These observations point to another theme within the writings of some strict finitists which suggests that they also anticipate the way in which predicates like ‘feasible’ and ‘infeasible’ are now employed in complexity theory. For instance, while van Dantzig (1955) suggests that the feasible numbers are closed under addition and multiplication, Yessenin-Volpin (1970) explicitly states that they should not be regarded as closed under exponentiation. The possibility that exponentiation should be understood to play a role in the formulation of strict finitism itself is also suggested by the fact that the particular examples of ‘infeasible numbers’ which have been put forth by Yessenin-Volpin and others have typically employed exponential or iterated exponential notations of the forms such as \(n_1^{{n}_2}\) or \(n_1^{n_2^{n_3}}\). This in turn suggests another reply to the sorties-based argument against strict finitism.