What if you don’t matter? What if all of your thoughts, precious feelings, great dreams, and terrible fears are completely, utterly, spectacularly irrelevant? Might it be that all of your mental life is just some pointless spectator, looking on as your body does the important stuff of keeping you alive and running about? What actually is the point of a thought?

This is the view of “epiphenomenalism,” and it might just be one of the most disturbing ideas in all of philosophy.

In this theory, consciousness is something that emerges from the sum of our cognitive processes — or, more specifically, the “capacity of a system to integrate information,” as Tononi writes. In other words, consciousness is a net product of all the other things our mind is doing, such as synchronizing sensory inputs, focusing on specific objects, accessing various types of memory, and so on. The mind is an overseer at the center of a huge web and is the result or byproduct of all the incredibly complex things it needs to do.

But if epiphenomenalism is correct, it means that our thoughts don’t add anything to the physical world that isn’t already ongoing. It means that we are locked in our heads. All the thoughts and feelings are ultimately pointless or nonsense. We are like children pretending to drive a car — it can be great fun, but we are really not in charge.