Peirce held that science achieves statistical probabilities, not certainties, and that spontaneity (absolute chance) is real (see Tychism on his view).

Peirce elsewhere argues (1897) that logic's presupposition of fallibilism leads at length to the view that chance and continuity are very real (tychism and synechism).

Even the catastrophism of Clarence King and others, which postulates an acceleration in evolutionary change via sudden environmental dislocations, naturally falls under the rubric of tychism.

This evolutionary aspect of tychism compels Peirce to expand Darwin's view to a cosmological level, sending its operations back to the origin of the universe under the regulative principle of his synechism.

In his theory of tychism, Peirce sought to deny the central position of the doctrine of necessity which maintains that "the state of things existing at any time, together with certain immutable laws, completely determine the state of things at every other time."