Aristotle: Necessity and Contingency

In De interpretatione 9, Aristotle argues against the fatalist view that if statements about future contingent singular events (e.g. ‘There will be a sea battle tomorrow,’ ‘There will not be a sea battle tomorrow’) are already true or false, then the events to which those statements refer will necessarily occur or necessarily not occur. Scholars have generally held that, to refute this argument, Aristotle allows that future contingent statements are exempt from either the principle of bivalence, or the law of (...) excluded middle. This paper offers a new interpretation of Aristotle’s refutation of fatalism. According to this interpretation, each member of a pair of contradictory future contingent statements, in virtue of expressing modal necessity, is simply false. (shrink)

I discuss a short string of five sentences in Metaphysics V.5, 1015b6-9 relating demonstration to necessity. My proposal is that Aristotle focuses his attention on the demonstration as a demonstration. Other interpretations reduce the necessity in question to the modality of the component sentences of the demonstrations (the conclusion and the premises). My view does not deny that the modality of the component sentences is important, but takes seriously the idea that a demonstration itself should be understood as necessary—as not (...) capable of being otherwise. A demonstration cannot be different from what it is in the sense that [i] its components cannot be different from what they are, [ii] its components must be related to each other exactly in the way they are related. Demonstrations aim at the fully appropriate explanation of a given explanandum—and each demonstration is individuated by the explanandum it takes. Thus, the basic idea is that, for the target explanandum that individuates a given demonstration, the premises delivering the fully appropriate explanation cannot be replaces with different ones. I show how this proposal, which explains Aristotle’s language in 1015b6-9 accurately, does not make demonstrations ‘melt down into conditional necessity’, first, because the modality of the component sentences is still importantly involved, second, because the explanatory relation expressed in a demonstration is a necessary fact in the real world, so that the demonstration itself is also necessary (in the way I have explained) inasmuch as it captures that fact. (shrink)

I discuss the exact meaning of the thesis according to which the object of scientific knowledge is necessary. The thesis is expressed by Aristotle in the Posterior Analytics, in his definition of scientific knowledge. The traditional interpretation understands this definition as depending on two parallel and independent requirements, the causality requirement and the necessity requirement. Against this interpretation, I try to show, through the examination of several passages that refer to the definition of scientific knowledge, that the necessity requirement specifies (...) more exactly the causality requirement: what cannot be otherwise is the explanatory relation between the explanandum and the cause by which it is what it is. (shrink)

In Posterior Analytics 71b9 12, we find Aristotle’s definition of scientific knowledge. The definiens is taken to have only two informative parts: scientific knowledge must be knowledge of the cause and its object must be necessary. However, there is also a contrast between the definiendum and a sophistic way of knowing, which is marked by the expression “kata sumbebekos”. Not much attention has been paid to this contrast. In this paper, I discuss Aristotle’s definition paying due attention to this contrast (...) and to the way it interacts with the two conditions presented in the definiens. I claim that the “necessity” condition ammounts to explanatory appropriateness of the cause. (shrink)

I discuss what Aristotle means when he say that scientific demonstration must proceed from necessary principles. I argue that, for Aristotle, scientific demonstration should not be reduced to sound deduction with necessary premises. Scientific demonstration ultimately depends on the fully appropriate explanatory factor for a given explanandum. This explanatory factor is what makes the explanandum what it is. Consequently, this factor is also unique. When Aristotle says that demonstration must proceed from necessary principles, he means that each demonstration requires the (...) principle that is the necessary one for the fully appropriate explanation of its explanandum. This picture also provides a key to understand Aristotle's thesis that scientific explanation depends on essences: it is the essence of the attribute to be explained that should be stated as the fully appropriate explanatory factor. (shrink)

My aim is to figure out whether Aristotle’s response to the argument for fatalism in De Interpretatione 9 is successful. By “response” here I mean not simply the reasons he offers to highlight why fatalism does not accord with how we conduct our lives, but also the solution he devises to block the argument he provides for it. Achieving my aim hence demands that I figure out what exactly is the argument for fatalism he voices, what exactly is his solution, (...) whether his solution is coherent, and whether it does indeed succeed. I find that the argument is essentially bivalence plus that the truth of a proposition stating that an event will happen in the future entails that this event will necessarily happen, that Aristotle’s solution is to restrict bivalence when it comes to propositions about contingent future events, that this solution is coherent, and that while it does not rule out the possibility of fatalism, it does succeed in blocking the argument for fatalism offered within chapter 9. (shrink)

