From an evolutionary standpoint, why does pain exist? The first naive answer most people reach for is that pain exists to make us take action to prevent damage. If we touch a hot stove, pain makes us pull our hand back.
But that’s not right. When we touch a hot surface, nociceptors in our hand send signals to the spinal cord, which often respond with a reflexive reaction, such as a withdrawal reflex. When the signal makes it to the brain, further automatic survival action patterns may be triggered, such as reflexively scrambling to get away.
But all of this can happen before, or independent of, the conscious experience of pain. So why then do we have the experience itself? It isn’t necessarily to motivate immediate action. The reflexes and survival circuitry often take care of that.
I think the reason we feel pain is to motivate future action. Feeling pain dramatically increases the probability that we’ll remember what happens when we touch a hot stove, that we’ll learn that’s it’s a bad move. If the pain continues, it also signals a damaged state which needs to be taken into account in planning future moves.
So then pain is information, information communicated to the reasoning parts of the brain, and serves as part of the motivation to learn or engage in certain types of planning.
People often dislike the conclusion that pain, or any other mental quality, is information. It seems like it should be something more. This dislike is often bundled with an overall notion that consciousness can’t be just information processing. What’s needed, say people like John Searle and Christof Koch, are the brain’s causal powers.
But I think this reaction comes from an unproductive conception of information.
I’ve often resisted defining “information” here on the blog. Like “energy”, it’s a very useful concept that is devilishly hard to define in a manner that addresses all the ways we use it.
Many people reach for the definition from Claude Shannon’s information theory: information is reduction in uncertainty. That definition is powerful when the focus is on the transmission of information. (Which of course, is what Shannon was interested in.) But when I think about something like DNA, I wonder what uncertainty is being reduced for the proteins that translate it into RNA? Or the ones that replicate it during cell division?
Historically, when pressed for my own definition, I’ve offered something like: patterns that, due to their causal history, can have effects in a system. While serviceable, it’s a bit awkward and not something I was ever thrilled with.
Not that long ago, in a conversation about information in the brain, philosopher Eric Schwitzgebel argued simply that information is causation. The more I think about this statement, the more I like it. It seems to effectively capture a lot of the above in a very simple statement. It also seems to capture the way the word is used from physics, to Shannon information, to complex IT systems.
Information is causation.
This actually fits with something many neuroscientists often say: that information is a difference that makes a difference.
This means an information processing system is effectively a system of concentrated causality, a causal nexus. The brain in particular could be thought of as a system designed to concentrate causal forces for the benefit of the organism. It also means that saying it’s the causal powers that matter rather than information, is a distinction without a difference.
The nice thing about this definition is, instead of saying pain is information, we can say that pain is causation. Maybe that’s easier to swallow?
What do you think? Is there something I’m missing that distinguishes pain from information? Or information from causation? If so, what?