Read pages 75-81 (in the 6th edition), or pages 75-81 in 5th Edition, or pages 75-81 in 3rd Edition, or pages 76-85 in 3rd Edition

Before you start on the text, I'd like you to read the following explanation of Occam's Razor:

Occam's Razor

        Ockham's Razor (spell it any way you like) is the fundamental principle of knowledge production. We cannot generate knowledge about the universe without it. There is no piece of actual knowledge of anything that exists or doesn't exist that isn't based on Ockham's razor.

        Occam's Razor is a rule. It is a set of instructions of how to figure out which explanation you should select. For instance, say we are trying to explain the fact that, when you place a very hot object near to, but not touching a very cold object, the hot object will slowly become colder, and the cold object will slowly become warmer, until the two objects are the same temperature, even if the two objects are inside a vacuum.
        
Let us say that there are several theories on offer for this phenomenon.
        Theory number one, the "Just Does" theory, holds that heat just does jump from the hotter object to to the colder object.
        Theory number two, the "Intelligent Warmer" theory, holds that an undetectable supernatural being invisibly intervenes to move heat from the hot object to the colder object.
        Theory number three, the "Kinetic" theory, holds that heat is nothing more than the vibrational movement of of the molecules and atoms that make up the objects.
        Theory number four, the "Caloric" theory, holds that heat is a fluid that can be put into an object, and which will leak out of the object in all directions just so long as there is less caloric in the surroundings than in the object itself.
        Theory number five, the "Heat Fairies" theory, holds that heat is a fluid that can be carried from one object to another by tiny beings with pretty insect wings that dip tiny little buckets into hot objects to get the heat out so they can carry it over to colder objects, where they pour the heat in.
        There are two stages to Ockham's Razor. The first stage is to discard all the theories that are clearly inadequate. What this means is that, under Occam's razor, we only consider theories that actually provide some kind of more or less reasonable explanation for the phenomena.
        Theory number one, the "Just Does" theory, is obviously inadequate. Basically, it's not even an explanation at all. In fact, it's more like a refusal to provide an explanation than anything else. Technically speaking, it shouldn't even be called a theory, because it's logically equivalent to saying, "the heat moves, and I don't know why."
        Theory number two, the "Intelligent Warmer" theory, is equally inadequate. Again, it's not even an explanation at all. Imagine that you were to ask a holder of this theory how the Intelligent Warmer moves heat from one object to another. The answer would probably be something like "he just does." Now that's hardly adequate, is it? Basically, theory number two is just theory number one with the profoundly unhelpful addition of the completely useless "Intelligent Warmer."
        Theory number three, the "Kinetic" theory, clearly fails to explain how heat gets from a hotter object to a colder object inside a vacuum. In order for the movement of one particle to affect the movement of another, those particles have to come in contact. Molecular movement cannot be transmitted across a vacuum, because there are no molecules in a vacuum to carry the movement across. I want you to notice how the failure of the Kinetic theory is different from the failures of the Just Does and the Intelligent Warmer theories. With the Kinetic theory, there is a mechanism that can be compared to the phenomena, and we can think about whether or not that mechanism could possibly make the phenomenon happen. With the other two theories, there is no mechanism, and there is nothing to think about. This is why they are not even explanations at all, and should not even really be called "theories." The only difference between them is that the Just Does theory basically refuses to give an explanation, and the Intelligent Warmer theory pretends to give an explanation, but really doesn't.
        Theory number four, the "Caloric" theory, actually has a reasonably adequate explanation for how heat gets from one object to another. If heat is a fluid, an actual stuff that can flow into and out of objects, it could flow across the vacuum. Hotter objects would spit out more caloric than colder objects, and so hotter objects would tend to get colder, and colder objects would tend to get warmer, as caloric moved back and forth between them.
        Theory number five, the "Heat Fairies" theory is just as adequate, in that it gives us a mechanism by which heat can move from one object to another through a vacuum.
