Paramenides and Zeno argued that change is impossible because it is not intelligble. → Paramenides: we can only speak or think about what is but to think or speak of change requires thinking or speaking of what is not as well.
Zeno: his paradoxes show that th ides of change or motion is inconsisten Plato: the objects of knowledge must always be what they are, never something else: the unchanging, eternal Forms. Only they are truly somwthing, only they have nature or essence. Material things which are all subject to change can only be perceived
→ they all don’t think changes have an identifiable structure
Aristotle’s reply:
- At least, some things we perceive, that is at least some of the regular material objects,have essences or natures: the primary substances.
- Although their particular natures can perish (as when an animal or a plant dies), they are stable at least intwo ways
- As long as the primary substance exists, it always has the same nature even if it undergoues great number of chnages through its existence
- Even when a particular primary substance perishes, the species or kind that i belongs to (i.e., the secondary substance), does not.
Aristotle investigates Change further and defines the following terms: Nature: an inner principle of change (and rest). Physics is Aristotle’s investigation of nature.