What is Physics?: A defence of classical theism

The modern world-view is very much shaped by the scientific revolution of the sixteenth to nineteenth centuries. However, the science behind Newtonian-based physics, and its daughters, has been shown to be wrong. Almost every philosophical assumption behind the mechanistic philosophy that inspired Galileo, Newton and their successors through to Maxwell, and even Einstein's classical theory of relativity, has been shown to be wrong by the experimental success of quantum field theory in the latter part of the twentieth and early twenty first centuries. Key philosophical principles, which underlie much of contemporary thought, such as nominalism, empiricism, determinism and the enlightenment views on causality are also undermined. The scientific revolution was accompanied by an unremitting criticism of classical philosophy. However, much of that criticism was based on the premise that physics is fundamentally mechanistic, an assumption we now know to be incorrect. So how well does that criticism measure up against today's science? The critical arguments are far weaker than they are often claimed to be. So what if we compare contemporary physics against classical philosophy? Classical philosophy is not unscathed, but it survives the encounter. Key classical concepts such as formal and final causality, potentiality and actuality, and the principle of (classical) causality have (when not misunderstood as the renaissance and early modern thinkers tended to do) direct analogues in quantum field theory. While it requires modification, and needs to be given a secure mathematical and geometrical foundation, the philosophy of the high medieval scholastics provides a far better basis for a philosophy of quantum physics than the various modern philosophies. The medieval philosophers showed rigorously that the premises behind classical philosophy logically imply classical monotheism. So how well do those arguments stand up when compared against modern physics, and how successful are the modern objections to those arguments? Again, the classical philosophers fare better than their later critics. For example, much of the modern criticism of the classical arguments attacks the form of causality used by the Greek, Islamic and medieval European philosophers. In the light of the mechanistic pre-twentieth century physics, such attacks seemed plausible, and were used to avoid the force of the medieval arguments. But quantum indeterminacy undermines the alternative enlightenment visions of causality (or visions of its absence), leaving only the classical version surviving. The conservation of four momentum, derived from the secure principle of locality at the foundation of quantum field theory, demands the classical principle of substance causality. In classical theism, God is not only an uncreatable creator of the universe, but actively sustains it at every moment. Physics is thus seen as a description of how God upholds and constantly guides matter. Scientific explanations are not a rival to theological explanations, but a part of the theological explanation. If this picture is correct, then how would our knowledge of God relate to our knowledge of physics? The rationality of God implies that nature can be described abstractly, and understood through reason, mathematics and probability. God's free will implies that it is impossible to predict the future with certainty, but only ascribe a certain likelihood to each outcome. God's transcendence of space and time and equal relationship to every particle in the universe enforces certain local symmetries on the physical description. But these are among the foundational principles used to construct quantum field theory. Thus it is possible to reason from the existence of God to the existence of a universe which closely (or identically) resembles the universe we live in. Modern thinkers have frequently claimed that science, reason and religious beliefs are in conflict. Those claims need reexamining.