 Various forms of Finitism are based on a similar view as the one expressed by Dummett, but in which the constructions that are allowed to prove mathematical statements are required to exist not only in principle, but also in practice. Depending on the the precise implementation of the latter notion one arrives at different forms of Finitism, such as the Ultra-Intuitionism developed by Alexander Yessenin-Volpin (1970) and the Strict Finitism developed by Crispin Wright (1982).