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what can i know?
We imbibe an archaic natural philosophy with our mother's milk. In the fullness of time, what with catching up on current literature and making some supplementary observations of our own, we become clearer on things. But the process is one of growth and gradual change: we do not break with the past, nor do we attain to standards of evidence and reality different in kind from the vague standards of children and laymen. Science is not a substitute for common sense, but an extension of it. The quest for knowledge is properly an effort simply to broaden and deepen the knowledge which the man in the street already enjoys, in moderation, in relation to the commonplace things around him. To disavow the very core of common sense, to require evidence for that which both the physicist and the man in the street accept as platitudinous, is no laudable perfectionism; it is a pompous confusion, a failure to observe the nice distinction between the baby and the bath water.
W. V. QUINE,
"THE SCOPE AND LANGUAGE OF SCIENCE"
"Is there such a thing as Nothing? We can say that socks are in the drawer or that nothing is. But if nothing can be in the drawer, then Nothing must exist in some way. But if so, does it occupy the same space at the same time as those things that aren't Nothing?"
ALEXANDER GEORGE: How many hands do you have? Two? Or do you have three? Your left hand, your right hand, and the nonexistent third hand that's attached to your head?
Obviously, that last "hand" shouldn't count. To say that you don't have a third hand isn't to say that you have a hand that possesses the property of nonexistence. We get ourselves into a real muddle if we take claims of nonexistence to mean that there is some object that has the property of nonexistence, for then that object must both exist (to have any properties whatsoever) and not exist, and that can't be. So when we say that no one came to the party, we mean to deny that someone came to the partynot to affirm that at least one person did (namely "no one," the "nonperson," the person with the rather antisocial property of nonexistence).
This confusion becomes unavoidable if one assumes that every noun in a language must refer to something. For if you do, when you come upon a sentence like "Nothing beats a royal flush," you'll be forced to conclude that something does after all beat a royal flush, namely Nothing. But not all nouns contribute to the meaning of sentences in the same way. In particular, some (like "nothing") don't refer to anything, while others (like "Manhattan") do.
Therefore, it's a confusion to think of Nothing as something that's jockeying with something for the same space. In any given space, either there's something or there isn't. And if there isn't anything there, if there's nothing there, that doesn't mean that there's actually something there, namely some thing called "Nothing."
"Doesn't the existence of something in one's imagination at the very least give that thing a semblance of actuality?"
ALEXANDER GEORGE: OK, so I'm now imagining the winning lottery ticket in my wallet. Let me check. [Pause.] Damn. Not even close to being a winner. In fact, there's not even a lottery ticket.
We might speak of a bucket of diamonds existing "in one's imagination." But this doesn't mean that the bucket of diamonds actually resides in some wispy way in one's mind. If anything does exist in one's mind, it's the thought of the bucket of diamonds, or perhaps an image of it. But not the bucket itself.
But we are very close to a Grand Philosophical Headache: understanding what makes that thought or that image about the thing it's about. This is especially puzzling when the thing it's about doesn't actually exist at all.
PETER LIPTON: I can imagine a mountain made of pure gold without that mountain existing, even a little bit. But it may well be that my act of imagination entails that something else must exist, namely the cause of that act.
Descartes used this line of thought for one of his arguments for the existence of God. He had an idea of God, and he thought that the idea must have a cause, and that the only possible cause in this case is God Himself. Why? Because a cause must have at least as much "reality" as its effect, and only God has as much reality as the idea of God. Not, it must be said, a very convincing argument to modern eyes: Why can't big ideas have small causes?
"Our eight-year-old son said yesterday that all things have opposites. He was discussing the matter with our daughter, who is ten, and she argued that this cannot be so. The examples our son provided were of the kind: light versus dark, day versus night, cold versus hot.
Our daughter then raised the question: What is the opposite of a banana?
What should I have answered? Is there really a duality in all things and, if so, how does it apply to the banana case?"
JYL GENTZLER: When my daughter was very young, she had a book called My First Look at Opposites (Dorling Kindersley, 1990). It taught her words such as "big" and "little," "thick" and "thin," "long" and "short," through colorful photographs of big and little dolls, thick and thin ropes, and long and short candles. Surprisingly, she picked up these concepts very quickly. I say "surprisingly" because as a matter of fact, the phenomenon of opposites is very complex. We use opposite terms when we are comparing objects and noting their differences. Often we make this comparative function explicit by adding the suffixes "-er" and "-est." But even when we don't use these suffixes, we are still implicitly making comparisons when we use these terms.
Let's take "poor" and "rich." People whom we characterize as poor within a particular context are markedly different with respect to wealth from those whom we characterize as rich within the same context. I mention the importance of context because in different contexts, and for the purposes of different comparisons, we may pick out the same person as rich and as poor. In his small village in the Andes, Juan is rich; but in comparison to Mary, who lives in Manhattan, he is poor. Mary is richer than Juan, but Mary is the poorest resident of Manhattan. Is Mary rich or poor? Well, it depends on the wealth of the person to whom one is implicitly comparing Mary. In different contexts, there are different ranges represented on the spectrum of wealth, and when you locate Mary on this range, she may fall at different ends, either at the end that we designate (for comparative purposes) as poor or at the end that we designate as rich.
So when we characterize two objects by using opposite terms, we're saying that these objects are very different from each other, in at least a certain respect, in at least a particular context. When we characterize a single object by using one of these terms, we are nonetheless making an implicit comparison: We are saying that within a particular context that we have in mind, this object would fall at one end on a range of a particular way of being.
