Am I a Type or a Token? (guest post by Henry Shevlin)

guest post by Henry Shevlin

Eric has previously argued that almost any answer to the problem of consciousness involves “crazyism” – that is, a commitment to one or another hypotheses that might reasonably be considered bizarre. So it’s in this spirit of openness to wild ideas I’d like to throw out one of my own longstanding “crazy” ideas concerning our identity as conscious subjects.

To set the scene, imagine that we have one hundred supercomputers, each separately running a conscious simulation of the same human life. We’re also going to assume that these simulations are all causally coupled together so that they’re in identical functional states at any one time – if a particular mental state type is being realized in one at a given time, it’s also being realized in all the others.

The question I want to ask now is: how many conscious subjects – subjective points of view – exist in this setup? A natural response is “one hundred, obviously!” After all, there are one hundred computers all running their own simulations. But the alternate crazy hypothesis I’d like to suggest is that there’s just one subject in this scenario. Specifically, I want to claim that insofar as two physical realizations of consciousness give rise to a qualitatively identical sequence of experiences, they give rise to a single numerically identical subject of experience.

Call this hypothesis the Identity of Phenomenal Duplicates, or IPD for short. Why would anyone think such a crazy thing? In short, I’m attracted by the idea that the only factors relevant to the identity and individuation of a conscious subject are subjective: crudely, what makes me me is just the way the world seems to me and my conscious reactions to it. As a subject of phenomenal experience, in other words, my numerical identity is fixed just by those factors that are part of my experience, and factors that lie outside my phenomenal awareness (for example, which of many possible computers are running the simulation that underpins my consciousness) are thus irrelevant to my identity.

Putting things another way, I’d suggest that maybe my identity qua conscious subject is more like a type than a token, meaning that a single conscious subject could be multiply instantiated. As a helpful analogy, think about the ontology of something like a song, a novel, or a movie. The Empire Strikes Back has been screened billions of times over the years, but all of these were instantiations of one individual thing, namely the movie itself. If the IPD thesis is correct, then the same might be true for a conscious subject – that I myself (not merely duplicates of me!) could be multiply instantiated across a host of different biological or artificial bodies, even at a single moment. What *I* am, then, on this view, is a kind of subjective pattern or concatenation of such patterns, rather than a single spatiotemporally located object.

Here’s an example that might make the view seem (marginally!) more plausible. Thinking back to the one hundred simulations scenario above, imagine that we pick one simulation at random to be hooked up to a robot body, so that it can send motor outputs to the body and receive its sensory inputs. (Note that because we’re keeping all the simulations coupled together, they’ll remain in ‘phenomenal sync’ with whichever sim we choose to be embodied as a robot). The robot wakes up, looks around, and is fascinated to learn it’s suddenly in the real world, having previously spent its life in a simulation. But now it asks us: which of the Sims am I? Am I the Sim running on the mainframe in Tokyo, or the one in London, or the one in Sao Paolo?

One natural response would be that it was identical to whichever Sim we uploaded the relevant data from. But I think this neglects the fact that all one hundred Sims are causally coupled with one another, so in a sense, we uploaded the data from all of them – we just used one specific access point to get to it. To illustrate this, note that in transferring the relevant information from our Sims to the robot, we might wish (perhaps for reasons of efficiency) to grab the data from all over the place – there’s no reason we’d have to confine ourselves to copying the data over from just one Sim. So here’s an alternate hypothesis: the robot was identical to all of them, because they were all identical to one another – there was just one conscious subject all along! (Readers familiar with Dennett’s Where Am I? may see clear parallels here.)

I find something very intuitive about the response IPD provides in this case. I realize, though, that what I’ve provided here isn’t much of an argument, and invites a slew of questions and objections. For example, even if you’re sympathetic to the reading of the example above, I haven’t established the stronger claim of IPD, which makes no reference to causal coupling. This leaves it open to say, for example, that had the simulations been qualitatively identical by coincidence (for example, via being a cluster of Boltzmann brains) rather than being causally coupled, their subjects wouldn’t have been numerically identical. We might also wonder about beings whose lives are subjectively identical up to a particular point in time, and afterwards diverge. Are they the same conscious subject up until the point of divergence, or were they distinct all along? Finally, there’s also some tricky issues concerning what it means for me to survive in this framework – if I’m a phenomenal type rather than a particular token instantiation of that type, it might seem like I could still exist in some sense even if all my token instances were destroyed (although would Star Wars still exist in some relevant sense if every copy of it was lost?).

Setting aside these worries for now, I’d like to quickly explore how the truth or falsity of IPD might actually matter – in fact, might matter a great deal! Consider a scenario in which some future utilitarian society decides that the best way to maximize happiness in the universe is by running a bunch of simulations of perfectly happy lives. Further, let’s imagine that their strategy for doing this involves simulating the same single exquisitely happy life a billion times over.

If IPD is right, then they’ve just made a terrible mistake: rather than creating a billion happy conscious subjects, they’ve just made one exquisitely happy subject with a billion (hedonically redundant) instantiations! To rectify this situation, however, all they’d need to do would be to introduce an element of variation into their Sims – some small phenomenal or psychological difference that meant that each of the billion simulations was subjectively unique. If IPD is right, this simple change would increase the happiness in the universe a billion-fold.

There are other potential interesting applications of IPD. For example, coupled with a multiverse theory, it might have the consequence that you currently inhabit multiple distinct worlds, namely all those in which there exist entities that realize subjectively and psychologically identical mental states. Similarly, it might mean that you straddle multiple non-continuous areas of space and time: if the same identical simulation is run at time t1 and time t2 a billion years apart, then IPD would suggest that a single subject cohabits both instantiations.

Anyway, while I doubt I’ve convinced anyone (yet!) of this particular crazyism of mine, I hope at least it might provide the basis for some interesting metaphysical arguments and speculations.

[Image credit: Paolo Tonon]