Of all philosophers, Berkeley is one of the best at stunning and paralyzing the mind. Boswell (or someone) records a quip that “his philosophy is irrefutable and produces no persuasion”. This is a paradox that says more about his readers than about Berkeley – presumably nothing should be more persuasive than the irrefutable, unless we are speaking about the ravings of lunatics or the utterly stupid, and no one (Boswell included) thinks Berkeley is either of these.
Of all his works, I’m most struck by the Dialogues between Hylas and Philonous. The work is first of all a philosophical dialogue, that, is, a work of dialectic with a principal speaker of truth matched against someone articulating a secondary truth. A dialogue is not just a dramatization of a syllogism, as though we could just label all the parts said by Socrates, Job or Philonous as “the truth (according to the author)” and all the other characters as “the false”. It is amusing to hear the common complaint against the Socratic dialogues that they “reach no resolution”, as though this gave them some sort of skeptical purpose. Dialogues, unless they are hatchet jobs, are not supposed to give resolution, but simply to articulate the elements that the resolution would have to take into account.
To jump to the end (I might get to the details later) one resolution to the first dialogue would be to divide knowledge into perception and judgment, where the two are so radically distinguished that we are forced to say that there is no truth in perception. Taken in this way, the notion of what the sensible is would be radically distinguished between the sensible as perceived and the sensible according to judgment. One resolution to the second dialogue – and to my mind this is the only resolution – is to conclude that so far as knowledge is understood as a physical change, it cannot be in any way objective, where objective is understood to be of some thing that has a being independent of the mind. The objectivity of knowledge, even sensible knowledge, requires that even sensible knowledge is not formally and properly physical.
One response to this, of course, is to say that what Berkeley has Philonous say in the dialogue he himself says in the Principles. If this is true, then it seems to me that Berkeley is closer to the truth in the dialogues than in Principles. It’s not a matter of doctrines that need to be accepted or refuted anyway – refutation is a generally sterile enterprise, and it is certainly out-of-place when we are speaking of any philosopher in the canon. Our job is not so much to refute or accept doctrines as it is to find a place for all of them somewhere. Berkeley has an indispensable place as the thinker who showed us what knowledge is so far as it is a physical or entitative change in a subject.