Historically, mathematics has often dealt with the "expansion' of previously accepted concepts and notions. In recent years, Buzaglo (The logic of concept expansion, 2002) has provided a formalisation of concept expansion based on forcing. In this paper, I briefly review Buzaglo's logic of concept expansion and I apply it to Cantor's "creation' of the transfinite. I argue that, while Buzaglo's epistemological considerations fit well into Cantor's conceptions, Buzaglo's logic of concept expansion might be unsuitable to justify the creation of the transfinite in terms of a logically rigorous derivation of concepts.