What we are discussing here is the Anthropic Principle, which while it does get a bad press at times, is pretty innocuous in its Weak form, "The world is as it is because we are". (Stephen Hawking) It simply means that of all possible explanations for the state of the universe those that result in a universe unsuitable for life cannot describe our own universe.
This requirement does place certain constraints on possible cosmological and physical theories, they have to be propitious for life, because we are here debating them!
This constraint can yield, and has yielded, predictions as to limits within which any, as yet unknown, physical parameters have to lie. The nucleo-synthesis of carbon and the beryllium-carbon resonance famously predicted by Fred Hoyle being an example of one such parameter.
Think of a new theory, is it propitious for life? No? Well then abandon it as failing the empirical test. Is not then the Weak Anthropic Principle a scientific principle with predictive power? I cannot see how it is not.
Smolin indeed criticises it as not having any such predictive power. Yet as I have pointed out elsewhere, although his Cosmological Natural Selection hypothesis in itself does not refer to the existence of life, nevertheless it has resulted in a universe in which Smolin and the rest of us are alive. The CNS ‘simply’ maximises the number of black holes in any universe, but also we may consider any other theory that determines the physical constants, the fact that they may not refer to biological requirements does not itself alter the inescapable fact of our existence. We therefore may ask why should this process produce a biologically propitious universe and not otherwise?
Of course it is perfectly possible to believe that the answer to this question is a pure ‘fluke’, a “happy coincidence”, because if it were not so we would not be here to contemplate the fact, but others may choose to believe differently. Here the ‘hand of physics’ points beyond itself to the metaphysics of unobservable other universes or a Grand Design or whatever and from the point of view of the scientific method it is difficult to distinguish between these different responses. One person may be happy to look where the hand is pointing and another not, the choice is yours!