I have heard people write about a split brain experiment where a participant whose corpus collosum was severed was instructed in one ear, through a pair of headphones, to leave the room they were in because the experiment was over. As the participant stood to leave the room, a researcher asked them why they had gotten up. The participant said they wanted to get something to drink.
This experiment is pretty famous and demonstrates the human ability to rationalize our behaviors even when we really don’t know what prompted us to behave in one way or another. If you have ever been surprised that you had an angry outburst at another person, if you have ever had a gut feeling in an athletic competition, and if you ever forgot something important in a report and been bewildered by your omission, then you have probably engaged in post-action rationalization. You have probably thought back over the event, the mental state you were in, and tried to figure out exactly why you did what you did and not something else.
However, Judea Pearl in The Book of Why would argue that your answer is nothing more than an illusion. Writing about this phenomenon he says:
“Rationalization of actions may be a reconstructive, post-action process. For example, a soccer player may explain why he decided to pass the ball to Joe instead of Charlie, but it is rarely the case that those reasons consciously triggered the action. In the heat of the game, thousands of input signals compete for the player’s attention. The crucial decision is which signals to prioritize, and the reasons can hardly be recalled and articulated.”
Your angry traffic outburst was brought on by a huge number of factors. Your in game decision was not something you paused, thought about, and worked out the physics to perfect before hand. Similarly, your omission on a report was a barely conscious lapse of information. Each of these situations we can rationalize and explain based on several salient factors that come to mind post-action, but that hardly describes how our brain was actually working in the moment.
The brain has to figure out what signals to prioritize and what signals to consciously respond to in order for each of the examples I mentioned to come about. These notions should challenge our ideas of free-will, our beliefs that we can ever truly know ourselves, and our confidence in learning from experience. Pearl explains that he is a determinist who compromises by accepting an illusion of free will. He argues that the illusion I have described with my examples and his quote helps us to experience and navigate the world. We feel that there is something that it is like to be us, that we make our decisions, and we can justify our behaviors, but this is all merely an illusion.
If Pearl is right, then it is a helpful illusion. We can still understand it better, still understand how this illusion is created, sustained, and can be put to the best uses. We might not have a true and authentic self under the illusion. We might not be in control of what the illusion is. But nevertheless, we can shape and mold it, and have a responsibility to do the best with our illusion, even if much of it is post-action rationalization.