I recently read an article refuting the infinite monkey theorem: that if you have lots of monkeys hammering away on typewriters one of them will eventually reproduce one of Shakespeare’s sonnets through pure chance alone. What the author was really refuting was the theory of evolution (some writers having used the infinite monkey theorem to back up their claims that evolution can occur by chance, and not by intelligent design. How can something so “design-like” occur by pure chance alone?)
The author explains his findings through many calculations, and eventually arrives at the fact that though possible, the chances of such a scenario is so small that by saying that something will “eventually reproduce” is so unlikely that using it as a analogy to evolution is akin to saying evolution’s not possible at all. But though the calculations are generally mathematically sound, the premise behind them are suspect. There’s been a misunderstanding on the author’s part on how evolution works.
In his example, the typing monkeys had to get all characters of Shakespeare’s sonnet right one time through — there was no room for error. Even if the monkey got 499 out of 500 of the characters right, a mistake on the last character would reset the monkey back to square one.
But evolution does not work like that. Evolution takes things one step at a time. At every step, changes that are fitter (more adaptive to survival) survive, while those less fit die off. So if we go back to the typing monkey example, after a monkey types the first character, if it is the same character as any of Shakespeare’s sonnets it survives, if it is not contained in any of Shakespeare’s sonnets it “dies” and the monkey continues on to its next random character, which is then once more matched against one of Shakespeare’s sonnets.
This process is iterated until a full Shakespearean sonnet is typed out. What role does chance play in this? Lots, as we’ll find out.
Imagine that the monkey sits down at a typewriter. It randomly hits a key and that key turns out to be the letter “W” — that’s down to chance. Does any of Shakespeare’s sonnets start with “W”? If there is, then the next character that will be most fit to survive will be the one that matches the second character of all Shakespearean sonnets that start with the letter “W”. Every other character will die off, but the first character remains because it is has adequate survival skills (e.g. the very basic survival mechanism is that it matches the first character of at least one of Shakespeare’s sonnets).
So the first character that the monkey types practically determines which sonnet will eventually be typed out, but the very first character is totally down to chance.