In historical linguistics, the uniformitarian principle is the assumption that processes of language change that can be observed today also operated in the past. Peter Trudgill calls the uniformitarian principle "one of the fundamental bases of modern historical linguistics," which he characterizes, other things being equal, as the principle "that knowledge of processes that operated in the past can be inferred by observing ongoing processes in the present."[1] It is the linguistic adaptation of a widespread principle in the sciences, there usually known as uniformitarianism.