William O

Perhaps you would set up a program that way if A does something that you don't ever want to happen. You could think about an anti-virus program that way, albeit a bit abstractly. "Infected -> not infected."

I haven't seen it used for anything productive by philosophical standards either. When philosophers use symbolic logic it seems to obfuscate their arguments more than clarify them. The assumption is that since symbolic logic is useful in mathematics it must be useful everywhere else, which is not necessarily true.

I agree, but I want to point out how things change if we view modern logic as a set of rules that computers operate according to, instead of a set of statements about reality. In a program, you could set up a line of code such that a boolean variable A changed from true to false if it was set to true initially. Alternatively, in Java at least, you could wrap the boolean variable A in an object whose sole purpose is to set the variable back to false whenever it was set to true for some reason. Neither of these would be very useful programs, mind you, but they are at least coherent interpretations of the statement.

Okay, what practical applications does modern logic have outside of computer science (and perhaps mathematics)?

I'm a computer science major, so I've had to do a ton of proofs in modern symbolic logic. Modern logic has legitimate applications in computer science for understanding how computer programs and circuits work, because we've built programming languages and computer hardware to operate according to this specific set of rules that we came up with. However, outside of computer science, I don't think it is useful for anything. What you're doing here is like trying to figure out how to prove the rules of chess - there is no proof and it doesn't even make sense to ask for proof, it's just what we've decided to work with.

I can't speak for the other posters here, but I personally am intimidated by this particular subject area and generally try to avoid discussing it. This is for two reasons: 1. Philosophy of space and time, which is the area of philosophy that this argument is relevant to, has been developed to the point that you have to have an advanced degree in physics to understand the contemporary debate or contribute meaningfully to it. 2. Leonard Peikoff, who apparently studied physics for years under the Objectivist physicist David Harriman, has advanced the argument you criticize in the OP. While I would never try to appeal to his authority to settle a dispute, I am impressed by a lot of the work he has done in other areas of philosophy, and I don't trust myself to evaluate his argument at my current level of knowledge. So, it looks like a strange argument to me, but I don't trust myself to advocate or criticize it, and the other posters here may feel this way as well.

Indeed.

Prostitution isn't really what I had in mind here. I don't get the impression that the people I'm talking about live by bad philosophies on a day to day basis.

I tried to give examples in the OP. I enjoy talking with other people in my major about how difficult the work is, and another person at my job sees me as a source of advice about college. These aren't philosophical values, but they are values in a more concrete, everyday sense. Is that clearer?

I'm not making any kind of revision here. It's just a special case of an Objectivist doctrine that is helpful for concretizing a rational view of friendship.

I don't think there's a conflict, it's just a qualification.

I have noticed that, while I greatly value virtues like rationality, honesty, and self discipline, in practice I sometimes tend to associate with people because they provide me with more concrete sorts of value. For example, there are people in my major, computer science, who I enjoy talking to primarily because they share my struggles. It's nice to know that other people had trouble with figuring out how a MouseActionListener object works in Java. I don't know these people outside the context of school, so I don't know what virtues they have apart from the minimum of rationality that any computer science major taking 300 level classes has to have demonstrated already, but they still provide me with value and psychological visibility. Or, again, at my job there is a college freshman who looks up to me and asks me for advice once in a while because I have been in college much longer than he has. He doesn't have any idea what my philosophical beliefs and values are, and indeed my beliefs and values are very different from his Christian beliefs and values, but I am valuable to him nonetheless because of the concrete fact that I know more about how college works than he does. I think this is an important qualification to the Objectivist doctrine that we should make friends with people because they share our philosophical beliefs and values. There are also, in addition, more superficial relationships that are genuinely valuable, and these are based on concrete, non-philosophical values that certain other people provide.

I look forward to your more substantive discussion of Rand's position on free will.

