It is often taken for granted by writers who propose--and, for that matter, by writers who oppose--'justifications' of inductions, that deduction either does not need, or can readily be provided with, justification. The purpose of this paper is to argue that, contrary to this common opinion, problems analogous to those which, notoriously, arise in the attempt to justify induction, also arise in the attempt to justify deduction.

A primary purpose of argument is to increase the degree of reasonable confidence that one has in the truth of the conclusion. A question begging argument fails this purpose because it violates what W. E. Johnson called an epistemic condition of inference. Although an argument of the sort characterized by Robert Hoffman in his response (Analysis 32.2, Dec 71) to Richard Robinson (Analysis 31.4, March 71) begs the question in all circumstances, we usually understand the charge that an argument is (...) question begging with reference to the beliefs of the person, or the sort of person, to whom the argument is directed. (shrink)

[v. 1] From the Middle Ages to the Enlightenment.--v. 2. From the German Enlightenment to the age of Darwin.

If one looks to the current textbook lore for reliable taxonomic and analytical information about the petitio principii, one is met with conceptual disarray and much too much nonsense. The present writers have recently attempted to furnish the beginnings of a theoretical reconstruction of this fallacy which is at once faithful to its formidable complexity yet useful as guide for its detection and avoidance. The fact is that the petitio has had a lengthy and interesting history, and in this paper (...) we shall want to explore certain features of its development, such as it may have been. The principal origins of the concept of circular argument are to be found in Aristotle. The Aristotelian doctrine recurs with variations in the sophismata literature of the middle ages and in logic texts and manuals right up to the present day. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:Descartes's Conception of Perfect Knowledge WILLIS DONEY IN THEFIFTHMEDITATION, after presenting his a priori argument for the existence of God, Descartes compares the certainty of his conclusion with the c~rtainty of conclusions of mathematical demonstrations. In stating the view that Descartes expresses here, I shall use letters: D for the conclusion of his a priori argument, ttamely, that there is a God, and R for an example that he (...) gives of a conclusion that he has reached in mathematics, that is, the proposition that the three angles of a triangle are equal to two right angles. Concerning the certainty of D and R, he maintains in the Fifth Meditation that he is as certain of D as of "anything else that seems most certain," implying that D is for him as cea-tain as R; and he goes on to make what is clearly intended to be a stronger claim: I also observe that the certainty of other things so depends on this that without it nothing can ever be perfectly known,x This claim is repeated, by way of a conclusion, in the next to the last sentence of the Meditation: And so I clearly see that the certainty and truth of all knowledge depends on an apprehension of the true God, in such a fashion that, before I knew him, I could have no perfect knowledge of anything else.2 i AT VII, 69; HR I, 183. "AT" stands for the edition of Charles Adam and Paul Tannery, (Euvres de Descartes (Paris: L~.opold Cerf, 1897-1913); "'HR" for the English translation by Elizabeth S. Haldane and G. R. T. Ross, The Philosophical Works of Descartes (Cambridge: Cambridge University Press, 1931). In quotations I have departed from HR to avoid infeficities or inaccuracies. The Latin locution translated "perfec0y known" is perfecte sciri; in the French translation, sfauoir parfaitement is used (AT IX, 55). This is the first occurrence of this locution in the Meditations. 2 AT VII, 71; HR I, 185. The Latin locution in the last clause is perfecte scire; the F~-ench is, again, s~auoir parfaitement (AT IX, 56). In HR there is vacillation in the translation of scientia. In these passages in the Fifth Meditation, scientia and cognitio are both rendered "knowledge"; whereas, in the Replies to the Second Set of Obj~cttons, vera scientia is "true science" (AT VII, 141; HR II, 39). For scientiae certitudinem & veritatem, I have used "certainty and truth of knowledge," and "apprehension of the true God" for veri dei cognitione. [3S7] 388 HISTORY OF PHILOSOPHY In these sentences, Descartes does not limit his claims about certainty and perfect knowledge to propositions Like R, and one of his contemporaries, taking him to be asserting that, unless a person has knowledge of God's existence, he cannot be certain of anything else, raised the objection that, earlier in the Meditations, Descartes claimed to be certain of his own existence as a thinking thing prior to having proved the existence of God) In his reply, Descartes accused his critic of misreading what he had written in the Fifth Meditation. The claim that he made there was not about all propositions---about principles and evident propositions, such as ego cogito, ergo sum and sum res eogitans, as well as propositions like Rmbut specificaUy and exclusively about propositions like R.* Whether, when confronted with his critic's objection, Descartes retracted or modified a view expressed in the Meditations is a question on which sides have been taken. In my paper I have something to say about this question, but I shall be concerned primarily with a problem of interpretation that arises whether or not we take Descartes at his word; that is, whether we take the claim that he makes in the Fifth Meditation to be exclusively about propositions like R or, contrary to Descartes's reply to his critic, to be about other propositions as well. The problem arises when we try to make sense of what he says in the Fifth Meditation in support of this claim. In the first part of my paper, I shall pose the problem, pointing out that, on a very tempting and prima facie... (shrink)