The word "idealism," when understood as the metaphysical position "everything is ideas" rather than some kind of optimism or high goal-setting, carries a lot of baggage with it that I hope we dispelled in the episode.
To repeat: it's not solipsism, i.e. the notion that I (or my mind) is the only thing that's real, and so everything must be an idea in my mind. No, for Berkeley, other minds (and God's!) are just as real as mine.
It's also not subjectivism, in that while there are some ideas that we can change according to our whim (those of imagination, for instance), for the most part, the ideas we find ourselves with change in lawlike ways: if I move my head this way, the scenery (a set of ideas) moves the opposite way, and then I can move my head back and have more or less the original view restored. Objects don't just disappear when I close my eyes or leave the room for a second unless there was a mundane physical cause for this.
It's also not mysticism: Despite my song choice (listen to "I Am the Cosmos" here!), I am not the cosmos, nor are my ideas part of me. I gave Berkeley a lot of criticism in our discussion for not explaining how me having an idea and God having that idea before me and somehow giving it to me works, but I think Berkeley would say we shouldn't be surprised by that: most of God's creation is not amenable to observation, and all we need to understand is that a) I experience what it is to have an idea, and so for a mind in general to have an idea, all the time; that's about as clear as clear can be, and b) God must exist as objective grounding for all these ideas. I am not (according to my experience) the objective grounding of ideas, meaning that my whims or desires or evident actions are obviously not the basis of the stability and lawlike character of experience referred to above. So there is a God (or some other objective ground), and it is not me, nor are the ideas themselves God, because God is unchanging whereas ideas seem to change all the time.
It's also not relativism: God is the objective ground of these various ideas, which He relates in lawlike ways, and so, on questions of fact where two people disagree, they're likely just referring to different aspects of a thing, or rather different ideas which are normally grouped together as a thing ("The oar is bent!" "No, the oar is straight!") and so are in a sense talking about different things. In the same way that everyday utility could still allow us to say that one person is right and the other is wrong about the oar (the oar, in most circumstances, as when we measure it, comes out straight), we can say that, e.g. the blind man is wrong if he says that there's no silent cheetah hurtling at his face if the impending scratchy impact shows us that that was the case.
Randians, in particular, should really like idealism for the way that it avoids all of the above. Berkeley, like Rand, says that we have a knowing faculty that allows us to get at reality itself, and not just appearances, and that knowledge is a matter of discovering objective facts. Someone like Popper might say that a real respect for objectivity requires acknowledging skepticism and trying to become "less wrong" through attempted falsifications of hypotheses, but that would be tantamount to Kantianism: to saying that the world in-itself is ultimately unknowable. Berkeley and Rand say well, of course there are aspects of reality that will inevitably remain unknown for practical reasons, but that does nothing to impugn the validity of the objects of my immediate experience. There are of course other reasons Rand would reject Berkeley (like the God part), but he's A-OK by this standard so far.
So why does idealism remain icky? Foreign to our modern, scientific viewpoint? Something to be avoided by the philosophically sophisticated? For the one thing, it seems to violate Occam's Razor: isn't it more likely that the causes of our many sensations of a thing is just the existence, as a real, objective thing, of that thing? ... And not that the thing is just a cluster (even an objectively existing cluster) of ideas? What holds the ideas together? Well, God does, according to Berkeley. Theists often claim that God is the simplest explanation, because God is unitary, ultimately simple, but clearly this doesn't satisfy the scientific demand for simplicity, because we can't say how God gives us ideas or holds them together in clusters or makes them otherwise lawlike. We can't use this God hypothesis to predict what will happen next, though we can use the observation of orderliness to make such predictions (induction!).
So I'm interested in hearing from you folks. Do we have any idealists in the listenership? Theistic or non-theistic ones? Convince me that this loathing of the term "idealism" and everything associated with it is just a prejudice of the sort that Berkeley argues against! (i.e. the prejudice in favor of material objects, a concept he ultimately finds incoherent) I personally have much less difficulty with various forms of pragmatism that throw away the thing-in-itself merely because there's nothing useful we can say about it than I do with a view like Berkeley's that rules out skepticism seemingly by fiat.
Image note: I got this from "Lanes of Love," but don't know its original source.