Table of Contents
Demarcation Problem
The demarcation problem is the philosophical question of what criteria, if any, reliably distinguish science from non-science - including pseudoscience, metaphysics, and other knowledge systems. The scope of the problem extends to whether any single criterion is sufficient, whether the boundary is sharp or gradual, and whether the distinction carries normative weight (e.g., policy, funding, or legal standing) beyond the descriptive. The question of what counts as a satisfactory solution is itself contested; see demarcation-problem-what-counts-as-science-debate.
Current State of Knowledge
No single criterion for demarcation commands broad acceptance. Karl Popper's falsifiability criterion - the requirement that a genuinely scientific claim be capable of being shown false by observation - dominated mid-twentieth century philosophy of science and retains widespread informal use among scientists and science communicators. However, professional philosophers of science have largely moved away from falsifiability as a complete solution, citing its susceptibility to the Duhem-Quine problem (any auxiliary hypothesis can shield a core claim from falsification) and its apparent exclusion of well-regarded sciences such as historical geology and evolutionary biology from the category of science.
Logical positivism's verification criterion, which held that meaningful statements must be verifiable in principle, enjoyed influence through the early twentieth century but was largely abandoned following sustained internal critique, particularly W.V.O. Quine's attack on the analytic-synthetic distinction and the failure to formulate a workable criterion of verification.
Imre Lakatos proposed the concept of research programmes - structured sequences of theories assessed by their progressive or degenerative character over time - as a more historically realistic alternative. Larry Laudan argued in 1983 that the demarcation problem as traditionally framed is unsolvable and that the category “pseudoscience” does no useful philosophical work, a position sometimes called the “dissolution” view. Others, including Philip Kitcher and Massimo Pigliucci, have proposed multi-criterial or family-resemblance approaches that treat science as a cluster concept rather than a natural kind defined by necessary and sufficient conditions.
The problem remains active in philosophy of science, history of science, and science studies. Its practical stakes - in courtroom battles over the teaching of intelligent design, in regulatory science, and in debates over evidence-based medicine - have kept it a topic of applied as well as theoretical interest.
Consensus Status
There is broad agreement among philosophers of science that no single necessary and sufficient criterion for demarcating science from non-science has been established. This negative consensus - the rejection of simple demarcation criteria - is independently reflected across analytic philosophy of science, history and philosophy of science, and science and technology studies. See demarcation-problem-no-simple-criterion-consensus.
No comparable consensus exists on what, if anything, should replace simple criteria, or on whether the distinction between science and pseudoscience is philosophically tractable.
Viewpoints
Falsificationism. Associated with Karl Popper, this view holds that falsifiability - the logical possibility of empirical refutation - is the hallmark of scientific claims. Science advances by bold conjecture and attempts at refutation; claims immune to falsification belong to metaphysics or ideology, not science. See demarcation-problem-falsificationism-viewpoint.
Verificationism / Logical positivism. Associated with the Vienna Circle and figures such as Rudolf Carnap and A.J. Ayer, this view held that meaningful cognitive content requires verification in principle. Scientific statements are those for which empirical evidence could in principle confirm or disconfirm them. The position has been largely abandoned in its classical form but remains influential as a background orientation. See demarcation-problem-verificationism-viewpoint.
Research programmes (Lakatos). Science is best understood not as individual hypotheses but as structured programmes with a protective belt of auxiliary hypotheses surrounding a hard core. What distinguishes science is the progressive character of a programme - generating novel, confirmed predictions - rather than the falsifiability of any single claim. See demarcation-problem-lakatosian-viewpoint.
Dissolution (Laudan). The demarcation problem is a pseudo-problem. No principled, non-arbitrary boundary separates science from non-science, and the concept of pseudoscience is philosophically incoherent. Practical questions about reliability, rigor, and evidence should be addressed directly rather than through the science/non-science distinction. See demarcation-problem-dissolution-viewpoint.
Multi-criterial / Family resemblance. Science is a cluster concept characterized by a constellation of features - testability, peer review, replication, predictive success, theoretical coherence, institutional norms - no single one of which is necessary or sufficient. Demarcation is a matter of degree rather than kind. Some proponents ground this cluster of criteria in naturalistic study of scientific practice rather than philosophical stipulation. See demarcation-problem-multicriteria-viewpoint.
Sociological / Constructivist. Associated with science studies and the sociology of scientific knowledge, this view holds that demarcation is not a purely epistemic achievement but a social one - the result of social processes, institutional practices, and professional norms. What counts as science is partly a function of how boundaries are drawn and maintained by scientists and institutions over time. See demarcation-problem-constructivist-viewpoint.
Controversies
Intelligent design and United States courts. The question of whether intelligent design constitutes science was litigated in Kitzmiller v. Dover Area School District (2005), in which the court applied a set of informal demarcation criteria to conclude it does not; philosophers of science disputed both the criteria used and the propriety of courts resolving philosophical questions. See demarcation-problem-intelligent-design-kitzmiller-controversy.
Conflict thesis. The claim that science and religion are inherently and historically in conflict has shaped how the demarcation problem is publicly framed; historians of science have extensively challenged the conflict thesis as a nineteenth-century rhetorical construction rather than an accurate historical account. See conflict-thesis-draper-white-controversy.
Related Pages
Footnotes
1. Karl R. Popper, The Logic of Scientific Discovery (London: Hutchinson, 1959). Original German edition: Logik der Forschung (Vienna: Julius Springer, 1935).
2. Rudolf Carnap, “The Elimination of Metaphysics Through Logical Analysis of Language,” trans. Arthur Pap, in A.J. Ayer, ed., Logical Positivism (New York: Free Press, 1959), 60-81.
3. W.V.O. Quine, “Two Dogmas of Empiricism,” Philosophical Review 60, no. 1 (1951): 20-43.
4. Pierre Duhem, The Aim and Structure of Physical Theory, trans. Philip P. Wiener (Princeton: Princeton University Press, 1954). Original French edition, 1906.
5. Imre Lakatos, “Falsification and the Methodology of Scientific Research Programmes,” in Imre Lakatos and Alan Musgrave, eds., Criticism and the Growth of Knowledge (Cambridge: Cambridge University Press, 1970), 91-196.
6. Larry Laudan, “The Demise of the Demarcation Problem,” in R.S. Cohen and Larry Laudan, eds., Physics, Philosophy and Psychoanalysis (Dordrecht: Reidel, 1983), 111-127.
7. Philip Kitcher, Abusing Science: The Case Against Creationism (Cambridge, MA: MIT Press, 1982).
8. Massimo Pigliucci and Maarten Boudry, eds., Philosophy of Pseudoscience: Reconsidering the Demarcation Problem (Chicago: University of Chicago Press, 2013).
9. Thomas F. Gieryn, “Boundary-Work and the Demarcation of Science from Non-Science: Strains and Interests in Professional Ideologies of Scientists,” American Sociological Review 48, no. 6 (1983): 781-795.
10. Kitzmiller v. Dover Area School District, 400 F. Supp. 2d 707 (M.D. Pa. 2005).
11. John William Draper, History of the Conflict Between Religion and Science (New York: D. Appleton, 1874); Andrew Dickson White, A History of the Warfare of Science with Theology in Christendom, 2 vols. (New York: D. Appleton, 1896).
12. John Hedley Brooke, Science and Religion: Some Historical Perspectives (Cambridge: Cambridge University Press, 1991).