        So, after applying the first stage of Occam's razor, we are left with two reasonably adequate theories. There is the caloric theory, in which heat is a fluid that moves between objects of its own accord, and the heat fairies theory, in which heat is a fluid that is carried from object to object by fairies. None of the other theories is even remotely close to adequate, because none of them explain how heat gets across a vacuum.
        The second stage of Occam's razor says that we should choose the theory that requires us to accept the existence of the fewest new entities. If a theory requires us to believe in something that we don't see anywhere else in the universe, then we should not believe in that thing unless we have absolutely no other choice. Both the caloric theory and the heat fairies theory require us to believe that heat is a fluid. We don't see this kind of fluid anywhere else, so Occam's razor says we should not accept its existence if we have any choice. But, at this point in our deliberations, we don't have any other choice. Our only two adequate theories both require that heat be a fluid. On the other hand, the heat fairies theory requires us to believe in fairies, which we also do not see anywhere else in the universe. These fairies come with a lot of unanswered questions. Where do they come from? How do they live? Why can't we see them? Where do they get the little buckets? The heat fairy theory is therefore much more complicated in terms of existence of new objects than the caloric theory. (I like to refer to this as being more "ontologically complicated.") Occam's razor can be formulated as telling us to accept only the least ontologically complicated adequate theory. Since the caloric theory is less ontologically complicated than the only other adequate theory, Occam's razor says we should accept the caloric theory, at least as far as this example is concerned.
        I like this example because it allows me to make a very important additional point about how science makes progress. We can imagine that a scientist follows the above reasoning and accepts the caloric theory, at least tentatively. In real life however, there were other situations involving heat where the caloric theory turned out not to be an adequate explanation. In real life, the caloric theory was accepted for a number of years until certain other considerations made it clear that, overall, the kinetic theory actually turned out to be a much better explanation of heat. Crucial to this was the discovery of radiation, and the idea that rapidly moving molecules can generate infrared radiation as they bang into each other in a hot object. This allowed the kinetic theory of heat to explain how heat got across a vacuum. Prior to the discovery of radiation, some physicists accepted the caloric theory, and others accepted the kinetic theory. This was entirely appropriate, because neither theory fully passed the test of Occam's razor. The caloric theory explained more things, but was more ontologically complicated. The kinetic theory was ontologically simpler, but it did not explain as much. Once radiation was discovered, the ontologically simpler theory was also shown to be equally adequate, and so it became the accepted theory.
        I would also like to note that, if no one had invented the caloric theory, it would still have been utterly bizarre for someone to offer the intelligent warmer theory as a serious competitor to the kinetic theory of heat. Suppose physicists only know about the kinetic theory, do not know about radiation, and therefore do not yet generally accept the kinetic theory of heat. If someone came along and said "I can bridge the gap between molecular movement and transmission of heat across a vacuum by theorizing that an Intelligent Warmer moves the heat across the vacuum" he would quite rightly be laughed out of physics. Even if the kinetic theory of heat is not then adequate to explain the movement of heat across a vacuum, the intelligent warming theory is not only equally inadequate, because it does not explain how the Warmer moves the heat, it is also so ontologically complicated as to be ludicrous. How did the Intelligent Warmer come into existence? How does it live? What does it eat? Where does it get the energy to move the heat?
        Finally, if radiation is discovered, and the kinetic theory becomes adequate, the intelligent warmer theory becomes a sort of mental disease. Imagine if a defender of the intelligent warming theory were to begin by saying, "the other theories cannot provide an explanation for how heat gets across a vacuum, and so the Intelligent Warmer must exist," and when confronted with the concept of radiation, to reply "I don't accept that explanation." What would you think about the mental capacity or intellectual honesty of someone who argued in that fashion? You might find yourself thinking that nobody would ever offer this kind of "argument," but unfortunately, at least one defender of Intelligent Design has offered just exactly that kind of reasoning, and indeed this style of reasoning seems to be the closest thing that Intelligent Design has to an argument.

Ptolemy and Copernicus.

