Gregory B

Hal, Peikoff says that "All truths are a product of the logical identification of the facts of experience" ("Analytic-Synthetic" in the 1990 ed. of IOE, p. 112), and what comes from experience is empirical. Yes, Rand distinguished axiomatic concepts from the rest (otherwise, she would have no concept of "axiomatic concepts"), but it doesn't follow that they are non-empirical concepts. Also, it does not follow from the fact that there are foundational and non-foundational concepts that the former are non-empirical (and those who believe in a priori concepts could make a distinction among foundational and non-foundational a priori concepts). And if any concept were not empirical (a posteriori) it would have to be a priori, and Rand surely does not believe in a priori concepts. Yes, she and Peikoff would agree with Mill that the truths of arithmetic are derived from experience. But she would not conclude that they are therefore uncertain, as Mill apparently would. As to Quine, he alternates, sometimes within a sentence, between saying things that Rand and Peikoff would reject and saying thinks that they would agree with. For example, he does agree with them that the analytic-synthetic distinction is nonsense (although for some of the wrong reasons) and that metaphysics should not be rejected. Greg

I would say that the most direct way of dealing with Hume on an Objectivist foundation would be do argue against his claim that there are no necessary factual truths, and the best way to do this would be to consider Peikoff's article, "The Analytic-Synthetic Dichotomy". But first a brief summary of Hume reasoning and conclusion: He thinks that all necessary truths are mere relations of ideas. For example, "All triangle are 3-sided" is true because the idea of triangles contains the idea of 3-sidedness. As a consequence he concludes that necessary truths cannot be "factual"---that is, about the world (presumably because he thinks that ideas are in the mind, or created by the mind, and that if that is true the same must be true about relations of ideas, and so necessary truths are in the mind or created by the mind, and in that case they wouldn't tell us anything about reality outside the mind). So necessary truths are not factual, and so any truth that is factual is not necessary but rather is contingent. Well from this he draws various skeptical conclusions. (1) Since metaphysics is supposed to be about necessary factual truths he concludes that it is nonsense. (2) Since truths about science are obviously factual they must be contingent. (3) Since truths about causal connections (which are scientific truths) are obviously factual they must be contingent (and so the opposite is possible). (3) Since induction from the present to the future, or from the past to the present or the future, depends on causal connections between these times, and since nothing less than a necessary connection could warrant induction from one to the other, induction cannot be done. However, Peikoff knocks the foundation out from under this argument. He says that only facts about human free will choices are contingent (though he prefers to call them "man-made"); all others are necessary (though he prefers to call them "metaphysical"). Definitional truths are not the only necessary truths, since, as Peikoff says,a concept does not mean just its definition. Further, Peikoff says that definitions are not arbitrary products of convention anyway. This rebuts those who would say that causal truths are not necessary because they are not analytic and are not analytic because the concept of the effect is not contained in the concept of the cause (on the ground that a concept means only its definition and the effect cannot follow from the effect by definition, because definitional truths are arbitrary since definitions are arbitrary).

Punk defines the a posteriori as "something that has been directly empirically observed". But why "directly"? As far as I know all philosophers who write about a posteriori knowledge equate it with empirical knowledge. And even believers in the a priori believe that both of Punk's examples are a posteriori (empirical). However, it is true that many of those who believe that some knowledge must be a priori support their position by defining "empirical knowledge" too narrowly. For example, many confine to knowledge from sensation or perception, thereby excluding from introspection or reflection. Yes, Punk, the distinction goes back before Kant. As BurgerLau pointed out, it was originally a distinction between arguments. Such was the medieval usage. By the time of Hobbes (1600s), it was being applied to statements (sentences, propositions, or the like) or knowledge of them. What all empiricists, including, in the broad sense of that term, Rand, believe in is the doctrine known as "conceptual empiricism", which is the belief that all concepts are empirical. However, the doctrine known as "propositional empiricism", which is the belief that all knowledge is empirical, is much rarer. It seems to be held by J.S.Mill and Quine, and is held by Rand and Peikoff, as I understand them. Those who hold the first doctrine but not the second seem to me to be in an indefensible position: they say that all true statements contain only empirical concepts, but some true statements---namely, those derived from empirical concepts---are not known empirically. Why? Because they are conceptual truths. However, I say that they are known empirically because the concepts are empirical. I believe that Rand and Peikoff would agree with this. Believers in the a priori could object that, even if the truths allegedly known a priori, such as "All bachelors are unmarried", could be known a posteriori, they can still be known a priori as well, because no experience is needed to know them--once you understand the definition. But if you put enough information in the definition then, by this criterion, any truth could be known a priori. I should also point out, Punk, that there is another usage of "a priori", which is more like your usage. In this sense it doesn't mean non-empirical. In this sense relying on one's general background knowledge is often called "a priori", even though the knowledge was gained through experience. However, Kant repudiated this usage, or something like it. Most philosopher's who talk of a priori knowledge use Kant's concept or something close to it.