You are in the future with technologies more advanced than today’s. While you are sleeping, some group scans your brain and picks up every salient detail. Perhaps they do this with blood-cell–sized scanning machines traveling in the capillaries of your brain or with some other suitable noninvasive technology, but they have all of the information about your brain at a particular point in time. They also pick up and record any bodily details that might reflect on your state of mind, such as the endocrine system. They instantiate this “mind file” in a nonbiological body that looks and moves like you and has the requisite subtlety and suppleness to pass for you. In the morning you are informed about this transfer and you watch your mind clone, whom we’ll call You 2. You 2 is talking about his or her life as if s/he were you, and relating how s/he discovered that very morning that s/he had been given a much more durable new version 2.0 body. “Hey, I kind of like this new body!” s/he exclaims.
If you were to, uh, disappear, no one would notice. You 2 would go around claiming to be you. All of your friends and loved ones would be content with the situation and perhaps pleased that you now have a more durable body and mind. Maybe your more philosophically minded friends would express concerns, but for the most part, everybody would be happy, including you, or at least the person who is convincingly claiming to be you.
So we don’t need your old body and brain anymore, right? OK if we dispose with it?
You’re probably not going to go along with this. Your sense of identity is still with you, not with You 2. Our conclusion? You 2 is conscious but is a different person than you—You 2 has a different identity. S/he is extremely similar, much more so than a mere genetic clone, because s/he also shares all of your neocortical patterns and connections. Or I should say s/he shared those patterns at the moment s/he was created. At that point, the two of you started to go your own ways, neocortically speaking. You are still around. You are not having the same experiences as You 2. Bottom line: You 2 is not you.
Now consider another thought experiment—one that is, I believe, more realistic in terms of what the future will bring. You undergo a procedure to replace a very small part of your brain with a nonbiological unit. This is not so far-fetched, as it is done routinely for people with neurological and sensory impairments, such as the neural implant for Parkinson’s disease and cochlear implants for the deaf. As promised, the procedure works just fine—certain of your capabilities have improved. (You have a better memory, perhaps.) So are you still you? There is no good argument that you’re suddenly a different person.
Encouraged by these results, you now decide to have another procedure, this time involving a different region of the brain. The result is the same: You experience some improvement in capability, but you’re still you. You keep opting for additional procedures, your confidence in the process only increasing, until eventually you’ve changed every part of your brain. Each time the procedure was carefully done to preserve all of your neocortical patterns and connections so that that you have not lost any of your personality, skills, or memories. There was never a you and a You 2; there was only you.
Our conclusion: You still exist. There’s no dilemma here. Everything is fine.
Except for this: You, after the gradual replacement process, are entirely equivalent to You 2 in the prior thought experiment (which I will call the scan-and-instantiate scenario). You, after the gradual replacement scenario, have all of the neocortical patterns and connections that you had originally, only in a nonbiological substrate, which is also true of You 2 in the scan-and-instantiate scenario. You, after the gradual replacement scenario, have some additional capabilities and greater durability than you did before the process, but this is likewise true of You 2 in the scan-and-instantiate process.
We naturally undergo a gradual replacement process. Most of our cells in our body are continually being replaced. (You just replaced 100 million of them in the course of reading the last sentence.) Cells in the inner lining of the small intestine turn over in about a week. The life span of white blood cells range from a few days to a few months, depending on the type. Neurons persist, but their organelles and their constituent molecules turn over within a month. So you are completely replaced in a matter of months. Are you the same person you were a few months ago? Certainly there are some differences. Perhaps you learned a few things. But you assume that your identity persists, that you are not continually destroyed and recreated.
Fundamentally, we are not the stuff that makes up our bodies and brains. These particles essentially flow through us in the same way that water molecules flow through a river. We are a pattern that changes slowly but has stability and continuity, even though the stuff comprising the pattern changes quickly. The gradual introduction of nonbiological systems into our bodies and brains will be just another example of the continual turnover of parts that comprise us. It will not alter the continuity of our identity any more than the natural replacement of our biological cells do. We have already largely outsourced our historical, intellectual, social, and personal memories to our devices and the cloud. The devices we interact with to access these memories will become smaller and smaller, making their way into our bodies. It will be a useful place to put them—we won’t lose them that way. And in the coming years, we will continue on the path of the gradual replacement and augmentation scenario until ultimately most of our thinking will be in the cloud.
Reprinted by arrangement with Viking, a member of Penguin Group (USA) Inc., from How To Create a Mind. © Ray Kurzweil, 2012.