For more than 400 years, physicists treated the universe like a machine, taking it apart to see how it ticks. The surprise is it turns out to have remarkably few parts: just leptons and quarks and four fundamental forces to glue them together.Lewis then goes on to discuss several interesting ways in which this fine-tuning manifests itself and follows up with this:
But those few parts are exquisitely machined. If we tinker with their settings, even slightly, the universe as we know it would cease to exist. Science now faces the question of why the universe appears to have been “fine-tuned” to allow the appearance of complex life, a question that has some potentially uncomfortable answers.
Examining the huge number of potential universes, each with their own unique laws of physics, leads to a startling conclusion: most of the universes that result from fiddling with the fundamental constants would lack physical properties needed to support complex life.But then he dashes off to talk about multiverses and grand simulations without even trying to answer the query he has raised, as if the designer hypothesis has been disposed of simply by posing the question. In fact, there are a number of ways to answer it as well as answering Lewis' apparent assumption that the question itself is an adequate refutation of the design hypothesis.
While this is a scientific article, we cannot ignore the fact that to many, the fact that the universe is finely tuned for intelligent life shows the hand of the creator who set the dials. But this answer, of course, leads to another question: who created the creator? Let’s see what alternatives science can offer.
One response is to note that the universe can be thought of as the sum of all contingent entities (a contingent entity is anything which could possibly not exist and whose existence depends upon something else. You and I are contingent, as is the earth and, indeed, the cosmos itself). That being so there must be a cause of the universe that is non-contingent otherwise the cause would be dependent upon something else and would itself be contingent and thus part of the universe. This would mean that the universe would be the cause of itself which is metaphysically absurd.
Now a cause that is non-contingent is necessary. It doesn't depend upon anything else for its existence. Thus Lewis' question, what caused the creator, is philosophically ill-conceived. The creator of all contingent things must itself be uncaused.
Moreover, the design hypothesis asserts that the universe has a sufficient cause. Once the skeptic grants that the universe has a cause, even if, in defiance of Occam's razor, he wants to suggest the possibility of an infinity of such causes, he has pretty much conceded that the design hypothesis is correct.
Anyway, here's a short video on the contingency argument as developed by 18th century philosopher and mathematician Gottfried Leibniz: P.S. There's a typo in Lewis' article that those who read it should be aware of. The article says that string theory allows for the existence of 10,500 different universes. The number should be 10^500 universes (i.e. a one with 500 zeros after it). It makes a big difference. Those interested in the fine-tuning of the universe should read the whole article as Lewis provides a good overview of the contemporary issues involved.