Philosophy of Science

What it asks

Science does not simply accumulate facts. It selects what to look at, decides what counts as evidence, discards theories that once seemed secure, and keeps others despite awkward results. Philosophy of science asks what governs those choices — whether there is a method underneath them, and whether the theories that survive are true or merely useful.

The question has practical weight. Courts, parliaments and school boards need a line between science and everything dressed as it, and the branch has been asked for that line repeatedly.

The recurring problems

Demarcation. What separates science from pseudo-science? Popper's answer — that a scientific claim must forbid something, so that an observation could refute it — is the most famous proposal and is now generally thought too simple, since real theories are defended against refuting evidence all the time, sometimes rightly.

Induction. No number of confirming instances entails the next one. Hume's problem is not solved; science proceeds anyway, and explaining why that is reasonable rather than lucky is a live task.

Underdetermination. Any body of evidence is compatible with more than one theory. If the data cannot pick a winner, something else must, and identifying that something is uncomfortable.

Realism. Do electrons exist, or is talk of them a way of organising measurements? The strongest argument for realism is that the success of science would otherwise be a miracle. The strongest argument against is that past theories were successful and are now thought false.

How it developed

Reflection on scientific method is old, but the branch takes shape in the 1920s and 1930s with the Vienna Circle, whose logical positivism attempted to reduce meaningful claims to those verifiable by observation. Popper, close to that circle but never of it, replaced verification with falsification.

The decisive break came in 1962. Thomas Kuhn's The Structure of Scientific Revolutions described science as long periods of ordinary puzzle-solving punctuated by upheavals in which the standards themselves change — which made the question of scientific rationality historical rather than logical, and made the book one of the most cited of the century.

What followed was a contest over how much of Kuhn to accept. Lakatos tried to keep rationality by shifting the unit of appraisal from theory to research programme. Feyerabend argued that no methodological rule has gone unbroken by a successful scientist, and that this is a good thing.

The positions within it

Logical positivism, falsificationism, scientific realism, instrumentalism, constructive empiricism and social constructionism are treated as schools rather than branches, and appear in that section. The division that organises current work is realism against its alternatives.

Where it stands now

The general question has largely given way to specific ones. Philosophers of biology argue about species and function, philosophers of physics about the interpretation of quantum mechanics, and the assumption that one account of method covers both has quietly lapsed.

Two newer pressures are reshaping the field: the replication crisis, which turned statistical practice into a philosophical problem, and the arrival of models and simulations that no one can survey in full, which raises the question of what understanding a result even means.