Date of Award

Spring 1-1-2011

Document Type


Degree Name

Doctor of Philosophy (PhD)



First Advisor

Carol Cleland

Second Advisor

Robert Hanna

Third Advisor

John Jackson


Recent work in philosophy of biology has challenged the traditional assumption in philosophy of science that proper scientific explanations and predictions must be grounded in laws of nature that hold with necessity. Philosophical work on mechanisms in biology and cognitive science has shown that the traditional view, on its own, is too restrictive to account for scientific explanations and predictions in the complex, contingent realm of living systems. In the first part of my dissertation, I defend the view that a mechanistic approach to biology is preferable to the traditional approach, and I defend my own realist account of biological mechanisms. While most authors seem to consider the mechanistic approach in the life sciences to be a heuristic device rather than an objective description of nature, I argue that biological mechanisms are real in the same sense that planets, molecules, and life itself are real. Specifically, I argue that a biological mechanism is a structure or process that is part of and maintained by a living organism, and works to promote continuation of the ongoing living process of which the mechanism is a part. So, as long as organisms and life are real, biological mechanisms are also real. In the second part of my dissertation, I apply the mechanistic approach defended in Part One to the three process that together result in biological evolution: hereditary reproduction, generation of new variations, and natural selection. I show that the mechanistic approach helps clarify our understanding of how each process works (and does not work) on its own, and how each contributes to biological evolution. I consider whether each process, along with the physical realizers that bring it about, meet the criteria for being a biological mechanism as laid out in Part One. All three processes are often referred to as mechanisms, but I conclude that while there are biological mechanisms for achieving heredity and generation of new variations, the process of natural selection does not meet the criteria for being a biological mechanism, nor does the overall process of biological evolution.