Scientists and engineers around the world are, with varying degrees of success, racing to replicate biology and intelligence in computers. Computational biology is already simulating the nervous systems of entire organisms. Artificial intelligence seems to be able to replicate more tasks formerly thought to be the sole preserve of man each year. Many of the results are stunning. All of this is done on digital circuits and/or Turing-Church computers (two terms that for my purposes here are interchangeable — we could also call it symbol manipulation). Expectations are clearly quite high.
What should we realistically hope for? How far can these advances actually go? If they do not culminate in “actual” artificial biology (AB) and artificial intelligence (AI), then what will they end in – what logical conclusion will they reach, what kind of wall would they run up against? What expectations do we have of “actual” AB and AI?
These are extremely challenging questions. When thinking about them, we ought to always keep in mind that minds and biology are both, as far as science knows, open-ended systems, open worlds. This in the sense that we do not know all existing facts about them (unlike classical mechanics or integer arithmetic, which we can reduce to sets of rules). For all intents, given good enough equipment, we could make an indefinite amount of observations and data recordings from any cell or mind. Conversely, we cannot, starting from scratch, construct a cell or a mind starting from pure chemical compounds. Even given godlike powers in a perfectly controlled space, we wouldn’t know what to do. We cannot record in full detail the state of a (single!) cell or a mind, we cannot make perfect copies, and we cannot configure the state of a cell or mind with full precision. This is in stark contrast to digital computation, where we can always make an indefinite number of perfect copies, and where we know the lower bound of all relevant state – we know the smallest detail that matters. We know that there’s no perceivable high-level difference between having a potential difference of 5.03 volts or 5.04 volts in our transistors on the lowest level.
(Quantum theory holds that ultimately, energy can only exist in discrete states. It seems that one consequence would be that a given volume of matter can only represent a finite amount of information. For practical purposes this does not affect our argument here, since measurement and manipulation instruments in science are very far from being accurate and effective at a quantum level. It may certainly affect our argument in theory, but who says that we will not some day discover a deeper level that can hold more information?)
In other words, we know the necessary and sufficient substrate (theoretical and hardware basis) for digital computation, but we know of no such substrate for minds or cells. Furthermore, there are reasons to think that any such substrate would lie much deeper, and at a much smaller scale, than we tend to believe. We repeatedly discover new and unexpected functions of proteins and DNA. Junk DNA, a name that has more than a hint of hubris to it, was later found to have certain crucial functions – not exactly junk, in other words.
Attempts at creating artificial minds and/or artificial biology are attempts at creating detached versions of the original phenomena. They would exist inside containers, independently of time and entropy, as long as the sufficient electrical charge or storage integrity is maintained. Their ability to affect the rest of the universe, and to be affected by it, would be very strictly limited (though not nonexistent – for example, memory errors may occur in a computer as a result of electromagnetic interference from the outside). We may call such simulations unrooted or perhaps hovering. This is the quality that allows digital circuits to preserve information reliably. Interference and noise is screened out, removed.
In attempting to answer the questions posed above, we should think about two alternative scenarios, then.
Scenario 1. It is possible to find a sufficient substrate for biology and/or minds. Beneath a certain level, no further microscopic detail is necessary in the model to replicate the full range of phenomena. Biology and minds are then reduced to a kind of software; a finite amount of information, an arrangement of matter. No doubt such a case would be comforting to many of the logical positivists at large today. But it would also have many strange consequences.
Each of us as a living organism, society around us, and every entity has a history that stretches back indefinitely far. The history of cells needs a long pre-history and evolution of large molecules to begin. A substrate, in the above sense, exists and can be practically used if and only if large parts of history are dispensable. If we could create a perfect artificial cell on some substrate (in software, say) in a relatively short time span, say an hour, or, why not, less than a year, then it means that nature took an unnecessarily long way to get to its goal. (Luckily, efficient, rational, enlightened humans have now come along and found a way to cut out all that waste!) Our shorter way to the goal would then be something that cuts out all the accidental features of history, leaving only the essential parts in place. So the practically usable substrate, which allows for shortcuts in time, then seems to imply a division between essential and accidental history of the thing we wish to simulate! (I say “practically” usable, since an impractical alternative is a working substrate that requires as much time as natural history in the “real” world. In this scenario, getting to the first cell on the substrate takes as long as it did in reality starting from, say, the beginning of the universe. Not a practical scenario, but an interesting thought experiment.) Note that if we are able to somehow run time faster in the simulation than in reality, then it would also mean that parts of history (outside the simulation) are dispensable: some time would have been wasted on unecessary processes.
Scenario 2. Such a substrate does not exist. If no history is accidental, if the roundabout historical process taken by the universe to reach the goal of, say, the first cell or first mind, is actually the only way that such things can be attained, then this scenario would be implied. This scenario is just as astounding as the first, since it implies that each of us depends fully on all of the history and circumstances that led up to this moment.
In deciding which of the two scenarios is more plausible, we should note that both biology and minds seem to be mechanisms for recording history in tremendous detail. Recording ability gives them advantages. This, I think, speaks in favour of the second scenario. The “junk DNA” problem becomes transposed to history itself (of matter, of nature, of societies, of the universe). Is there such a thing as junk history, events that are mere noise?
In writing the above, my aim has not been to discourage any existing work or research. But the two possibilities above must be considered and could point the way to the most worthwhile research goals for AI and AB. If the substrates can be found, then all is “well”, and we would need to truly grapple with the fact that we ourselves are mere patterns/arrangements of building blocks, mere software, body and mind. If the substrates can not be found, as I am inclined to think, then perhaps we should begin to think about completely new kinds of computation, which could somehow incorporate the parts that are missing from mere symbol manipulation. We should also consider much more seriously how closed-world systems, such as the world of digital information, can coexist harmoniously with what would be open-world systems, such as biology and minds. It seems that these problems are scarcely given any thought today.