Epistemology is the philosophical effort to understand the nature, limits, and sources of human knowledge. An epistemologist asks questions like “What is knowledge?” “Is it possible to have knowledge?” “How do we get knowledge?” and “Of what can we be certain?” While it isn’t obvious which of these questions comes first, philosophers have generally focused on sorting out the appropriate link between beliefs and the actual state of the world. In Plato’s phrase, “Knowledge is true judgment with an account.”2 Consider Marco’s claim that the pool may be well stocked with catchable fish of “Any kind! Any shape! Any color or size!” To say he knows—i.e., to change his “might catch” into “will catch”—requires that it’s in fact true that he’ll catch such fish and that he has good reason to believe he will. Plato’s definition of knowledge, usually restated as “justified true belief,” is still with us today. Knowledge requires that what we believe is true and that we can justify our belief that it is true. In this way, the pursuit of knowledge resembles the work of police detectives: it’s not enough to get the right man, you also must have the evidence.3
Tossing Junk into a Small Pool
If you would be a real seeker after truth, it is necessary that at
least once in your life you doubt, as far as possible, all things.
—René Descartes
Seventeenth-century philosopher René Descartes (1596–1650) asked just what can be known beyond a shadow of a doubt. He imagined a powerful, evil genius that has dedicated his considerable power to deceiving him. As Descartes put it,
I shall then suppose . . . some evil genius not less powerful than deceitful, has employed his whole energies in deceiving me; I shall consider that the heavens, the earth, colors, figures, sound, and all other external things are naught but the illusions and dreams of which this genius has availed himself in order to lay traps for my credulity.4
Such an evil genius could easily mislead us to believe five is larger than four (or vice versa); that day-old halibut smells pleasing rather than horribly (or horribly rather than pleasingly); or that halibut do (or do not) exist at all. How could anyone have much chance of sorting out the actual from the illusory when every thought we have may well be part of the evil genius’s deceit? The problem isn’t merely with figuring out what is (or is not) an illusion but with figuring out what would count as good reason to accept (or reject) the “evil genius hypothesis” itself.
Skepticism is the notion that no adequate justification for holding this or that belief exists (and so concluding that knowledge is not possible). A “global skeptic” holds that no knowledge on any subject of any sort is possible.5 To take Descartes’s example, since we can never escape the possibility that the evil genius’s mischief stands between our beliefs and the world, we can never know what is actually the case. On the other hand, “local skeptics” hold that particular methods of justification fail to properly link our beliefs to truth. Most of us are skeptics regarding reading tarot cards, tea leaves, or the lines on the palms of the hand and would rightly dismiss Marco’s claims regarding the fish-bearing capacity of McElligot’s Pool. But he tells the farmer that
This MIGHT be a pool, like I’ve read of in books,
Connected to one of those underground brooks!
An underground river that starts here and flows
Right under the pasture! And then . . . well, who knows. (Pool)
So Marco’s justification for his claiming that there might be fish in McElligott’s Pool is that he has read about underground streams that connect seemingly isolated pools to other bodies of water presumably well stocked with exotic fish.
Even if we grant that Marco’s book wasn’t written by a crank, we know that even the most authoritative volumes sometimes contain errors. This is where the local skeptic risks slipping into the global skepticism camp—since even reference texts sometimes get the facts wrong—and getting the facts wrong was good enough reason to dismiss the powers of aura readers and astrologers as sources of justification. It would seem that we are not justified in trusting any source. Unless some good reason is offered for treating information gained via astrology differently from that gained via textbooks, we risk our local skepticism turning into global skepticism.
Even if Marco’s belief regarding the possibility that there are catchable fish in McElligot’s Pool was merely wishful thinking, it is testable. That is, we could seek and likely find support for or against Marco’s claim: we might simply sit down and wait to see if Marco actually does pull a fish from the water, or we could dive in to look around, or we might drain the pool completely and see what is left behind. Such measures might satisfy us, but not Marco—he is already satisfied that there may be fish in the pool; after all, by the time the farmer arrives on the scene, Marco already has his line in the water. Assuming that Marco has no desire to waste his time and energy, he must have good reason for—that is, be able to give an account of—why he believes that there might be fish in McElligot’s Pool.
What You See Is What You Get
Oh, the sea is so full of a number of fish,
If a fellow is patient, he might get his wish! (Pool)
Empiricism is arguably the most “commonsensical” of our theories of knowledge; its strength coming from the seeming match between our sense impressions and our ability to get on in the world. Basic empirical beliefs do seem to be reliable in a way that many of our other sorts of beliefs are not; what I know about the open tin of sardines before me—the smell, the glistening dark color, the can’s cool, smooth surface—is immediate in a way that my knowledge of the migratory patterns of Pacific albacore or the primary cause of the extinction of the Caribbean monk seal is not. Light waves bounce off the sardines, which in turn trigger my retinas to transmit information through the optic nerve into my brain. In the brain this information is processed, producing information about—and eventual action toward—the tin of sardines. Successful interaction with the world based upon this information justifies the idea that there is in fact a tin of sardines before me. The question for Marco then is, “Does he have good enough reason to justify his inference that there might be fish in McElligot’s Pool?”