        Imagine that you have never seen an astronomy book. Imagine that no one has ever told you anything about astronomy. Imagine that you don't even know that there is such a thing as astronomy. Now imagine that you go out into the open on a very clear night and look up at the sky, and that what you see with your unaided eyes is everything you know about the night sky. What would you think, and how would you try to explain all those little lights?
        Ancient astronomers had no telescopes. All they had were their eyes, and their starting point was the night sky as you can see it today in any place without light pollution. Their first method of study was simply to make note of the positions of the brightest stars relative to the positions of other bright stars. This careful observation paid immediate dividends, because they noticed right away that some bright stars did not stay in the same places relative to other bright stars, but changed relative position over time. The Greek word for wanderer was "planet," and that's what they called these wandering stars.
        Now, I want you to put yourself in the place of an ancient astronomer. You know nothing about physics. You know nothing about vacuum. You know nothing whatsoever about these little lights in the sky except what you can see with your unaided eyes. What would you think is the best explanation for what you see up there? At the time, the simplest and most obvious explanation: first offered by Anaximander, was that the Earth hung at the center of an enormous hollow sphere made of some "crystal" (transparent material) in which the stars were embedded. Pythagoras later pointed out that some of the stars moved around relative to the others. Later thinkers, such as Eudoxus, accounted for the movements of the wandering stars by assuming that each of them was carried in the wall of its own smoothly moving crystal sphere that fit neatly inside the larger sphere. Since several planets, including the Moon in particular, had complicated motions, it was assumed that they fit inside smoothly moving spheres that fit inside other smoothly moving spheres and so on until all movements were accounted for. At the end of the process, they had an elaborate model of the universe as a set of many hollow crystal spheres, each one moving in its own stately circle, and all nested together, one inside the other, around a central, unmoving Earth.
        Based on the information available at the time, this was an absolutely brilliant model of the universe. As far as anybody could tell, it explained everything. And it passed the test of Occam's razor because there was no ontologically simpler model that also explained the same facts at that time. I want to emphasize this, because it is sometimes thought that the ancients held "primitive" or irrational views of the universe before the enlightened moderns came along and corrected them. Nothing can be further from the truth. Modern people are no smarter than ancient people. The difference between modern people and ancient people is that modern people have the advantage of coming in after the ancients had already done an enormous amount of hard cognitive work which enabled the steady incremental process which led to our modern understanding of the world.
        Once Eudoxus' model was developed it could be checked against more and more careful observations. Later thinkers such as Callippus, added more intermediate spheres to make the model better fit the observations. After a while, people started to think that the model was getting a bit too complicated. A fellow called Hipparchus decided things would be simpler if, instead of all the crystal spheres fitting one inside the other around a common center, some of them were much smaller, and fitted inside the walls of other spheres. If a star was embedded in the wall of a small sphere that rotated inside the wall of a much larger sphere that also rotated, the star would follow a path that would look like a series of small loops arranged in a circle. Hipparchus called the larger circle the "deferent," and the smaller loops "epicycles." He also introduced the idea that the rest of the universe did not revolve around the center of the Earth, but around an imaginary pointhe called the "eccentric" lay near the center of the Earth. Hipparchus' system required far fewer spheres than was thought necessary for Eudoxus' model and, as far as anyone can tell, it produced more accurate results. It's true that "spheres embedded in the walls of other spheres" is a little more complicated than "spheres inside spheres inside spheres," but it isn't much more complicated, and it was certainly just as easy to visualize. Hipparchus's model was a major advance in astronomy and, although his works are now lost to us, his system was elaborated by Ptolemy, and is now known as the Ptolemaic system.
        Modern thinkers often suffer from the delusion that Copernicus was the first person to think that the sun might be the center of the universe instead of the Earth, but this is not so. A fellow called Philolaus had that idea two thousand years earlier. It was further developed by a man called Aristarchus, whom Copernicus is known to have read. (The manuscript of Copernicus's book contains reference to Aristarchus, but that reference is missing from the published edition.) Why did ancient thinkers prefer the "geocentric" (earth centered) model of Anaximander to the "heliocentric" model of Heraclides? Well, one possible answer is that they thought that the geocentric model was less ontologically complicated than the heliocentric. The heliocentric model requires people to believe that the earth moves and the sun doesn't. This idea radically contradicts every observation that could be made at the time, and so it is the kind of thing that should not be believed if there is any less radical alternative. I won't go so far as to say that the ancients were right to reject Aristarchus' model, (his arguments were pretty damn good) but that rejection was not unreasonable given both Occam's razor, and the state of knowledge at the time.
        What Copernicus did was work out a thorough mathematical treatment of the heliocentric model, and show that it easily explained certain things, such as the fact that the planets Mars, Jupiter and Saturn periodically appeared to move some distance backwards in their orbits, much more easily than the Ptolemaic model could. It's not that the Ptolemaic model could not explain these things, it's that the Ptolemaic explanation was very, very complicated, and the Copernican explanation was very simple. Unfortunately, if you just assumed that the planets moved at constant speed in circular orbits around the center of the sun, the Copernican model would not match observations very well at all. So Copernicus, like Hipparchus, included some eccentrics and epicycles in his system. For this reason, the Copernican system was not a clear winner over Ptolemy. You could make the system simple, but only at the expense of accuracy, or you could make the system accurate, but only at the expense of simplicity.
        The theories of Ptolemy and Copernicus existed side-by-side inside science for over a hundred years. It was not until Johannes Kepler had the idea that the planets might move in elliptical orbits that the Copernican system finally fit the observations well enough to be considered the clear winner over Ptolemy. Replacing circles with elipses did not increase the overall complexity of the Copernican system because, although the ellipse is a more complicated figure than the circle, using ellipses allowed astronomers to dispense with the eccentrics and epicycles that Copernicus had been forced to include in his system. Indeed, adding the notion of the elliptical orbit to the Copernican system created a model of the solar system that was both elegantly simple, and which fit observations to a very high degree of accuracy. Before Kepler, Occam's razor did not clearly support the heliocentric model because no version of the heliocentric model could satisfy both conditions of being both ontologically simpler and clearly accurate. It was only after the addition of Kepler's ellipses that the heliocentric model could meet the criteria of being the ontologically simplest theory that adequately explained the observations.

