Expressions used in Everyday Spoken English in Social and Professional contexts
If you 'suppose' something, it means you think or assume that it is true or probable without any real knowledge. To 'presuppose' means to suppose something beforehand. This can mean to take something for granted or to assume a fact: "Your suggestion presupposes we have a large budget for this." It also means to request something as a necessary condition for something else to happen: "If we presuppose that all of the doctors have access to material with which to wash their hands, we can expect cross-infection to decrease by 25% using this method." This is a very formal expression usually used to talk about research, philosophical discussion, or in professional business contexts.