Empiricism holds that knowledge is acquired through our sensory experience of the world or upon introspection of those experiences. An empirical belief is one that at base is the result of direct experience of the world. So when Marco sees his fishing line bobbing in the water, he is caused to believe that his fishing line is bobbing in the water. Further beliefs not directly experienced are then inferred, such as that there is something below the water’s surface pulling at his hook. While Marco infers the possibility of fish in McElligot’s Pool from his experience with the book and (presumably) his past experience with fishing, the farmer infers that no fish are to be found because, as he says, “The pool is too small. / And, you might as well know it, / When people have junk / Here’s the place that they throw it” (Pool).
But inference is a funny thing—it can’t guarantee that the thing inferred is in fact true. Instead, an inference gains and loses strength depending upon those things from which it is inferred. It’s possible that that garbage-filled pools might be the ideal breeding ground for some fish species—a possibility that shrinks as the farmer encounters similar fishless, junk-filled small pools throughout the area. And it’s possible that Marco’s book is mistaken; a possibility that would decrease were he to find more references to underground brooks in other well-researched books. And the pool—like Marco imagines—might not be so small after all. Maybe.
As commonsensical as it is, the empiricist approach to epistemology is not without its drawbacks. At least some of these revolve around the difficulty of just how our perception generates and justifies our empirical beliefs. The empiricist holds that when we perceive a fish with a black-and-red “checkerboard belly” we are justified to believe that there in fact is a black-and-red checkerboard-bellied fish before us. This idea that our perceiving a thing to have some property just
ifies our belief that it does have that property is called “perceptual realism.” The problem for the empiricist is to explain just how the latter follows from the former.
“Direct realism” is the idea that the world is more or less just as we perceive it to be—any property perceived to be of a thing is a property of that thing: the fish does have a checkerboard-patterned stomach and that this square is red while the square next to it is black. Were direct realism the case, perceptual realism—and with it empiricism—would be hard to reject as a theory of knowledge. Unfortunately, there is at least one serious problem: how to explain our perceptual errors; say, “seeing” a mirage in the distance on a hot day. Similarly, we watch top-hatted magicians saw their lovely assistants in half and people sometimes hallucinate when extremely tired, starving, or following the ingestion of certain drugs. If the world really is how it appears to be as the direct realist claims, the world would simultaneously have and not have a pool at that distant spot on the road, magicians’ assistants would return from the dead, and pink elephants would need to be able to materialize in front of the drunk (then dematerialize before he wakes with a hangover the next day). The senses are not entirely trustworthy, so an account of knowledge based only upon sensory experience needs a way to discern between legitimate experience and hallucination and to connect veridical experiences to the things experienced.
Philosopher John Locke (1632–1704) proposed that objects have two kinds of properties: primary properties that are perceived and are actually in the object (à la direct realism) and secondary properties that also are perceived but are not in the object. These secondary properties instead have the “powers to produce various sensations in us.”6 This “two-properties” approach is known as “indirect realism.” Imagine again an open tin of sardines sitting on the table in front of you. It has a variety of grayish colors: here a pinkish blush, there almost a creamy white, and just a little over from that it seems a luminous gray. So what color are the fish in the tin? If Locke is correct, color is all in our perceiving; the delicacy before you has no color. Color, like scent and taste, are “secondary properties,” meaning that they are not inherent to the object but are brought to it by the perceiver—no nose, no scent; no eye, no color. On the other hand, some qualities of the tin of sardines really are “in” the object and so are considered “primary properties.” These properties, such as size and shape, would be the case even if no one ever perceived it. According to Locke, the tin appears to be a three-dimensional, more-or-less rectangular object about one inch tall because it really is that size.
Unfortunately for the indirect realist, if Locke’s correct, the way we perceive the world to be is not how the world really is. The tinned sardines appear to our senses with both primary and secondary properties, and so only some of what we perceive of them can be accurate. Similarly, since we don’t seem to be able to perceive the world without secondary qualities like color and taste, we can never directly perceive the world the way it really is—our tools for perception are simply not built that way. So, how do we determine which of an object’s properties are primary—that is, not mind dependent? If no properties turn out to be independent of the viewer, we cease to be realists about the world and become epistemological idealists.
What Marco Saw on Mulberry Street7
Esse est Percipi (“To be is to be perceived”).
—George Berkeley
Bishop George Berkeley (1685–1753) gave us epistemological “idealism,” the idea that the physical stuff of the world from whales to farmers, rusty teapots to Sneeden’s Hotel is wholly a matter of perception. Imagine gazing deeply into McElligot’s Pool and through the crystal-clear water, seeing: “A long twisting eel / With a lot of strange bends / And, oddly enough, / With a head on both ends!” (Pool).
