For many college students, deciding what subject to major in can be a struggle. But for Peter Godfrey-Smith the decision seemed obvious almost from his first days as an undergraduate at Sydney University in Australia.

“I knew when I was a first-year student that I was going to do philosophy,” he said. “There was such excitement in philosophy at that time. Philosophy departments, when they’re going well, can generate an enormous amount of intellectual energy.”

In the mid-1980s (Godfrey-Smith earned his bachelor’s degree in 1987), Sydney University had a stellar philosophy department that drew many of the brightest, most talented students into its orbit.

That undergraduate experience set Godfrey-Smith on a path of intellectual discovery that he pursues to this day, one that focuses on the philosophy of mind and the philosophical foundations of evolution theory. Since January 2006 Godfrey-Smith has been doing his thinking and teaching as a tenured professor in the Harvard Philosophy Department.

“The philosophy of mind was one of the most exciting areas at Sydney University in the 1980s. There was also a lot of interest in naturalism, which suggested that philosophy should be informed by the sciences. One way of making this approach work is by looking at the consequences of evolutionary theory.”

Working with Kim Sterelny, one of his philosophy professors at Sydney University, Godfrey-Smith began to realize that evolutionary theory was extremely interesting in its own right. He continued to explore the subject at the University of California, San Diego, where he earned a Ph.D. in 1991. His dissertation, “Teleonomy and the Philosophy of Mind,” took an evolutionary approach to the problem of how the mind works.

Godfrey-Smith is currently working on a book in which he will attempt to provide a philosophical foundation for evolutionary theory.

“There have been many attempts to do this in the past, but my treatment will incorporate some recent insights from the philosophy of science concerning the role of idealization or model building.”

Godfrey-Smith sees Darwinian theory as having two basic core ideas. One is the notion that all organisms are intrinsically related to each other through a branching process, represented by the “tree of life.” The other is the idea of natural selection, that variations within a population and the reproductive advantage these variations confer on certain organisms will, over time, result in biological diversity.

Godfrey-Smith is particularly interested in the second of these ideas, the way the elements of variation, inheritance, and reproductive output give rise to the enormous complexity of life. He hopes to describe this mechanism in the most general way possible, without reference to gene theory, which, he believes, is not essential to the evolutionary process itself.

“What I want to do is really unpack the relationship between these three simple ingredients [variation, inheritance, reproductive output], to understand exactly what kind of machine it is that produces evolution.”

Godfrey-Smith is currently testing out these ideas in a seminar on the foundations of evolutionary theory that he is co-teaching with David Haig, the George Putnam Professor of Organismic and Evolutionary Biology.

Another of Godfrey-Smith’s interests is pragmatism, the school of philosophy founded by a group of American thinkers in the late 19th and early 20th centuries, who were among the first philosophers to be influenced by Charles Darwin’s writings on evolution. Godfrey-Smith is teaching a course on pragmatism this spring.

William James, Charles Peirce, and John Dewey are generally considered the most significant thinkers of the group, and Godfrey-Smith is currently working on a book about Dewey’s philosophical writings that he hopes will focus interest on some of the less prominent aspects of this thinker’s contributions.

“Dewey’s ideas on education are still taken seriously,” Godfrey-Smith said, “but there’s a general feeling that his more mainstream philosophical writings are unhelpfully obscure and that he doesn’t have much to contribute. I have exactly the opposite view.”

Godfrey-Smith admits that “Experience and Nature,” which he considers Dewey’s central work, “is a long, difficult book.” But he believes that within its 400-plus pages there are “three of four really big ideas,” which he hopes to present in a more accessible way.

One of these ideas has to do with Dewey’s understanding of the mind. The classical philosophical description of how the mind works, Godfrey-Smith explained, describes how sensory events give rise to ideas or beliefs. The mind, in this model, is generally thought of as having rather tight boundaries, a self-contained system taking in information about the external world through the senses and then using that information to create theories about reality.

“Dewey, on the other hand, wants to think of the limits of the mind as far more extended,” Godfrey-Smith said. “In his version, the mind has a causal effect on the environment. It’s an agent that reconstructs the circumstances in which it finds itself.”

Godfrey-Smith believes that by adopting Dewey’s version of the mind, it is possible to overcome certain difficulties that have bedeviled modern philosophical thought.

Another of Dewey’s “big ideas” has to do with the use of idealization in science and its corresponding use in philosophy. Dewey saw that scientists regularly employ idealizations or simplifications of observed reality in order to formulate problems that they are trying to solve. These idealizations are then tested experimentally to see whether they are in fact verifiable descriptions of reality.

“Philosophers also simplify or idealize reality,” Godfrey-Smith said, “but as there is usually no possibility of empirical testing, it is much harder to ensure that idealizations will play a positive role, as opposed to a distorting one. Dewey suggested that philosophers could reconceive what they’re doing by keeping a closer eye on the pitfalls as well as the benefits of idealization.”

Godfrey-Smith has taught at Stanford and the Australian National University. He is the author of “Complexity and the Function of Mind in Nature” (1996) and “Theory and Reality: An Introduction to the Philosophy of Science” (2003).