  The fine-tuning of the universe for intelligent life has received a great
deal of attention in recent years, both in the philosophical and scientific
literature. The claim is that in the space of possible physical laws,
parameters and initial conditions, the set that permits the evolution of
intelligent life is very small. I present here a review of the scientific
literature, outlining cases of fine-tuning in the classic works of Carter, Carr
and Rees, and Barrow and Tipler, as well as more recent work. To sharpen the
discussion, the role of the antagonist will be played by Victor Stenger's
recent book The Fallacy of Fine-Tuning: Why the Universe is Not Designed for
Us. Stenger claims that all known fine-tuning cases can be explained without
the need for a multiverse. Many of Stenger's claims will be found to be highly
problematic. We will touch on such issues as the logical necessity of the laws
of nature; objectivity, invariance and symmetry; theoretical physics and
possible universes; entropy in cosmology; cosmic inflation and initial
conditions; galaxy formation; the cosmological constant; stars and their
formation; the properties of elementary particles and their effect on chemistry
and the macroscopic world; the origin of mass; grand unified theories; and the
dimensionality of space and time. I also provide an assessment of the
multiverse, noting the significant challenges that it must face. I do not
attempt to defend any conclusion based on the fine-tuning of the universe for
intelligent life. This paper can be viewed as a critique of Stenger's book, or
read independently.
