Randomness is a concept with somewhat disparate meanings in several fields. It also has a common meaning which has a loose connection with some of those more definite meanings.
Casually, it is typically used to denote a lack of order, or
purpose, or
cause[
citation needed]. In addition, more closely connected with the concept of
entropy, there is a casual sense of lack of predictability. Humans have used and considered the concept for a very long time.
Randomness, as defined by
Aristotle, is the situation when a choice is to be made which has no logical component by which to determine or make the choice (see
Buridan's ass). More recently, and more formally, a
random process is a repeating process whose outcomes follow no describable deterministic pattern, but follow a
probability distribution, such that the relative probability of the occurrence of each outcome can be approximated or calculated. For instance, the rolling of a six-sided die in neutral conditions may be said to produce random results in that one cannot compute before a roll what digit will be landed on, but the probability of landing on any of the six rollable digits can be calculated because of the finite cardinality of the set of possible outcomes.
The term is often used in
statistics to signify well-defined statistical properties, such as a lack of
bias or
correlation.
Monte Carlo Methods, which rely on random input, are important techniques in science, as, for instance,
computational science.
[1] Random selection is an official method to resolve
tied elections in some jurisdictions
[2] and is even an ancient method of
divination, as in
tarot, the
I Ching, and
bibliomancy. Its use in politics is very old, as office holders in Ancient Athens were chosen by lot, there being no voting.