Now close your eyes. There in your mind is the eel—long, striped, two-headed—just as it appeared in the depths of the pool. But wait. Isn’t the object of your experience the eel in your head, not the one in the pool? Isn’t any knowledge about the eel really knowledge derived from that image, reliant on your senses and a product of your brain? In fact, isn’t the eel in the pool unnecessary for any of your knowledge since you’re working from that mental image when you describe it as having a head on both ends? When pressed, we might even conclude that we can have no knowledge of the external world but only of our mental representations of it: in other words, our knowledge is about our “ideas.” As Berkeley puts it,
As for our senses, by them we have the knowledge only of our sensations, ideas, or those things that are immediately perceived by sense . . . but they do not inform us that things exist without the mind, . . . if we have any knowledge at all of external things, it must be by reason, inferring their existence from what is immediately perceived by sense.8
That our knowledge is not about things of the world but about our perceptions fits well with our understanding of experience: our brain doesn’t respond to something in the external world, but rather to stimuli supplied by our sense organs. And yet, most of us would likely not give up on the notion that there is in fact an external world and that we can have knowledge of it.
If with Berkeley, we take all experience to be experience of mental images, there is no right to infer a corresponding external reality. So, how is it that an idealist would explain that each time I look at the first page of McElligot’s Pool, there is always the same picture of a mustachioed farmer with suspenders and a pitchfork leaning on a fence post? I could close the book for a moment or for a week, and when I look at it again, that page will have the same picture. Similarly, when you describe what you see on that page, it will match the one that I had described. Since Berkeley denies the existence of mind-independent objects, it’s difficult to see how your mind and mine (and mine at different times) manage to have identical perceptions of what is on that page. This sort of experience of continuity suggests that the external world exists as more than just perceptions in my mind or yours.9
Despite Berkeley’s really clever argument, few (if any) people take idealism to be true. That it is “all in our heads” is a bit hard to swallow. As importantly, idealism suffers from the same very big problem as any empirical theory of knowledge: how to justify the inference from the perception of Mrs. Umbroso hanging laundry to her actually doing so? Empiricists assert that what is perceived is caused by reality, but simply saying that it is so doesn’t make it true.
Non Sense Knowledge
Cogito, ergo sum (“I think, therefore I am”).
—René Descartes
Rationalism shares empiricism’s commitment that our knowledge needs to rest upon a set of foundational beliefs but holds that at least some of our beliefs can be wholly justified by our rational intuitions. That is, we can (and do) know things without relying upon any specific sensory experience. Rationalist claims to knowledge are justified a priori,10 meaning that we can have knowledge before our interaction with any particular empirical evidence. A priori knowledge is usually contrasted with empiricism’s a posteriori knowledge11—knowledge attainable only after interaction with sense-based evidence.
Perhaps the most famous example of a priori reasoning is found later in René Descartes’s consideration of the “evil genius hypothesis.” Recall that given the genius’s power of deceit, we would not be warranted to claim knowledge of even simple things about the world, such as that grass is green or that we have bodies (or that grass and bodies exist at all). In this thought experiment, Descartes recognizes that even if he must doubt that he is embodied and that he knows the color of grass, he is undoubtedly doubting—that he is doubting could not itself be doubted. As doubting is a kind of thinking, and thinking requires a thinker, Descartes proclaims, “Cogito, ergo sum”—I am thinking, therefore I exist.12 He understands that the nature of “thinking” is such that for it to occur, a thinker is required. So, since Descartes is thinking, Descartes must exist—a conclusion that can be reasoned to without relying upon sensory experience. Similarl
y, when Marco talks about the Thing-A-Ma-Jigger, “A fish that’s so big, if you know what I mean, that he makes a whale look like a tiny sardine!” (Pool), we can know a lot of things even if we’ve never had any experience with a Thing-A-Ma-Jigger, a whale, or a sardine. For instance, we know that if they exist they are the sorts of things that can be measured; we can rank them by relative size and we understand the concept “fish,” so a Thing-A-Ma-Jigger is some sort of creature that lives in an aquatic environment. Other examples of a priori knowledge include our knowledge that 3,977 is not the largest whole number, that all points of a circle are equidistant from the center, and that the Thing-A-Ma-Jigger cannot be simultaneously purple all over and yellow all over.
Another way to draw out the distinction between rationalist and empiricist theories of knowledge is by understanding the difference between “necessary” and “contingent.” Mrs. Umbroso claims that “lungfish breathe.” This is the sort of claim the truth of which is necessary. Given the nature of what it is to be a lungfish, to not be able to breathe is to violate what it is to be a lungfish. Similarly, “all bachelors are unmarried men” and “triangles have three sides” are necessarily true, given the nature of bachelors and triangles.
Dr. Seuss and Philosophy Page 11