The Fine-Tuning Argument for the Existence of God argues from the a priori colossal unlikelihood of a universe's physical constants' and natural laws' being such as to permit the development of the sort of complexity required for the evolution of life and, in particular, for the evolution of conscious beings, to a cosmic designer of some sort; and it argues further that that designer must have intentionality--the designer couldn't be some sort of cosmic universe-creating machine, it is argued, because then that machine would itself require a designer to make it produce just the right sort of universe. And then there's the issue of Boltzmann brains to deal with.
There being a multiverse composed of a vast number of universes, each with its own set of fundamental constants and natural laws, is suggested as a way of obviating the need for a designer.
What I want to point out at the outset is that the notion of a multiverse does not *refute* the fine-tuning argument, since we do not know that there is a multiverse any more than we know there is a designer; rather, the multiverse is postulated as a way of avoiding the need for a designer to explain the appearance of our being the recipients of extreme good fortune. The appearance of design remains; that appearance is simply explained in a nontheistic way.
What are the best arguments against the FTA?