Darwin's Dangerous Idea (32 page)

world that isn't strictly implied—logically deducible by straightforward theorem-proving—by the physics and the initial configuration of cells. Some of the things in the Life world are just more marvelous and unanticipated ( by 6. See Dennett 1987b, ch. 9, for more on the theoretical implications of this trade-off in us, with our puny intellects) than others. There is a sense in which the Con-space and time.

way self-reproducing pixel-galaxy is "just" one more Life macromolecule 7. For a completely different perspective on two-dimensional physics and engineering, with a very long and complicated periodicity in its behavior.

see A. K. Dewdney's
The Plantverse
(1984 ), a vast improvement over Abbott's
Flatland
What if we set in motion a huge herd of these self-reproducers, and let (1884).

them compete for resources. And suppose they then evolved—that is, their descendants were not exact duplicates of them. Would these descendants 174 PRIMING DARWIN'S PUMP

The Laws of the Game of Life
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have a greater claim to having been designed? Perhaps, but there is no line to theory. I spoke with Conway once about the creation of the Game of Life, be drawn between merely ordered things and designed things. The engineer and he lamented the fact that explorations of the Life world were now almost starts with some
objets trouves,
found objects with properties that can be exclusively by "empirical" methods—setting up all the variations of interest harnessed in larger constructions, but the differences between a designed and on a computer and letting her rip to see what happens. Not only did this manufactured nail, a sawn plank, and a naturally occurring slab of slate are usually shield one from even the opportunity of devising a strict proof of not "principled." Seagull wings are great lifters, hemoglobin macromolecules what one found, but, he noted, people using computer simulations are are superb transporting machines, glucose molecules are nifty energy-typically insufficiently patient; they try out combinations and watch them for packets, and carbon atoms are outstanding all-purpose stickum-binders.

fifteen or twenty minutes, and if nothing of interest has happened, they The second point is that Life is an excellent illustration of the power— and abandon them, marking them as avenues already explored and found barren.

an attendant weakness—of computer simulations addressed to scientific This myopic style of exploration risks closing off important avenues of questions. It used to be that the only way to persuade oneself of very abstract research prematurely. It is an occupational hazard of all computer simulators, generalizations was to prove them rigorously from the fundamental principles and it is simply their high-tech version of the philosopher's fundamental or axioms of whatever theory one had: mathematics, physics, chemistry, foible: mistaking a failure of imagination for an insight into necessity. A economics. Earlier in this century, it was beginning to become clear that prosthetically enhanced imagination is still liable to failure, especially if it is many of the theoretical calculations one would like to make in these sciences not used with sufficient rigor.

were simply beyond human capacity—"intractable." Then the computer came But now it is time for the my main point. When Conway and his students along to provide a new way of addressing such questions: massive first set out to create a two-dimensional world in which interesting things simulations. Simulation of the weather is the example familiar to all of us would happen, they found that nothing seemed to work. It took more than a from watching television meteorologists, but computer simulation is also year for this industrious and ingenious group of intelligent searchers to find revolutionizing how science is conducted in many other fields, probably the the simple Life Physics rule in the Vast space of possible simple rules. All most important
epistemological
advance in scientific method since the the obvious variations turned out to be hopeless. To get some sense of this, invention of accurate timekeeping devices. In evolutionary theory, the new try altering the "constants" for birth and death—change the birth rule from discipline of Artificial Life has recently sprung up to provide a name and an three to four, for instance—and see what happens. The worlds these umbrella to cover a veritable Gold Rush of researchers at different levels, variations govern either freeze up solid in no time or evaporate into noth-from the submolecular to the ecological. Even among those researchers who ingness in no time. Conway and his students wanted a world in which growth have not taken up the banner of Artificial Life, however, there is general was possible, but not too explosive; in which "things"—higher-order patterns acknowledgment that most of their theoretical research on evolution—most of cells—could move, and change, but also retain their identity over time.

of the recent work discussed in this book, for instance—would have been And of course it had to be a world in which structures could "do things" of simply unthinkable without computer simulations to test (to confirm
or
interest (like eat or make tracks or repel things). Of all the imaginable two-disconfirm) the intuitions of the theoreticians. Indeed, as we have seen, the dimensional worlds, so far as Conway knows, there is only one that meets very idea of evolution as an algorithmic process could not be properly these
desiderata:
the Life world. In any event, the variations that have been formulated and evaluated until it was possible to test huge, complicated checked in subsequent years have never come close to measuring up to algorithmic models in place of the wildly oversimple models of earlier Conway's in terms of interest, simplicity, fecundity, elegance. The Life world theorists.

might indeed be the best of all possible (two-dimensional ) worlds.

Now, some scientific problems are not amenable to solution-by-Now suppose that some self-reproducing Universal Turing machines in the simulation, and others are probably only amenable to solution-by-simulation, Life world were to have a conversation with each other about the world as but in between there are problems that can in principle be addressed in two they found it, with its wonderfully simple physics—expressible in a single different ways, reminiscent of the two different ways of solving the train sentence and covering all eventualities.8 They would be committing a log-problem given to von Neumann—a "deep" way via theory, and a "shallow"

way via brute-force simulation and inspection. It would be a shame if the many undeniable attractions of simulated worlds drowned out our aspirations 8. John McCarthy has for years been exploring the theoretical question of the minimal to understand these phenomena in the deep ways of

Life-world configuration that can learn the physics of its own world, and has tried to enlist 176 PRIMING DARWIN'S PUMP

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ical howler if they argued that since they existed, die Life world, with its extrapolate a positive Darwinian alternative to the hypothesis that our laws particular physics,
had
to exist—for after all, Conway might have decided to are a gift from God. What would the Darwinian alternative have to be? That be a plumber or play bridge instead of hunting for this world. But what if there has been an evolution of worlds (in the sense of whole universes), and they deduced that their world was just too wonderful, with its elegant, Life-the world we find ourselves in is simply one among countless others that sustaining physics, to have come into existence without an Intelligent have existed through eternity. There are two quite different ways of thinking Creator? If they jumped to the conclusion that they owed their existence to about the evolution of laws, one of them stronger, more "Darwinian," than the activities of a wise Lawgiver, they'd be right! There is a God and his the other in that it involves something like natural selection.

name is Conway.

