Let's (Not) Get Physical
Sure, he made contributions to our understanding of vision and to the philosophy of mathematics, but George Berkeley is best known for making one big statement: matter, he says, is just an illusion. Yes, you heard him right. Physical objects don't really exist.
But what about that tree over there, or your hand, or the wall you just walked into a few hours ago? Aren't these things just a tiny bit material? Afraid not, at least according to old George.
Think these are the ravings of some guy on a bad trip? Guess again: we're talking about Bishop George Berkeley here. Who's that, you ask? Well, not only was this guy an illustrious philosopher, he was also one of the three key figures (along with Locke and Hume) in the glorious tradition of British Empiricism. And guess what—his ideas changed the course of Western philosophy forever.
But, but, but… how can we take his central claim seriously? Well, many of Berkeley's contemporaries didn't think that we could. Dr. Samuel Johnson, for example, once famously kicked a stone and declared about Berkeley's philosophy, "I have refuted it thus" (source). Tough crowd.
Always On My Mind
Berkeley's on that already, though, particularly in his two major books, A Treatise Concerning the Principles of Human Knowledge and Three Dialogues Between Hylas and Philonous. He starts off with the standard assumption of the empiricist: all knowledge is gained through sensory experience. Sounds pretty reasonable. But wait—don't we have sensory experience of material objects all the time? How can this guy say objects don't exist?
Let's say we have an experience of this table in front of us. What do we actually encounter? Well, we see a certain color; we feel something hard and solid when we push against it; if we rap it with our knuckle, we hear a certain sound. We have various sensations, in other words, but do we ever experience matter itself?
If you answered no, then congratulations: you may have qualified for a free all-expense paid trip to… beautiful Berkeley, California. (Special restrictions may apply.) You qualify for the prize because you recognize that we directly experience only the ideas or sensations in our own minds. What we never get to, it seems, is the supposed underlying physical stuff that we imagine causes those ideas to occur.
In other words, Berkeley says that we only experience objects as they are in our minds. We don't experience the table itself because that is no more than a made up abstraction.
Now, don't worry. Berkeley doesn't say that your experiences are actually unreal. The table, the wall, even your unopened copy of Three Dialogues that you were supposed to have read for your philosophy class are—they're all actually out there. They have 100% certified, genuine existence—as immaterial entities. We go wrong only when we start imagining that they might exist as—say it all together now, Shmoopers— material things.
No Matter—Just Keepin' It Real
So the idea that there's a world out there independent from our minds is pretty much an illusion. "Esse is percipi," in Berkeley's famous (Anglicized Latin) phrase: to be is to be perceived.
But, wait a minute, if to be is to be perceived, how does Berkeley account for the fact that there is an objective world that we all experience together? Bob has his ideas, and Jane has hers, and Miley Cyrus has hers. What guarantees, when we look at this table, that we don't all see something different? Does Miley really see the same thing we do?
Here's where Berkeley gets really clever. Or really weird, depending on your perspective.
Of course, he says, your ideas of objects in the external world don't depend on you alone; the table doesn't simply disappear when you close your eyes. Instead, all such ideas exist permanently in the mind of… um, God. That's right: it's God who ensures the independence of reality, and it's God who makes sure that we're all experiencing the same world.
For Berkeley, this argument kills two birds with one stone. First, it allows him to make room for objectivity within his mind-relative viewpoint. And, second, it enables him to prove the existence of God (remember, this is Bishop Berkeley we're talking about here). If we start doubting whether there is a divine being, all we have to do is look around us. In the end, when we look at this table, or this book, or even this precious iPhone, what we're really perceiving is the mind of God Himself.
Okay, there's no doubt that Berkeley's thought is a bit wild and wacky. The weirdest thing, though, is that the more you reflect on his ideas, the more they begin to seem, well, plausible. Consider yourselves warned.