Searle: Is the Brain a Digital Computer?

Is the Brain a Digital Computer?

1.  On the standard textbook definition, computation is defined syntactically in terms of symbol manipulation.

  2.  But syntax and symbols are not defined in terms of physics. Though symbol tokens are always physical tokens, "symbol" and "same symbol" are not defined in terms of physical features. Syntax, in short, is not intrinsic to physics.

  3.  This has the consequence that computation is not discovered in the physics, it is assigned to it. Certain physical phenomena are assigned or used or programmed or interpreted syntactically. Syntax and symbols are observer relative.

  4.  It follows that you could not discover that the brain or anything else was intrinsically a digital computer, although you could assign a computational interpretation to it as you could to anything else. The point is not that the claim "The brain is a digital computer" is false. Rather it does not get up to the level of falsehood. It does not have a clear sense. You will have misunderstood my account if you think that I am arguing that it is simply false that the brain is a digital computer. The question "Is the brain a digital computer?" is as ill defined as the questions "Is it an abacus?", "Is it a book?", or "Is it a set of symbols?", "Is it a set of mathematical formulae?"

  5.  Some physical systems facilitate the computational use much better than others. That is why we build, program, and use them. In such cases we are the homunculus in the system interpreting the physics in both syntactical and semantic terms.

  6.  But the causal explanations we then give do not cite causal properties different from the physics of the implementation and the intentionality of the homunculus.

  7.  The standard, though tacit, way out of this is to commit the homunculus fallacy. The humunculus fallacy is endemic to computational models of cognition and cannot be removed by the standard recursive decomposition arguments. They are addressed to a different question.

  8.  We cannot avoid the foregoing results by supposing that the brain is doing "information processing". The brain, as far as its intrinsic operations are concerned, does no information processing. It is a specific biological organ and its specific neurobiological processes cause specific forms of intentionality. In the brain, intrinsically, there are neurobiological processes and sometimes they cause consciousness. But that is the end of the story.

Any analogy between the brain and a computer can only be pushed so far, but I've only ever heard the brain described as "analogue" rather than "digital".

Any analogy between the brain and a computer can only be pushed so far, but I've only ever heard the brain described as "analogue" rather than "digital".

http://www.salud.carlosslim.org/english2...is-analog/

Any analogy between the brain and a computer can only be pushed so far, but I've only ever heard the brain described as "analogue" rather than "digital".

Perhaps not specifically but there are surely plenty of analogies between brain and computer without specifying "digital computer". It is probably taken as read to mean digital because today's computers are digital (I could hardly find a reference to an operational analogue computer since digital has been predominant since the 1950s).

https://en.wikipedia.org/wiki/Analog_computer

I wonder whether it would make any difference to those 8 points in the OP if the term used was not "digital computer" but simply, "computer"?

Perhaps not specifically but there are surely plenty of analogies between brain and computer without specifying "digital computer". It is probably taken as read to mean digital because today's computers are digital (I could hardly find a reference to an operational analogue computer since digital has been predominant since the 1950s).

https://en.wikipedia.org/wiki/Analog_computer

I wonder whether it would make any difference to those 8 points in the OP if the term used was not "digital computer" but simply, "computer"?

I've no idea what those 8 points are trying to prove, so can't say for sure.

I've no idea what those 8 points are trying to prove, so can't say for sure.

Fair enough. Neither have I. 

Perhaps not specifically but there are surely plenty of analogies between brain and computer without specifying "digital computer". It is probably taken as read to mean digital because today's computers are digital (I could hardly find a reference to an operational analogue computer since digital has been predominant since the 1950s).

https://en.wikipedia.org/wiki/Analog_computer

I wonder whether it would make any difference to those 8 points in the OP if the term used was not "digital computer" but simply, "computer"?

Of course, there was a precursor to both digital and analogue computers. In a previous era, the term 'computer' was a job description, like 'bank clerk' or 'labourer'. A computer used to be a person.

Is the Brain a Digital Computer?

I think the brain is a kind of computer, but the analogy is incomplete because we have not exploited physics to its fullest potential to realize the computational power of matter. We seem to exist in a database or matrix where semantic connections made in the mind have an objective reality that extends beyond the phyiscal brain. No one knows how it works yet, but no synthetic computer will be complete without understanding and implementing this semantic layer of physics/reality.

We can consider the universe to be a computer and the individual person to be a subset of universal computation.

I think the brain is a kind of computer, but the analogy is incomplete because we have not exploited physics to its fullest potential to realize the computational power of matter. We seem to exist in a database or matrix where semantic connections made in the mind have an objective reality that extends beyond the phyiscal brain. No one knows how it works yet, but no synthetic computer will be complete without understanding and implementing this semantic layer of physics/reality.

We can consider the universe to be a computer and the individual person to be a subset of universal computation.

Do you mean "computer" as in there is an input/output, or computer as in a Turing Machine? What is a "subset of universal computation", as in what is running the programs? For example, here's some stuff out there suggesting reality is Idealist and it is the Mind of God that runs the computer, or there are two frames of reality - the "physical" one of information and the higher frame where consciousness interacts with this information.

Also see Hammeroff talking about quantum structures vs a Turing Machine type device, given your previous writings re: God/Order/Abyss I'd be curious to know if what you mean is closer to something like this:

Is your brain really a computer, or is it a quantum orchestra tuned to the universe?

In a New York Times piece ‘Face It, Your Brain is a Computer’ (June 27, 2015), NYU psychologist/neuroscientist Gary Marcus desperately beat the dead horse. Following a series of failures by computers to simulate basic brain functions (much less approach the ‘C-word’, consciousness) Marcus is left to ask, in essence, if the brain isn’t a computer, what else could it possibly be?

Actually, rather than a computer, the brain is looking like a multi-scalar vibrational resonance system – not unlike an orchestra. Rather than a computational output, consciousness seems more like music.

Like many natural systems, dynamical brain information patterns repeat over spatiotemporal scales in fractal-like (‘1/f’) nested hierarchies of neuronal networks, with resonances and interference beats. One example of a multi-scalar spatial mapping is the 2014 Nobel Prize-winning work (O’Keefe, Moser and Moser) on ‘grid cells’, hexagonal representations of spatial location arrayed in layers of entorhinal cortex, each layer encoding a different spatial scale of surrounding environment. Moving from layer to layer in entorhinal cortex is precisely like zooming in and out in a Google map.

Indeed, neuroscientist Karl Pribram’s assessment of the brain as a ‘holographic storage device’ (which Marcus summarily dismissed) seems now on-target. Holograms encode distributed information as multi-scalar interference of coherent vibrations, e.g. from lasers. Pribram lacked a proper coherent source, a laser in the brain, but evidence now points to coherent dynamics in ubiquitous structures called microtubules inside brain neurons as high frequency origins of the brain’s vibrational hierarchy, the drumbeat, or percussion section of the orchestra.

Any analogy between the brain and a computer can only be pushed so far, but I've only ever heard the brain described as "analogue" rather than "digital".

It is worth pointing out that any analogue computer can be simulated  by a digital one to whatever level of precision is required. Indeed, much of the research on neural nets is done using computer simulation of a rather crude approximation to an actual net of neuron cells.

I think this is part of the puzzle - that different types of digital computers all have the same theoretical power as a Turing machine (assuming it has adequate memory and speed considerations are not important), and going analogue can't really help for the above reason. As far as I understand it, even quantum computers only offer a speed advantage - they don't enable new types of computation to be performed - but I might be wrong.