What about "banana" then? Does this term also have an opposite in the sense in which "rich" has an opposite in "poor"? "Banana" isn't obviously a comparative term: Something isn't more or less of a banana; and, unlike the poor and the rich, bananas are correctly designated as bananas regardless of the context in which one is designating them as such. But perhaps matters are a bit more complex than this disanalogy might suggest. Surely we can compare bananas to other objects, and surely, some objects are much more similar to bananas than to other objects. Could there be a type of object that is an opposite to a banana in the sense of being most different from a banana?
I'm inclined to say that, no, a banana does not have an opposite in this sense. Notice that when we compare objects like lions and bananas, we don't compare every aspect of them at the same time. I can compare a lion and a banana with respect to size ("big" and "little") or with respect to a propensity to make noise ("noisy" and "quiet") or with respect to their opacity (both are opaque), and they count as similar in some respects and different in others. Whether I regard them as very similar or very different in these respects would depend on the context in which I was comparing them. Yes, a lion is big in comparison to a banana, but it is small in comparison to Earth. If I were comparing the size of a lion to the size of a banana, Earth, and the Solar System, I would count both the lion and banana as small; if I were to compare only them, then in the context that I am implicitly assuming, I would say that a lion is big and a banana is small. There is no object that counts as an opposite to a banana in the sense that it stands on the opposite end of the spectrum for any property that a banana has, in whichever context that one might be making the comparison.
Perhaps, though, "banana" has an opposite in the same way that "day" has the opposite "night." "Night" and "day" do indeed designate things that are commonly regarded as opposites, and these terms, like "banana," do not have any common comparative forms: It's never more or less day or night, even though the boundary between day and night is itself indefinite. Does anything serve as an opposite to "banana," as "night" serves as an opposite to "day"? I think so. "Night" and "day" are exhaustive as well as exclusiveif it's not day, then it's night. Now, the only thing that is opposite to "banana" in this sense is "not-banana"! Admittedly, "not-banana" is a word that we rarely have occasion to use, but that can't stop us from correctly claiming that you and I (and the Eiffel Tower) have something in common, namely we're all not-bananas.
"I believe that I am the only thing that really exists. How can anyone prove to me that he or she really exists?"
PETER LIPTON: Your question reminds me of the story Bertrand Russell once told about the philosopher who claimed that solipsismthe view that only you exist, or anyway that there is no reason to believe anyone else existswas obviously correct and she couldn't understand why everyone else didn't agree with her!
But there does seem to be a sense in which you cannot prove that anyone other than you exists. In that sense, it also seems that you can't prove that you existed in the past or will exist in the future. So if you have standards this high, then the most you know is the content of your current experience (e.g., that you're now perceiving something red), though even this may be saying too much.
"Do ideas exist independently of us, out there in the ether, waiting to be discovered?
For instance, did the idea of the motorcar exist, say, 1,000 years ago, before any human ever thought of it?"
JOSEPH G. MOORE: Discovered things exist independently of their discovery (think of uninhabited islands and rare species), while invented things come into existence in the very process of their invention (think of the first lightbulb). But even if the first light-bulb came into existence when Edison invented it, what about the idea of the lightbulb? Did Edison invent this at the same time, or was it, as you suggest, hanging around for eons just waiting for Edison or some other genius to stumble upon it?
It's a great question, and connected at root to venerable metaphysical puzzles that, in my view, are still unresolved. In fact, it's really the question that troubled Plato 2,400 years ago. The issue isn't so much how we use the concepts of invention and discovery (though this is interesting), but rather the unsettled status of the "ideas" that we discover/invent.
We often talk as if ideas transcend the particular, spatially and temporally located episodes of thinking in which they figure. We say: Newton and Leibniz came up with the idea of the calculus independently of each other. And in saying this we seem to hold that one and the same idea (or set of ideas) existed and was at work both when Newton entertained it and at the different time and place that Leibniz did. We further detach ideas from particular mental events when we say "Democracy is a great idea that's difficult to implement," or perhaps even "The idea of anonymous sex is more appealing than the reality." Or better yet, "No one has come up with an idea that will solve global suffering, but one must exist."
If we take our idea-talk seriously and straightforwardly, we seem committed to ideas as things that exist independently of the particular episodes of thinking that involve them. But where and when do these ideas exist? Always and everywhere? Outside of space and time? In some platonic heaven, or mysterious ether? No answer seems palatable, but without one we can't hope to understand how ideas come to figure in our thoughts and talk about them.
A similar puzzle plagues numbers: We talk as if numbers are distinct from the symbols, such as "2," and "¹," that we use to pick them out. For instance, when we erase the equation "2+5 = 7" on the blackboard, we don't destroy the number 2! And likewise, numbers are distinct from any mental ideas I might have about them: When I die, the numbers won't die with me! But then where, when, and how do numbers exist? And how do we interact with them? Our puzzle also connects to the ancient problem of universals: We seem to talk as if there are properties, such as redness, that exist independently of particular red things, such as my son's tricycle and the rose I just gave my wife (honestly). But then where, when, and how does the universal property of redness exist? And how do the tricycle and rose partake of it?
But now I've gotten long on rhetoric and short on argument. Suffice it to say that, in my view, your question is still unsettled and unsettling. Anyone who truly loves metaphysics will agree, as will anyone who truly loathes it.
"The movie The Matrix depicts a world in which we are all connected to a giant computer. This computer sends sensory signals directly to our brains, making us believe that we live in a fairly normal world.