Fun Science Fact: The Subjective "I" is an Illusion

By Edward Ashton
Mar 2, 2019 · 847 words · 4 minutes


From the author: In which the author explains why you should not attempt to kill him in his sleep.


Here’s a fun thought experiment. Imagine that when you go to sleep at night, you don’t actually go to sleep. You die. You die, and when you wake up the next morning, it’s not you that wakes up. It’s somebody else. He’s got all your memories, and he thinks he’s you -- but he’s not. The next night, that guy dies, and somebody else wakes up in his place. Question:  Would that make any difference at all in your life? Would you even be able to tell?

The reason you even have to think about this question is this: Whether we admit it or not, we all think of ourselves as something like the things in Invasion of the Body Snatchers. These are my hands, attached to my arms, controlled by my brain. All of these things belong to me, but they’re not me. I’m an ineffable something that sits somewhere behind my eyes, inhabiting and controlling my body, but separate from it.

Except that I’m not. What I am in truth is an accidental result of the interactions of billions of neurons bouncing very simple electro-chemical signals off of one another. In principle, what I am isn’t materially different from what a termite nest is. Termites individually don’t have the slightest idea how to build the sort of complex structures that they build. The ability to do what they do is the result of chemical signaling between individual termites, none of whom actually has a plan for what they’re doing. In the same way, none of the individual neurons in my brain have any idea how to shoot a jump shot or write a sonnet or recite the alphabet in a single burp. And yet, these things get done.

Both the termites’ skills at architecture and my skill at coherent belching are examples of what is referred to as an emergent property. This is an old concept, describing situations in which something extremely complex arises from a great number of individually very simple interactions. Life itself, for example, can be seen as an emergent property of simple chemical processes.

Despite the fact that the concept of emergence has been around at least since Aristotle, however, we humans have a very difficult time fitting our heads around it. We see complexity, and assume that there must be complex planning underlying it. This is why it’s so difficult to convince many people that yes, the simple process of natural selection can, given sufficient time, produce an eyeball. For most folks, it’s probably even more difficult to stomach the fact that what are essentially a hundred billion simple logic gates electro-chemically zapping one another can produce Shakespeare.

The root of the problem is our inability to really internalize big numbers. Most of us know intellectually that a million is a thousand thousands, and that a billion is a thousand millions, but we don’t really feel it. We evolved in an environment where ten is a lot, whether we’re talking about bananas gathered or hours until sunset or miles left to walk. Any number much bigger than a hundred is an abstraction, and not really worth considering as far as our lizard-brains are concerned. As a result, the fact that we can get incredible complexity from the semi-random interactions of billions of simple elements, honed over tens of millions of years, doesn’t strike many of us as plausible. Despite that, though, it’s true.

So, how does this all relate back to the original question? I think most of us (myself included) would instinctively say that yes, it makes a big difference if I die when I go to sleep tonight, and an exact duplicate of me wakes up in the morning.  Nobody else might notice, but I’ll be dead, while that guy is walking around my house, wearing my favorite sweatshirt, and smooching my honey. But, that instinctive response is predicated on the idea (also instinctive) that there is such a thing as me. If that’s not true -- if all I really am is a manifestation of a standing wave function bouncing back and forth across the inside of my skull -- then all that matters is that the replicant has an exact re-creation of that pattern. If he does, then he’s not a copy of me. He is me. That instinct that says otherwise is really just vanity.

If you’re interested in a more in-depth exploration of this topic (at least in terms of what it would be like to die and be replaced by a replicant over and over again) check out The Ophiuchi Hotline, by John Varley. If you’re interested in how this concept could lead to you living forever in a robot body (hopefully not a roomba) check out pretty much anything by Ray Kurzweil. If you’re interested in killing me in my sleep and replacing me with an exact duplicate, be aware that I keep a baseball bat under my bed. Abstract theorizing about the nature of the self is all well and good, but sometimes you’ve gotta listen to your lizard-brain.