Philosopher Johannes Jäger has written an essay called The Cyborg Myth. It’s about us not being machines and I enjoyed it tremendously. Jäger’s writing is very clear, which means even I as a layperson can attempt to understand it. I hope he doesn’t come to regret this clarity, because it made me feel entitled to add my own, relatively uninformed opinions.
In an important way, I agree with Jäger: I don’t feel like a machine. I feel like Charlie Chaplin in The Great Dictator:
More than machinery, we need humanity. More than cleverness, we need kindness […] Don’t give yourselves to these unnatural men, machine men, with machine minds and machine hearts! You’re not machines! You’re not cattle! You’re men!
In other ways, while I mostly follow Jäger’s arguments, I don’t agree with his conclusions. He argues that it’s wrong to assume that organisms are machines. He attempts to disprove this by arguing against the substitution argument, which states that if we replaced every cell in our body with a machine that does the same thing, we’d still be ourselves in essence. Jäger believes our understanding of what cells do in our bodies is so incomplete that we couldn’t attempt such a substitution. This is a key passage in Jäger’s post:
Robert Rosen proved mathematically — using the theory of categories — that the category of living systems (without well-defined dynamic rules or state spaces) is fundamentally distinct from the category of machines (whose models are based on fixed rules and state spaces). This is called Rosen’s conjecture. It states that organisms are not computable (or simulable, as Rosen calls it), and has led to much controversy over the years, because the way it is formulated tends to confuse people. The problem is as follows: Rosen does not say that it is impossible to come up with simulations of a cell’s dynamic behavior; all he says is that these simulations won’t capture all the possible future dynamics. It is an incompleteness argument for the life sciences, analogous to Gödel’s incompleteness theorems for formal systems. Life cannot be completely formalized: it will always surprise us — its behavior and evolution truly open-ended indeed.
I am not qualified to judge if Rosen proved mathematically that organisms aren’t computable. However, don’t synthetic biology experiments like the transplantation of a bacterium with a synthetic genome, support the substitution argument for living systems? As Jäger acknowledges, what Rosen has and hasn’t proved is still controversial, which is why it’s a conjecture rather than a theorem.
But even if Rosen’s conjecture is true, I don’t think it invalidates the substitution argument. It’s not clear if we need to understand what a component does, or capture all of its possible future dynamics, to replicate its function. It’s not even clear if all of the functions need to be replicated. For example, it may be possible to substitute one cell with a quite different type of stem cell, which will then learn the important functions of the original cell on the job. If that’s possible, why wouldn’t it be possible to substitute the cell with another adaptive system?
Secondly, while I agree that the substitution argument lends support to organisms being machines, I’m not sure it’s strictly necessary. This also means that I don’t think that invalidating the substitution argument for living systems means that organism-machine equivalence is dead.
Thirdly, even if Jäger is correct and it turns out that organism-machine equivalence is actually dead, this doesn’t say anything about what machines can or can’t do. So what if they can’t self-replicate like living organisms? Why does that imply that they couldn’t develop sentience? I don’t see a reason why organism-machine equivalence is necessary for sentient machines to exist, yet this is the assumption Jäger makes in his blog post.
