A counter-intuitive proposition is one that does not seem likely to be true using intuition or gut feelings.

Scientifically discovered, objective truths are often called counter-intuitive when intuition, emotions, and other cognitive processes outside of deductive rationality interpret them to be wrong. However, the subjective nature of intuition limits the objectivity of what to call counter-intuitive because what is counter-intuitive for one may be intuitive for another.

Flawed understanding of a problem may lead to counter-productive behavior with undesirable outcomes. In some such cases, counter-intuitive policies may then produce a more desirable outcome. For example, a policy of catching large fish and throwing back small ones so may be counter-productive. In response to that policy, evolutionary pressure may select for small fish. A counter-intuitive improvement may be to catch only medium sized fish, leaving the biggest free to breed, creating evolutionary pressure for fish to grow quickly through the medium size.New Scientist, July 2005

Counter-intuitive ideas in science

Many scientific ideas that are generally accepted by people today were formerly considered to be contrary to intuition and common sense.

For example, most everyday experience suggests that the Earth is flat; acutually, this view turns out to be a remarkably good approximation to the true state of affairs, which is that the Earth is a very big spheroid. Furthermore, prior to the Copernican revolution, heliocentrism, the belief that the Earth goes around the Sun, rather than vice versa, was considered to be contrary to common sense.

The Michelson-Morley experiment sought to measure the velocity of the Earth through the aether as it revolved around the Sun. The result was that it has no ether velocity at all. Relativity theory later explained the results, replacing the conventional notions of ether and separate space, time, mass, and energy with a counter-intuitive four-dimensional non-Euclidean universe.

Darwin's theory of evolution applies the same Copernican principle to the development of species, and also defies common sense in that the effects of Darwinian evolution are generally only visible over timescales considerably longer than a human life, and in the case of macroevolution, considerably longer than any timescale that can easily be imagined by human beings.

Quantum mechanics counterintuitively suggests that instead of being made out of particles, the universe is best described by complex-valued wave functions that often behave unlike particles.

At scales typical of human experience, the predictions of quantum mechanics and relativity are similar to those of common sense folk physics and of human intuition. However, experiments verify their counterintuitive predictions at more extreme scales, suggesting that they are more accurate than the theories which preceded them.

Attempts to unify these theories, such as string theory and M-theory, are seemingly even more counter-intuitive.

See also

• Common sense
• Folk physics
• Folk psychology
• Paradox

The following topics are commonly conidered to be counterintuitive:

• Wave-particle duality / photoelectric effect - is light a wave or a particle?
• Monotonicity criterion - as it affects voting systems
• Proof that 0.999... equals 1 - some people find this difficult to accept
• Squaring the circle - intuition suggests it's possible; it isn't

References