proposals on the table, we’ll see if there’s a way to synthesize them such that we preserve the strengths of each attempt while avoiding as many of their weaknesses as possible.
2.1.1 Complexity as Mereological Size
One simple measure tends to occur to almost everyone when confronted with this problem for the first time: perhaps complexity is a measure of the number of independent parts that a system has—a value that we might call “mereological size.” This accords rather well with complexity in the ordinary sense of the word: an intricate piece of clockwork is complex largely in virtue of having a massive number of interlocking parts—gears, cogs, wheels, springs, and so on—that account for its functioning. Similarly, we might think that humans are complex in virtue of having a very large number of “interlocking parts” that are responsible for our functioning in the way we do—we have a lot more genes than (say) the yeast microorganism. Something like this definition is explicitly embraced by, for example, Michael Strevens: “A complex system, then, is a system of many somewhat autonomous, but strongly interacting parts.” Similarly, Lynn Kiesling says, “Technically speaking, what is a complex system? It’s a system or arrangement of many component parts, and those parts interact. These interactions generate outcomes that you could not necessarily have predicted in advance.”
There are a few reasons to be suspicious of this proposal, though. Perhaps primarily, it will
- It’s interesting to point out that this is precisely the intuition that many proponents of the “intelligent design” explanation for biological complexity want to press on. See, canonically, Paley (1802).
- Even still, the amount of information encoded in the human genome is shockingly small by today’s storage standards: the Human Genome Project has found that there are about 2.9 billion base-pairs in the human genome. If every base-pair can be coded with two bits, this corresponds to about 691.4 megabytes of data. Moreover, Christley et. al. (2009) point out that since individual genomes vary by less than 1% from each other, they can be losslessly compressed to roughly 4 megabytes. To put that in perspective, even a relatively cheap modern smartphone has about 16 gigabytes of memory—enough to store almost 5,000 complete human genomes.
- Strevens (2003), p. 7
- Kiesling (2011)