My mother died this morning. She was on life-support for hours as we agonized about when to let her go. Was her brain already dead, or was there a chance she could wake? We decided that if her heart stopped again, they should not do another CPR. Then her EKG line gradually faded away. Did she die at that moment?
I realized only recently that when I talk about death with others, there is some missing common ground between their views and mine. It’s easy to get caught up in arguing ethical choices and not realize that we don’t even share the same definitions. Many people work with traditional notions: death is when your heart stops beating or you stop breathing. Something similar can be said about the start of life.
This is my attempt to write down a careful account of my definitions and assumptions, to help with discussion. Thanks for taking the time to understand.
I do research in artificial intelligence (AI), particularly brain-inspired (neuromorphic) computing. There are only a few hundred people in the world who share this discipline. We design chips and software that process information using a simplified version of nerve impulses. I am deeply biased to think of the brain as a machine and the mind as information inside that machine.
In what sense is the brain a machine? It is a collection of atoms organized in a very particular way. When something happens in one part, it cause stuff to happen in other parts. All those interactions work together to control your body and process what you see and hear.
Your mind is the “state” of your brain. In a regular computer, “state” would be all the ones and zeros in memory. In the brain, state would include a lot of things, such as which neuron connects to which, how much voltage is on cell membranes, and the concentration of chemicals at certain places. Just like a computer, these are constantly changing according to rules built into the structure. The actual picture is more complicated and subtle, but this is sufficient for the sake of discussion.
Imagine that the human mind could be put into a regular computer. This is a rather controversial idea, even among AI researchers. However, it lets us make some useful analogies.
My definition of death is the permanent loss of information. If a neurosurgeon goes in and cuts out a part of my brain, the information contained in that piece dies. Maybe it is only 1% of my brain. Afterward, I am 99% of what I used to be. That is a partial death.
When part of the brain is damaged, there is a corresponding and predictable damage to the mind. IE: damage to Broca’s area impairs speech. A blow to the back of the head affects vision. Messing with serotonin re-uptake changes rational behavior. The deterioration of Alzheimer’s produces genuine changes of personality.
In computers there is a neat separation between machine structure and the information in it. Not so with brains. That’s why you can undergo anesthesia and come back to yourself again. Brain activity gets disrupted for a while, but nearly all of you is in the structure.
Some people point out that your mind resides in your body as well as your brain. This is because the structure of your body shapes how your brain processes. A similar argument could be made that your mind extends beyond your body into the surrounding environment, particularly the social structures you are part of.
While I agree with all this, it is a matter of degrees. I would guess that at least 99% of your mind is in your brain. That’s why people can get a spinal injury and still be themselves.
Suppose that some amazing new technology lets me make a backup of my brain, and from that backup we grow a replacement for the part that the neurosurgeon cut out a few paragraphs ago. I would be back to 100%. The loss is not permanent, so that part of me did not die.
As long as the information exists somewhere and can be restored, I’m in a kind of suspended animation. I only live if my mind actively runs on a computer or in a body. Being in storage creates the potential of future life. This potential is realized when the backup is either erased or restored.
(For computer experts only: This notion of mind-as-information creates some interesting scenarios. If mind can be captured in a backup, then it can be put under version control. It would be possible to have multiple branches and even merges. Then the question arises, what rights do each version of me have? The novel SuSAn explores this concept, particularly the chapters Susan Too and Custody.)
When my mother “died”, the material structure of her brain started to break down. This takes a while. Even though her brain could no longer function as a living organ, 99.99% of the structure was still there. After several hours there was still enough structure that my mother’s mind could be retrieved, if only we had the technology.
True death does not take place when the heart stops. It happens gradually over the next few hours. It makes me want to scream, the thought that my mom could still be saved, if only we had better brain-scanning technology. The fact is that we are letting her wither into oblivion right now because we’ve given up. We passively let souls be destroyed because we’ve never conceived of another possibility. Some day our descendants will look back on this era in horror.