I think you're mistaken in your interpretation of Rand. Rand said "Reason does not work automatically; thinking is not a mechanical process; the connections of logic are not made by instinct. The function of your stomach, lungs or heart is automatic; the function of your mind is not." This is more consistent with libertarian free will than with determinism, because there would be no fundamental difference between the operation of the mind and the stomach on determinism. She also said "thinking is not an automatic function," which has similar implications. http://aynrandlexicon.com/lexicon/free_will.html

My reasons are the reasons Objectivists typically give. Introspection provides some support for the existence of libertarian free will, determinism implies skepticism, and determinists usually want to use terms like "rational" that are hard to account for satisfactorily on determinism.

I didn't read the OP as identifying causality with determinism initially, but now that StrictlyLogical points it out, it is a plausible interpretation of what was written in the OP. If the OP is advocating universal determinism as opposed to claiming that some specific events happen deterministically, then I retract my claim that there is nothing in the OP that a reasonable person could argue with.

I'll use your numbering. 1. Right, this is a pretty standard definition of determinism. The past, together with the laws of nature, necessitates the future under determinism. 2. This is basically a loose statement of Mill's method of difference, so it's solid. 3. This follows from the definition of a causal link. You probably don't even need to list this as an assumption. 4. This seems true, bracketing the problems omniscience involves. Frankly, I don't see any part of your post that a reasonable person could argue with.

During my time as an undergraduate philosophy major, Rand was mentioned several times. One of my ethics classes used James Rachels' The Elements of Moral Philosophy, which takes Rand seriously but presents a misrepresentation of her argument for egoism. (The professor in this class also presented mistaken interpretations of several other parts of Rand's philosophy.) Another ethics class mentioned Rand but only to assert that she was a nihilist in the sense that she did not believe in ultimate value. I also heard a student say that Ayn Rand was an example of a philosopher who was a logical positivist "if you want to call her a philosopher." So, my impression is that academic philosophers know that Rand is someone they have to address at some point when speaking to undergraduates, but they don't usually make a serious study of her work.

You have a good point here, but I think there are still significant benefits to arriving at a firm conclusion about the philosophers you study for a fully rational person. It wouldn't be that the philosopher's ideas would influence your behavior, as you note, but you might not have a strong rebuttal to the philosopher's ideas when you need it, or you might not be able to identify the philosopher's ideas in action as easily when you need to. See the Kant example I gave in the OP.

One thing we retain from studying a philosopher carefully is a general sense of what the philosopher said, as well as a general sense of what our reaction to it was. The details leave our memory after a certain period of time in most cases, but the most important points become hard coded into our consciousness in at least a general way. (For example, the details of Plato's Line analogy, which I just studied, will probably leave me in a few months or a year, but a sense of the distinctions he drew within the perceptual and conceptual levels will probably stay with me.) This makes the principle that we should base our beliefs on evidence and good reasoning even more vivid and urgent than it was already. If you aren't careful enough in your evaluation of Kant and don't arrive at a firm conclusion about him that integrates all the evidence, you may find yourself, in five years when you have forgotten all about Kant, unable to spot the error in some Kantian argument or policy. It's not that you won't have the explicit knowledge about Kant, because you would have forgotten a lot of that at some point either way, but you won't have your psycho-epistemology set up and attuned in such a way that spotting the error comes to you naturally. Moreover, your psycho-epistemology has a strong influence over what you will find interesting. For example, if you study logical positivism (without arriving at a strong evaluation of it), then you will find yourself more inclined toward ideas that are actively anti-integration. Studying something doesn't just give you more knowledge about that thing, it changes what makes sense to you, and that may lead you in a downward or upward spiral. I think the main practical application of these observations is that we should try not to leave an evil idea in our memory uncontested. If you read something dangerous, you should make sure you know a good refutation for it before letting yourself forget about it, or you might end up acting on it or uttering it in an unguarded moment.

