Philosophy of Science


I'm close to completing my PhD in philosophy, and my area of specialization is philosophy of science. When I tell people this, especially scientists, I tend to get strange looks -- what is philosophy of science, exactly?

What is Philosophy?

"What is philosophy?" is one of the grand questions of the ages, right after the meaning of life. I've heard many answers, but the one I prefer is the simplest. Philosophy is the love of wisdom -- philo and sophia in the ancient Greek.

But contemporary philosophy is also an academic discipline. It comes in many flavours, including ethics, epistemology, metaphysics, history of philosophy, aesthetics, logic, political philosophy, philosophy of language, philosophy of mind, et cetera, et cetera. And there are two main styles of contemporary philosophy: continental and analytic. Although I'd like to learn more about continental philosophy, I'm firmly in the analytic camp, by training and inclination. So my area of specialization is analytic philosophy of science.

What is Philosophy of Science?

Philosophy of science came into its own as a sub-discipline in the twentieth century. It traces its roots through Kant and back to Aristotle and the pre-Socratics. But it was the Vienna Circle and the American pragmatists that shaped the emerging field.

Standard topics in any textbook on philosophy of science include the relation between theory and evidence, laws and causes, induction and confirmation, scientific realism, unity of science, explanation (my own topic of research), and more. These are topics in general philosophy of science. But I would say that the majority of research is focused on philosophical issues in particular sciences. Core topics in philosophy of physics include questions about quantum weirdness and the nature of spacetime. Core topics in philosophy of biology include the gene concept and the nature evolution. There are distinct fields of philosophy of social science, cognitive science, neuroscience, chemistry, and more, each with their specialized topics.

In the broadest terms, philosophers of science address philosophical issues in science. There are more of these than one might suspect.

Famous Philosophy of Science

Some examples are in order. Here are three bits of philosophy of science that pretty much everyone will be familiar with.

Ockham's Razor

William of Ockham is reputed to have said "entia non sunt multiplicanda praeter necessitatem" -- "entities must not be multiplied beyond necessity". I prefer Einstein's gloss: "Everything should be kept as simple as possible, but no simpler." Simplicity is said to be a virtue of a theory, and we are to prefer the simpler theory over its more complex competitors, all other things being equal. But things get murky when you ask for details about what counts as simpler, and how to balance simplicity against other theoretical virtues. Contemporary philosophers have several accounts of what simplicity means in detail, and ongoing discussions about the role simplicity has played and should play in science.


Karl Popper tried to draw a sharp distinction between genuine sciences such as physics and biology and pseudo-sciences such as astrology. One of his criteria is falsifiability. While we often talk loosely about evidence confirming a theory, Popper pointed to the problem of induction and claimed that no amount of evidence will ever truly confirm a theory (at least in the logical sense). Instead, we should look for evidence that falsifies the theory -- one counterexample is all that we need. Scientific theories are designed to be falsifiable, while in a pseudo-science like astrology counterexamples can always be reinterpreted so that the theory is preserved.

If there's one bit of philosophy of science that scientists really take to heart, it's falsifiability. I'll just say that scientific practice doesn't always fit this simple picture very well. It's not clear, for example, how falsifiable string theory is. And most philosophers these days don't believe there's a sharp demarcation to be had between science and non-science.

Paradigm Shifts

While the phrase "paradigm shift" is often thrown about, not everyone knows that it was coined by Thomas Kuhn. Kuhn's famous book The Structure of Scientific Revolutions describes science in terms of two phases: normal science and revolutionary science. Normal science takes a body of theory and core problems, a paradigm, as given, and then proceeds to solve puzzles and articulate the paradigm in greater depth. Revolutionary science occurs when a paradigm breaks down, and scientists are looking to establish a new one. Kuhn claims that the battle between paradigms is largely political. And he claims that paradigms are often incommensurable: it takes a difficult mental leap to jump from one paradigm to another.

The field of philosophy of science changed significantly after Kuhn. The dominant logical empiricist tradition gave way to a wider variety of approaches better informed by the history and practice of science. So Kuhn marks a shift, but perhaps not a paradigm shift. The debate continues over the nature, the role, and even the existence of scientific paradigms.

Contemporary Philosophy of Science

So what have philosophers of science been doing lately? I'll pick a few examples from my area. I think that Jim Woodward's manipulability account of causation is a good foundation for understanding causation, and a step toward a good general account of explanation in science. The literature on mechanisms is getting at some important explanatory practices in biology and neuroscience. There's also good work being done on the role of abstraction and idealization in science.

Since this question comes up a lot in conversations I have with scientists, I'd like to have a more complete and compelling answer. I'll keep working on it.


So how is philosophy of science related to science? And what do philosophers of science have to say to scientists?

Metholodological naturalism is the vague but popular view that the goals and methods of philosophy are continuous with the methods of science. Despite their differences, there is some sort of spectrum on which philosophy and science both fit. I think it's certainly true that scientists often practice philosophy of science. Einstein's thinking about spacetime or Dawkins writing on genes are two examples of scientists tackling thorny conceptual issues with methods that philosophers use.

Sometimes philosophical approaches to scientific problems are fasionable in science, and sometimes they aren't. Lee Smolin makes this point about physics, contrasting the philosophical tendencies of Einstein and Heisenberg's generation with the hard-headed pragmatism of Feynman and Gell-mann's.

I think that philosophers of science are more closely engaged with the practice of science than they used to be, and more likely to point to specific, detailed cases before drawing generalizations about scientific practice. But for many years we've done a poor job of engaging with scientists themselves, explaining our interests to them, helping with the problems they're interested in, and building productive interdisciplinary relationships. I do see it happening, and it almost invariably leads to better philosophy and better science.

That, at least, is how I understand philosophy of science, and how I try to go about my own research.