of classical threshold theorem
It has been a while since I read von Neumann's paper, but I don't recall having the same impression that Scott Aaronson had. It seemed to me that von Neumann was addressing an argument that human brains must be qualitatively different from computers, because while human brains' individual components, neurons, are unreliable, human brains on a whole are much more reliable than electronic computers are.

While Claude Shannon does not actually make this argument explicitly in his 1953 paper "Computers and Automata" (it's quite possible other people did), he certainly brings up the question of reliability and brains. I have extracted a few sentences below:


  The brain has often been compared, perhaps overenthusiastically,
  with computing machines.
  ...
  Comparisons of this sort should be taken well salted—our understanding of brain functioning is still, in spite
  of a great deal of important and illuminating research,
  very primitive.
  ...
  The similarities between the brain and computers
  have often been pointed out. The differences are perhaps
  more illuminating, for they may suggest the important
  features missing from our best current brain
  models. Among the most important of these are:
  ...
  3. Differences in reliability organization. The brain
  can operate reliably for decades without really serious
  malfunctioning (comparable to the meaningless
  gibberish produced by a computer in trouble
  conditions) even though the components are probably
  individually no more reliable than those used
  in computers.