Might it be that there has been some sort of
differential reproduction
of But they would be
jumping
to a conclusion. The existence of a universe universes, with some varieties having more "offspring" than others? Hume's obeying a set of laws even as elegant as the Life law (or the laws of our own Philo toyed with this idea, as we saw in chapter 1: physics) does not logically require an intelligent Lawgiver. Notice first how the actual history of the Game of Life divided the intellectual labor in two: on And what surprise must we entertain, when we find him a stupid mechanic, the one hand there was the initial exploratory work that led to the physical who imitated others, and copied an art, which, through a long succession law promulgated by the Lawgiver, and on the other hand there was the of ages, after multiplied trials, mistakes, corrections, deliberations, and engineering work of the law-exploiters, the Artificers. These
might
have controversies, had been gradually improving? Many worlds might have happened in that temporal order—first Conway, in a stroke of inspired been botched and bungled, throughout an eternity, ere this system was genius, promulgates the physics of the Life world, and then he and his struck out: Much labour lost: Many fruitless trials made: And a slow, but students design and build the wonderful denizens of that world according to continued improvement carried on during infinite ages of world-making.

the law laid down. But in fact the two tasks were intermixed; many trial-and-

[Pt. V.]

error attempts to make things that were interesting provided the guidance for Conway's legislative search. Notice, second, that this postulated division of Hume imputes the "continued improvement" to the minimal selective bias labor illustrates a fundamental Darwinian theme from the previous chapter.

of a "stupid mechanic," but we can replace the stupid mechanic with The task of the wise God required to put this world into motion is a task of something even stupider without dissipating the lifting power: a purely discovery, not creation, a job for a Newton, not a Shakespeare. What Newton algorithmic Darwinian process of world-trying. Though Hume obviously found—and what Conway found—are eternal Platonic fixed points that didn't think this was anything but an amusing philosophical fantasy, the idea anybody else in principle could have discovered, not idiosyncratic creations has recently been developed in some detail by the physicist Lee Smolin that depend in any way on the particularities of the minds of their authors. If (1992). The basic idea is that the singularities known as black holes are in Conway had never turned his hand to designing cellular-automata worlds—if effect the birthplaces of offspring universes, in which the fundamental phys-Conway had never even existed—some other mathematician might very well ical constants would differ slightly, in random ways, from the physical con-have hit upon
exactly
the Life world that Conway gets the credit for. So, as stants in the parent universe. So, according to Smolin's hypothesis, we have we follow the Darwinian down this path, God the Artificer turns first into both differential reproduction and mutation, the two essential features of any God the
Lawgiver,
who now can be seen to merge with God the
Lawfinder.

Darwinian selection algorithm. Those universes that just happened to have God's hypothesized contribution is thereby becoming less personal—and physical constants that encouraged the development of black holes would hence more readily performable by something dogged and mindless!

ipso facto
have more offspring, which would have more offspring, and so Hume has already shown us how the argument runs, and now, bolstered by forth—that's the selection step. Note that there is no grim reaper of universes our experience with Darwinian thinking in more familiar terrain, we can in this scenario; they all live and "die" in due course, but some merely have more offspring. According to this idea, then, it is no mere interesting coincidence that we live in a universe in which there are black holes, nor is it an absolute logical necessity. It is, rather, the sort of conditional near-his friends and colleagues in this quest. I have always found the prospect of such a proof mouth-watering, but the paths to it are totally beyond me. So far as I know, nothing necessity you find in any evolutionary account. The link, Smolin claims, is substantive has yet been published on this most interesting epistemological question, but carbon, which plays a role both in the collapse of gaseous clouds (or in other I want to encourage others to address it. The same thought experiment is posed, inde-words, the birth of stars, a precursor to the birth of black holes) and, of pendently, in Stewart and Golubitsky 1992, pp. 261-62.

course, in our molecular engineering.

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Is the theory testable? Smolin offers some predictions that would, if dis-we need reproduction and selection if we are to traverse Vast spaces in non-confirmed, pretty well eliminate his idea: it should be the case that all the Vast amounts of time, but when time is no longer a limiting consideration,

"near" variations in physical constants from the values we enjoy should yield selection is no longer a requirement. In die course of eternity, you can go universes in which black holes are less probable or less frequent than in our
everywhere
in the Library of Babel or the Library of Mendel—or the Library own. In short, he thinks our universe should manifest at least a local, if not of Einstein (all possible values of all die constants of physics)—as long as global, optimum in die black-hole-making competition. The trouble is that you keep moving. (Hume imagines an "actuating force" to keep the shuffling there are too few constraints, so far as I can see, on what should count as a going, and this reminds us of Locke's argument about matter without motion,

"near" variation and why, but perhaps further elaboration on the theory will but it does not suppose diat the actuating force has any intelligence at all.) In clarify this. Needless to say, it is hard to know what to make of this idea yet, fact, if you shuffle through all the possibilities for eternity, you will pass but whatever the eventual verdict of scientists, the idea already serves to through each possible place in these Vast (but finite) spaces not just once but secure a philosophical point. Freeman Dyson and Fred Hoyle, among many an infinity of times!