Abstract

The intention of the presented paper is to establish within a certain modal semantic based on the situational ontology a description of the phenomenon of substantial change, which originally had been formulated within Aristotelian metaphysics – a theory based in reistic ontology. We understand substantial changesto be such changes whose subjects are primary substances (πρωται ουσι αι ) conceived as actually existing individual essences. The analysed changeability is of an existential character - it pertains to the existence of those substances. The formalised description of the chosen changes, constructed in part (1) of the study, takes into consideration the necessary condition for their occurrence: the disappearing and coming into being of successively becoming substances. Part (2) presents the manner in which it is possible to reformulate the obtained characteristic of substantial change in order to create a description of a particular variety of situational changes, which belong, in turn, to the intended interpretation of modal sentential logic of change LCG - a calculus in which change is a primitive concept precised with the help of two one-argument operators C and G, read respectively as: it changes that…, a change is enabled by this, that …..