A few listeners have pointed us at Melvyn Bragg's recent podcast on Berkeley (listen to it here). It starts off with the oft-cited anecdote about Samuel Johnson claiming to have refuted Berkeley by kicking a stone: obviously, such a stone that I can kick is not an "idea in my head." As should have been clear from our episode (and my recent post), this is an elementary misunderstanding of Berkeley.
The first 10 minutes of the podcast are all biography and discussion of how Berkeley followed Locke and and Descartes and fit into the scientific revolution/Enlightenment. At 11 min, we hear a bit about the Molyneux Problem: "whether a man who has been born blind and who has learnt to distinguish and name a globe and a cube by touch, would be able to distinguish and name these objects simply by sight, once he had been enabled to see." We hear about the bundle-theory of perceptions, which guest Michela Massimi equates to idealism. I'm not sure that these entirely coincide: You can have a metaphysical take on objects that says that these are just a bundle of properties (apple=red, juicy, solid with a particular texture, etc.) without saying that these properties are themselves perceptions, as opposed to something external to minds which is then perceived by minds.
We then get a rehearsal of the same basic arguments that we covered in the episode, but with a potentially important clarification from guest Tom Stoneham, who claims that Berkeley never actually said that "esse est percipi," i.e. did not make the general claim that the essence of all matter is that it is perceived, but that, of what we do perceive, its essence is that it is perceived. If we perceive something, its very nature is that it is an object of perception, and because those things are "all that matter to us, all that we perceive," then "that's enough" to account for what we call the real world. Stoneham presents Berkeley as a form of pragmatism: if there were something unperceived by any mind at all, it would make no practical difference; no one's going to be worried about the existence of things existing unperceived. This seems to me a particularly modern distortion of what Berkeley actually says, which is unequivocal in ruling out the thing-in-itself as not just practically useless, but as a self-contradiction.
Peter Millican (around 18 minutes in) adds the idea that Berkeley brings in God to assure the existence of things not perceived as a "parody," but this reading seemed to come right out of the passages that we read and referred to in the episode. Millican says that "there are not very strong hints" that Berkeley is using the continuity of physical objects as an argument for the existence of God, whereas this seemed blindingly evident to us in reading and discussing the text (and Massimi immediately agrees with us).
Stoneham follows up by emphasizing how on Berkeley's view (unlike Newton's view of absolute space and time existing independently of our minds), we're in direct communication with God; God directly injects our minds with these passive ideas. This seems pretty ineffective to me in satisfying our existential need for closeness with God: it doesn't make you feel any better when faced with tragedy, doesn't make you feel God's presence when you need it, and generally makes God look like a jerk for filling our heads with as much bad stuff as is often in there. Massimi brings up an extension of this charge right near the end of the podcast: If God is responsible for all of our ideas, then he's responsible for our sins as well. This charge is clearly not fair to Berkeley, as it's the essence of spirits (our mind, God's mind) to be active, i.e. causa sui (self-causing) and free, but as with all parts of Berkeley's view of the mechanics of these spirits, it's all left mysterious and unknowable. Berkeley claims he doesn't have to solve such problems, but only that his view doesn't introduce any more problems than his opponents' views: claiming, for instance, that it's physical objects that cause our perceptions as well as causing every movement of every other physical object just leads to all the metaphysical problems of free will that we're already familiar with, and Berkeley's view of spirits at least doesn't have Descartes's problems re. the causal interaction of mind and body. Berkeley sees all causality as mysterious, so solving it by pointing to a mystery is, if not actually informative, at least not so bullshitty as pretending that matters have actually been explained by pointing to the pineal gland or to hidden, occult powers within physical objects that effect other objects and minds.
At 27 minutes, Bragg shifts the conversation to talk about Berkeley vs. Newton (and Leibniz) on science, e.g. via Berkeley's essay "On Motion" (1721); this section of the podcast nicely fills in a gap our our discussion. At 31 minutes, we get some discussion of Berkeley's account that we can have a "notion" of our minds even though we don't have perceptions about our minds. This is not connected in the podcast with his argument for the existence of God, as it explicitly is in Berkeley and was in our discussion. Stoneham remarks that the book where Berkeley was really going to lay out his psychology (our knowledge of our own minds) was never written.
Finally, Bragg brings up Berkeley's final book, Siris, about tar water, and they have a chuckle about it just as we did, so we get to hear from Massimi who has apparently actually read that book, and gives us the connection between tar water and spirituality: "the subtle, imponderable substance called the ether, that was the matter of light, but also the matter of fire... and electrical phenomena." So Berkeley was writing in a tradition that was present in Newton himself; nothing in Berkeley's idealism ruled out whatever kind of metaphysically flavored science was popular in his day.
I don't think we should be surprised when silly things like this come up; in many discussions of historical science, theories that seemed reasonable at the time now seem laughable to us (phlogiston, anyone?). This is just part of the territory as we get into metaphysics proper, which is where scientists get most offended and/or scornful at the continued existence of philosophy. Kant dismissed metaphysics as largely groundless and speculative, but such speculation is a fun and important part of philosophy, even if it seems tacky and out of date relatively quickly.
Image Note: The cartoon is from a blog called "There Are Real Things."