A school of thought is an approach to a discipline by a group of people, especially one that develops its own vocabulary and intellectual tradition. There are many schools of thought in the humanities and soft sciences, including historical sciences. There are fewer schools of thought in the hard sciences, but they exist there, too (e.g., Bayesianism and Frequentism in statistics).
Examples of major schools of thought:
Biology: Creationism, Evolutionism (Naturalism)
Economics: Classical, Keynesian, Marxism, Monetarism, Rational Expectations
Geology: Catastrophism, Uniformitarianism
History (historiography): Cyclical, Christian, Marxism, Historicism, Progressivism, Postmodernism
Literary Criticism: Pragmatism, Formalism, Marxism, Psychoanalysis, New Criticism, Structuralism, Deconstruction, Post-modernism, Post-Structuralism, Post-colonialism, Feminist Theory, Queer Theory, New Historicism, Cultural Studies, Reader Response
Philosophy: Idealism, Materialism/Pragmatism, Postmodernism, Realism
Psychology: Behaviorism, Cognitivism, Functionalism, Humanistic/Gestalt, Psychoanalytic, Systems psychology
Sociology: Structural Functionalism, Conflict Theory, Symbolic Interactionism, Feminist Theory
Statistics: Bayesianism, Frequentism
Theology (Christian): Orthodoxy, Catholicism, Evangelicalism, Pentecostalism.
Schools of thought can and do co-exist. As their traditions develop over decades and centuries, it can be more difficult for inter-school dialogue because their terminology and concepts are different.
It’s often not appreciated that creationism and evolutionism are schools of thought. They have their own terms, concepts, and intellectual traditions. They deal with historical events, which makes them soft sciences. And all science is still a branch of philosophy, in which schools of thought abound.
Creationism and evolutionism have been mainstream modern science at different times: creationism up to the late 19th century, evolutionism since the late 19th century. Evolutionism began development while it was a minority view in the 18th and 19th centuries. Creationism has continued development while it is a minority view. Among the best-known evolutionists are Charles Darwin, Thomas H Huxley, and Alfred R Wallace. Among the best-known creationists are Carolus Linnaeus, Gregor Mendel, and Louis Pasteur.
Creationism and evolutionism can and should be taught as two schools of thought. Teaching them in universities should be no more controversial than teaching Marxist, feminist, or post-modernist schools of thought, which have been taught in universities for years.