There are trivial truths and the great truths. The opposite of a trivial truth is plainly false. The opposite of a great truth is also true.

Niels Bohr, a central figure in the development of quantum theory and the Copenhagen interpretation, often reflected on how scientific understanding advances through apparent contradictions. In the early 20th century, physicists confronted phenomena (wave–particle duality, complementarity, uncertainty) that resisted classical either/or logic. Bohr used aphoristic remarks like this in lectures and conversations to contrast simple propositions—where negation is straightforwardly false—with deep insights that can admit mutually “opposed” statements depending on experimental context or level of description. The line is widely cited as capturing Bohr’s philosophical stance that mature theories may require holding complementary truths together rather than choosing one side.

Bohr distinguishes between statements that are merely correct in a narrow, unproblematic way (“trivial truths”) and statements that capture complex reality (“great truths”). Trivial truths behave like ordinary logic: if a claim is true, its opposite is false. Great truths, by contrast, point to situations where two seemingly contradictory descriptions can both be valid—because they apply under different conditions, perspectives, or levels of analysis. The remark resonates with Bohr’s idea of complementarity in quantum mechanics: light can be truly described as a wave in one experimental setup and truly described as a particle in another. More broadly, it suggests intellectual humility: deep understanding often expands the space of what can be simultaneously, though contextually, true.

1) “There are two kinds of truth: trivial truths, where the opposite is plainly absurd, and deep truths, where the opposite is also a deep truth.”
2) “The opposite of a correct statement is a false statement. But the opposite of a profound truth may well be another profound truth.”