  On the Revisionist reading, Plato’s purpose is to refute the theories of Protagoras and Heracleitus. He thinks that the absurdities those theories give rise to, come not from trying to take the theories as unrestrictedly true, but from trying to take them as true at all, even of the sensible world. Anyone who tries to take seriously the thesis that knowledge is perception has to adopt theories of knowledge and perception like Protagoras’ and Heracleitus’. But their theories are untenable. By modus tollens this shows that D1 itself is untenable. On this reading, the strategy of the discussion of D1 is to move us towards the view that sensible phenomena have to fall under the same general metaphysical theory as intelligible phenomena.