Editing Principle of indifference (section)

===Coins===
A [[symmetry|symmetric]] coin has two sides, arbitrarily labeled ''heads'' (many coins have the head of a person portrayed on one side) and ''tails''. Assuming that the coin must land on one side or the other, the outcomes of a coin toss are mutually exclusive, exhaustive, and interchangeable. According to the principle of indifference, we assign each of the possible outcomes a probability of 1/2.

It is implicit in this analysis that the forces acting on the coin are not known with any precision. If the momentum imparted to the coin as it is launched were known with sufficient accuracy, the flight of the coin could be predicted according to the laws of mechanics. Thus the uncertainty in the outcome of a coin toss is derived (for the most part) from the uncertainty with respect to initial conditions. This point is discussed at greater length in the article on [[coin flipping#Physics|coin flipping]].