Most people who adopt Hume's philosophy, in my experience, maintain that while we can't be certain of anything, we can have higher or lower degrees of probability with respect to our beliefs. This was not Hume's position, and Hume made an argument against this position in the Treatise. It goes like this: 1. Suppose we never have certainty about any of our beliefs, but only higher or lower degrees of probability. 2. Now, take a belief B. 3. From 1, we cannot assert B, but only that it is probable that B. 4. But the belief that it is probable that B is itself a belief. 5. Therefore, from 1, we cannot assert that it is probable that B, but only that it is probable that it is probable that B. 6. By extrapolation, B will be conditioned by an unlimited number of probabilities, each slightly lowering its probability. 7. This will lower the probability of B to a negligible probability. 8. Therefore, we don't have any reason at all to accept B. Since B stands for any belief, we have no reason to believe anything. Hume accepted the conclusion of this argument. So Hume is not the same kind of skeptic that thinks everything is more or less probable; he is a Pyrrhonian skeptic who thinks we have no reason to believe anything. We can only organize the variety of unjustified intuitions we find ourselves with into configurations that we find more or less aesthetically pleasing. The upshot is that we should just trust common sense and not try to analyze our philosophical beliefs down to the roots, because after a certain point everything turns subjective and arbitrary. Am I correct in thinking that this is similar to how you think about discursive truth? This is strongly suggested by your mention of Hume and your claim that discursive truth does not need to be objective.

This may be due to my lack of familiarity with Medieval metaphysics (and even more so with Medieval Islamic metaphysics), but I don't understand how the quote you provided for 1 is expounding the same doctrine as Rand's primacy of existence. My understanding is that the primacy of existence in Objectivism says that existence comes before consciousness and does not depend on consciousness - rather, consciousness depends on existence. The quote you provided does not mention consciousness, although it uses the phrase "primacy of existence," so I think it may be using the phrase differently than Rand did. I think you have provided fairly respectable reasons for doubting that 2 and 3 were completely original to Rand, although I think there is still room for argument about the degree to which Rand's principles were original. Regarding 2, while Aristotle's identification of substance with form is a precursor to Rand, it is also tied up with his own metaphysics, in particular his solution to the problem of universals which implies the existence of metaphysical forms contained within particular things. I think we can agree that Rand's principle that existence is identity is a significant improvement on this. 3 could be argued either way, although I think the evidence slightly tends to favor your position that Rand was aware of earlier thinkers who identified the principle. Rand had a tendency to exaggerate her own originality - for example, she claimed that the only prior philosopher she was influenced by was Aristotle, when John Locke and Adam Smith were clearly precursors as well. So, since we have no reason to think she would have mentioned Joseph if she had been aware of him, it is slightly more likely that she did not come up with the principle that causality is a corollary of identity on her own, as you say. Still, the issue is not settled by the evidence I am aware of.

The doctrine you expound here is Popper's falsificationism, which is rejected by Objectivism.

Just to be perfectly clear, I'll reiterate that I wasn't saying that certainty isn't possible in philosophy. Great question. I'll give three examples: 1. The primacy of existence. This was first identified by Rand. 2. Existence is identity. This was first identified by Rand, although Aristotle may be a precursor with his intriguing identification of substance with form. 3. Causality as a corollary of identity. This was identified by Aristotelian logicians like H. W. B. Joseph before Rand, but Rand is probably the most responsible for popularizing the notion, and there is no evidence that she was familiar with the work of these earlier logicians when she came up with the principle. I don't think there is any legitimate doubt at all about any of these principles.

I live in the southern United States, so there are a lot of Christians around, including at my job, where all of the managers and almost all of the employees are Christians of one sort or another. I have been asked what my religion is several times, and I always respond that that is a personal matter rather than lie or tell them that I'm an atheist. I do this because I don't know what their reaction would be, and I value my job too much to create any risk at all that I might be fired. I have thought about the matter and this is the most rational solution that I could come up with, so I don't consider it immoral. It certainly qualifies as hiding who I am, but I see it as unlikely that it will turn me into a Keating. This isn't exactly analogous to the OP's concern, which is about lying, but it seems like an exception to your claim that hiding who you are turns you into a Keating that is worth mentioning.