 According to the Aristotelian standard accepted by Marsilius, the object of scientific knowledge must be universal and necessarily true. This is not the case with individual things in the external world, since they are subject to change. Only the conclusion of a true and necessary syllogism can meet the standard. Hence, for Marsilius, the object of scientific knowledge is not anything outside the mind, but the mental proposition which refers to individual things and their qualities. More specifically, the proper object of scientific knowledge is a proposition in the form of a conclusion that has been deduced from necessary  premises.[4]