Clearly and Completely Explain And Analyze Locke's Argument Against Rationalist Epistemology.
Explain the difference between simple and complex ideas, giving examples of each kind of idea and explaining how each is different from the other. Briefly explain Occam's razor, and explain how the existance of Locke's idea about simple and complex ideas can be used with Occam's Razor as an argument against the rationalist theory of innate ideas. Say what has to be true for this argument to work, and discuss whether or not this thing actually is true or not, and what that means.

Clearly and completely explain and analyze Locke's argument against rationalist ontology.
Explain the difference between primary qualities and secondary qualities, giving examples of each kind of quality and explaining how each is different from the other. Briefly explain Occam's razor, and explain how the existance of Locke's idea about primary and secondary qualities can be used with Occam's Razor as an argument against the rationalist theories of forms and substance. Say what has to be true for this argument to work, and discuss whether or not this thing actually is true or not, and what that means.

Clearly and completely explain and analyze Ockham's Razor, and how Occam's Razor forms the basis of our undertsanding of the natural world. Explain Occam's razor and describe how it is applied. Explain the most common misconception about Occam's Razor and why it is wrong. Give a general overview of  the amount and kinds of knowledge that have been produced by use of Occam's razor, and compare it to the quantity of useful and reliable information produced by rationalist methods of producing knowledge. Finally, say which of the two ways of thinking works, explain your reasoning, and make any other comments you think fit.

Any exam answer can be enhanced by addition of any comments that occur to you. The more you think about a topic, the more likely you are to come up with something that can earn you a little more credit for your answer. I never deduct points, so it can't hurt to add your own thoughts.

Copyright © 2013 by Martin C. Young

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