In this website, we use a practical checklist to get a basic picture of what ​​science is and a flexible flowchart to depict how science works. For most everyday purposes, this gives us a fairly complete picture of what science is and is not. However, there is an entire field of rigorous academic study that deals specifically with what science is, how it works, and the logic through which we build scientific knowledge. This branch of philosophy is handily called the philosophy of science. Many of the ideas that we present in this website are a rough synthesis of some new and some old ideas from the philosophy of science.

Despite its straightforward name, the field is complex and remains an area of current inquiry. Philosophers of science actively study such questions as:

• What is a ​​law of nature? Are there any in non-physical sciences like biology and psychology?
• What kind of ​​data can be used to distinguish between real causes and accidental regularities?
• How much ​​evidence and what kinds of evidence do we need before we accept ​​hypotheses?
• Why do scientists continue to rely on ​​models and ​​theories which they know are at least partially inaccurate (like Newton’s physics)?

Though they might seem elementary, these questions are actually quite difficult to answer satisfactorily. Opinions on such issues vary widely within the field (and occasionally part ways with the views of scientists themselves — who mainly spend their time doing science, not analyzing it abstractly). Despite this diversity of opinion, philosophers of science can largely agree on one thing: there is no single, simple way to define science!

Though the field is highly specialized, a few touchstone ideas have made their way into the mainstream. Here’s a quick explanation of just a few concepts associated with the philosophy of science, which you might (or might not) have encountered.

• Epistemology — branch of philosophy that deals with what knowledge is, how we come to ​​accept some things as true, and how we justify that acceptance.
• Empiricism — set of philosophical approaches to building knowledge that emphasizes the importance of ​​observable evidence from the ​​natural world.
• Induction — method of reasoning in which a generalization is argued to be true based on individual examples that seem to fit with that generalization. For example, after observing that trees, bacteria, sea anemones, fruit flies, and humans have cells, one might inductively ​​infer that all organisms have cells.
• Deduction — method of reasoning in which a conclusion is logically reached from premises. For example, if we know the current relative positions of the moon, sun, and Earth, as well as exactly how these move with respect to one another, we can ​​deduce the date and location of the next solar eclipse.
• Parsimony/Occam’s razor — idea that, all other things being equal, we should prefer a simpler explanation over a more complex one.
• Demarcation problem — the problem of reliably distinguishing science from non-science. Modern philosophers of science largely agree that there is no single, simple criterion that can be used to demarcate the boundaries of science.
• Falsification — the view, associated with philosopher Karl Popper, that evidence can only be used to rule out ideas, not to support them. Popper proposed that scientific ideas can only be ​​tested through ​​falsification, never through a search for supporting evidence.
• Paradigm shifts and scientific revolutions — a view of science, associated with philosopher Thomas Kuhn, which suggests that the history of science can be divided up into times of normal science (when scientists add to, elaborate on, and work with a central, accepted scientific theory) and briefer periods of revolutionary science. Kuhn asserted that during times of revolutionary science, anomalies refuting the accepted theory have built up to such a point that the old theory is broken down and a new one is built to take its place in a so-called “paradigm shift.”

Who’s who in the philosophy of science

If you’re interested in learning more about the philosophy of science, you might want to begin your investigation with some of the big names in the field:

Aristotle (384-322 BC) — Arguably the founder of both science and philosophy of science. He wrote extensively about the topics we now call physics, astronomy, psychology, biology, and chemistry, as well as logic, mathematics, and epistemology.

Francis Bacon (1561-1626) — Promoted a scientific method in which scientists gather many ​​facts from observations and ​​experiments, and then make ​​inductive inferences about patterns in nature.

Rene Descartes (1596-1650) — Mathematician, scientist, and philosopher who promoted a scientific method that emphasized deduction from first principles. These ideas, as well as his mathematics, influenced Newton and other figures of the Scientific Revolution.

Piere Duhem (1861-1916) — Physicist and philosopher who defended an extreme form of empiricism. He argued that we cannot draw conclusions about the existence of unobservable entities conjectured by our theories such as atoms and molecules.

Carl Hempel (1905-1997) — Developed influential theories of scientific explanation and theory confirmation. He argued that a phenomenon is “explained” when we can see that it is the logical consequence of a law of nature. He championed a hypothetico-deductive account of confirmation, similar to the way we characterize “making a ​​scientific argument” in this website.

Karl Popper (1924-1994) — Argued that falsifiability is both the hallmark of scientific theories and the proper methodology for scientists to employ. He believed that scientists should always regard their theories with a skeptical eye, seeking every opportunity to try to falsify them.

Thomas Kuhn (1922-1996) — Historian and philosopher who argued that the picture of science developed by logical empiricists such as Popper didn’t resemble the history of science. Kuhn famously distinguished between normal science, where scientists solve puzzles within a particular framework or paradigm, and revolutionary science, when the paradigm gets overturned.

Paul Feyerabend (1924-1994) — A rebel within the philosophy of science. He argued that there is no scientific method or, in his words, “anything goes.” Without regard to rational guidelines, scientists do whatever they need to in order to come up with new ideas and persuade others to accept them.

Evelyn Fox Keller (1936-) — Physicist, historian, and one of the pioneers of feminist philosophy of science, exemplified in her study of Barbara McClintock and the history of genetics in the 20th century.

Elliott Sober (1948-) — Known for his work on ​​parsimony and the conceptual foundations of evolutionary biology. He is also an important contributor to the biological theory of group selection.

Nancy Cartwright (1944-) — Philosopher of physics known for her claim that the laws of physics “lie” — i.e., that the laws of physics only apply in highly idealized circumstances. She has also worked on causation, interpretations of probability and quantum mechanics, and the metaphysical foundations of modern science.