Supposing that neurons function similarly to transistors: A neuron able to fire $200$ times per second and transistors can be switched on and off more than $100,000,000,000$ ($10^{11}$) times per second. Let's say it fires 1 out of 2 times in average.We have $86,000,000,000$ ($8.6 \cdot 10^{10}$) neurons in a brain, and $4,000,000,000$ ($4 \cdot 10^9$) transistors in medium CPU.$\text{Units count} \cdot \text{firing probability} \cdot \text{firing rate} = \text{total fires per second}$A brain's total fires per second: $(8.6 \cdot 10^{10}) \cdot 1 \cdot 200 = 1.72 \cdot 10^{13}$.A CPU's total fires per second: $(4 \cdot 10^9) \cdot \frac{1}{2} \cdot 10^{11} = 2 \cdot 10^{20}$.A CPU is faster than a brain by $\frac{2 \cdot 10^{20}}{1.72 \cdot 10^{13}} = 1.16 \cdot 10^7$, or about 12 million times faster. I gave the brain an advantage that every neuron is firing non-stop instead of just 1%, and that they fire at the rate of the fastest neurons.Why isn't this argument valid?
Why do scientists say brains are faster than computers?
neurobiology;theoretical neuroscience
There is a basic epistemological problem here that was only touched upon by Chuck Sherrington - everyone is making the assumption that the brain processes the same kind of information as a digital computer. There is no real evidence to suggest that it does, in fact. A digital computer is an instantiation of a Turing machine, which is equivalent to certain kinds of automata. In order for the processing power of the brain to be compared to that of a digital computer in the first place, one needs to show that the brain employs representations (discrete entitites/states like bits) and rules (well-defined transitions between states/bits). Nobody has even come close to doing this, even for a subsection of the brain. This would be done by showing that the brain implements some digital computation - David Chalmers' famously [1] explains how this needs to be done. According to current the state of research, the brain seems to be a complex biological system, operating at multiple levels of measurement, and does not process information in discrete terms! And yes, Chuck Sherrington says it, neurons are not simply on/off![1] Chalmers, David J. A computational foundation for the study of cognition. (1993).