We Name Ideas After Their Outputs

February 13, 2014

In philosophy of mind, there’s an interesting question about how a physical structure in the brain can have “mental content” or also how a physical structure, such as a set of neurons, can cause actions in the world. This is related to the concept of intentionality, of course, and my answer to all these questions is energy flow.

Bamboo in Kinuta Park - Nov. 10, 2013

Bamboo in Kinuta Park – Nov. 10, 2013 (Enlarge)

If you have a belief, that belief must have some kind of content, right? You believe there’s a beer in the fridge. So how does the physical structure of the belief – the neurons and their connections – connect to the beer? Surely there are no little icons in your brain representing beer. The answer is that energy flows through that neural construct in your brain and out through your motor neurons – and eventually into the beer.

How does the energy flow into the beer? Maybe it literally hits the beer in the form of kinetic energy, insofar as your motor impulses cause your hand to reach out and take the beer. Or maybe the neural energy follows motor nerves to your throat causing you to say, “I want a beer,” which in turn causes someone else to get the beer. Or maybe the energy flow is even more indirect, but my point is that your belief is about beer because energy actually flows in various forms from your belief to the beer.

I took this beer example from Christian philosopher Alvin Plantinga’s recent interview on a New York Times blog. In that interview, Plantinga said something I found downright preposterous:

It’s by virtue of its material, neurophysiological properties that a belief causes the action. It’s in virtue of those electrical signals sent via efferent nerves to the relevant muscles, that the belief about the beer in the fridge causes me to go to the fridge. It is not by virtue of the content (there is a beer in the fridge) the belief has.

Plantinga is claiming that the physical arrangement of neurons is different from the content of the belief. This is superficially true, of course, because there aren’t little beer icons in our brains. But it’s also a trivial and rather silly point to make. You could just as well say that a gun is different from the target it shoots. A hose squirting water is different from the bucket it fills. An electrical circuit is different from a lightbulb shining. Does Plantinga really not see any connection between the one thing and the other?

He continues:

If this belief – this structure – had a totally different content (even, say, if it was a belief that there is no beer in the fridge) but had the same neurophysiological properties, it would still have caused that same action of going to the fridge.

This is where Plantinga gets really preposterous because he’s assuming that an idea’s physical structure (set of neurons) has no connection whatsoever with the idea’s content. He doesn’t understand that “going to the fridge” is the idea’s content. That’s how we name our ideas. The content is the output of the energy flow through that neural construct.

I wonder if Plantinga would argue that a gun’s shape has no connection with the way the bullet shoots out. Or that a water hose’s shape has no influence on how the water squirts out. Or that the structure of a digital-electronic circuit has no influence on the circuit’s output.

A neural construct (set of neurons) works just like an electrical circuit with input, processing and output. What we call the content of a neural construct is its output. That’s just how we name our ideas – in terms of their outputs.

Let’s consider the simplest possible idea. It’s really nothing more than a pipe, a single conduit, like a wire that can conduct electricity. At one end is an input sensor, and at the other end is a tiny switch that turns on a light bulb.

When the sensor gets input, some kind of current flows along the idea wire to the switch, and the light bulb goes on. That’s all it does. Every time this “idea” gets its input, it produces the same output of turning on the light.

How does the idea cause the light to go on? Because of electrical current flowing.

What is the “mental content” of this idea? It’s the idea of turning the light on.

1 Comment

  1. im-skeptical says:

    It is obvious that one can think about something without any muscular activity, or without establishing any kind of physical connection to it. The existence of “icons” in the brain is probably closer to the truth. We make mental models of the world by establishing neural connections between various mental objects (which you can think of as icons). These objects consist of nothing more than neurons that represent concepts. By connecting concepts together with neural pathways, we establish meaning. This is also the basis of “aboutness”. It really is a matter of physical connections. But not connections to the actual objects in the world – it is connections to our mental objects that represent those things.