Robin Hanson says

Bayesian probability is a great model of rationality that gets lots of important things right, but there are two ways in which its simple version, the one that comes most easily to mind, is extremely misleading.

One way is that it is too easy to assume that all our thoughts are conscious – in fact we are aware of only a tiny fraction of what goes on in our minds, perhaps only one part in a thousand. We have to deal with not only “running on error-prone hardware”, but worse, relying on purposely misleading inputs. Our subconscious often makes coordinated efforts to mislead us on particular topics.

I’m not so sure this makes sense. If we believe people are Bayesian actors then surely we mean that the unconscious part of the mind is Bayesian. First, its not entirely clear that the conscious mind is actually making any decisions whatsoever.

Split brain experiments suggest that it is likely that the conscious brain is simply narrating the decisions made by the unconscious. When the corpus callosum is cut the right cortex can no longer speak to the left cortex. Language is processed in the left hemisphere but sights from the left eye are processed in the right hemisphere (the body is cross wired.)

So what happens when we send an instruction to only the left eye? For example, an instruction to get up and leave the room. The body responds to the command and the person leaves the room.  But then what happens when we ask the left cortex what it is doing? It makes up a completely unrelated explanation. For example, it might say “I needed to go get a Coke.” Moreover, there is no evidence that the person is lying or that they even came up with the answer ex post.

It seems that as they were engaging in the action they had constructed a false narrative as to why they wanted to engage in the action. They were doing it because the experimenter told them to. But, they thought they were doing it because they wanted a Coke.

It could be that this odd behavior is unique to split brain patients. The rest of us might be completely aware of our motivations. Yet, it seems equally likely, perhaps more likely, that all of us are engaging in false narration all of the time. We are really controlled by calculations in our unconscious mind, which Robin points out, represents 99.9% of all of our thoughts. The conscious mind merely comes in behind weaves a story.

As a side note I will mention that this suggests that the conscious mind evolved for the purpose of co-coordinating actions between people and it is possible that other animals do not have a conscious self at all. Animal lovers may find this concept abhorrent but hear me out.

If the conscious mind is not the controller of the brain but merely the interpreter of the brain, then the question is, why does it exist at all. Clearly the mind can make decisions without it. Still, there are times when we might want other people to know what our rationale is. When we want them to understand where we are coming from. Humans engage in complex co-ordination that can only be possible if we understand what one another is thinking. To make that happen the brain has to weave together some easily communicable narrative to be transmitted to other brains.

I think this narrative is what we call our conscious minds. This is why our conscious minds present themselves running as internal conversation. That conversation is ready made material for giving others a snap shot of our unconscious thoughts.

But of course that’s just a thought.