Malink’s interpretation is designed to validate Aristotle’s claims of validity and invalidity of syllogistic-style arguments, as well as his conversion claims. The remaining sorts of claims in Aristotle's text are allowed to fall out as they may. Thus, not all of Aristotle’s examples turn out correct: on some occasions, Aristotle claims that a given pair of terms yields a true (false) sentence of a given type although, under Malink’s interpretation, the sentence in question is false (true). Similarly, some of Aristotle’s (...) claims of invalidity of nonsyllogistic-style arguments come out false. For example, under Malink’s interpretation, ‘A applies to all B’ and ‘B necessarily applies to all C’ entail ‘A necessarily applies to some B’, contrary to what Aristotle says. (shrink)

Aristotle’s Prior Analytics identifies deductions simpliciter with inferential necessity, so that a deduced conclusion is necessarily inferred from some premises. Modern logical reconstructions claim that inferential necessity in Aristotle corresponds to logical validity. However, this logical reconstruction fails on two accounts. First, logical validity does not highlight Aristotle’s distinction between inferential necessity and predicative necessity, meaning that the inferential necessity of a deduction is not of the same kind as the predicative necessity of a non‑deductive argument. Second, logical validity does (...) not explain the relevance of Aristotle’s distinction between complete and incomplete deductions. Logicians speak of complete deduction by adding the term “obvious” or “transparent” to logical validity, and then criticize Aristotle’s view for being unclear. However, Aristotle’s position is not confronted with this difficulty. There is nothing to add to inferential necessity, which already means complete deducibility, as opposed to incomplete deducibility, deemed to be potentially complete. Accordingly, the Prior Analytics reduces the incomplete deductions to the complete deductions in order to prove the potential, inferential necessity of the incomplete deductions. Logical validity would have been faithful to Aristotle’s text, if it had been possible to coin a notion of potential validity, distinct from both validity and invalidity. (shrink)

Many logicians have tried to formalize a modal logic from the Prior Analytics, but the general view is that Aristotle has failed to offer a consistent modal logic there. This paper explains that Aristotle is not interested in modal logic as such. Modalities for him pertain to the relations of predication, without challenging the assertoric system of deductions simpliciter. Thus, demonstrations or dialectical deductions have modal predicates and yet are still deductions simpliciter. It is a matter of distinguishing inferential necessity (...) that applies to every deduction from the modal predicates in the two premises and conclusion. The modality of demonstrations can be either necessary or possible. The necessity is predicative, i.e., independent of inferential necessity. While the possible demonstration challenges the predicative necessity of the necessary demonstration, it preserves the inferential necessity of the deduction simpliciter. (shrink)

On Jaakko Hintikka’s understanding of Aristotle’s modal thought, Aristotle is committed to a version of the Principle of Plenitude, which is the thesis that no genuine possibility will go unactualized in an infinity of time. If in fact Aristotle endorses the Principle of Plenitude, everything becomes necessary. Despite the strong evidence that Aristotle indeed accepts that Principle of Plenitude, there are key texts in which Aristotle seems to contradict it. On Hintikka’s final word on the matter, Aristotle either endorses the (...) Principle of Plenitude or Aristotle is simply inconsistent. Without challenging Hintikka’s interpretation of the relevant texts, I show how Aristotle may accept a form of the Principle of Plenitude that allows for genuine unactualized possibilities in the world. What allows me to reconcile the seemingly inconsistent data is to show how Aristotle is only committed to a de re version of the Principle of Plenitude. After I lay out my proposal, I show how it opens up new ways in which we might understand Aristotle’s attempt to reject fatalism in his De interpretatione 9. (shrink)

At the beginning of the first book of Posterior Analytics, Aristotle‟s feature of demonstrative knowledge involves a certain concept of “necessity”. The traditional interpretation tends to associate this concept with modal necessity, which is found in the Prior Analytics and De interpretatione. The present article aims to show in which way the sixth chapter of book A of Posterior Analytics presupposes a set of essentialist theses that claims to base the necessity of scientific knowledge on predicative relations of essential character. (...) To acknowledge this essentialist background and simultaneously support a modal interpretation of scientific necessity urges us to attribute serious drawbacks to Aristotle‟s theory of demonstration, forcing us to reassess this interpretative tendency. (shrink)

In chapter 9 of De Interpretatione, Aristotle offers a defense of free will against the threat of fatalism. According to the traditional interpretation, Aristotle concedes the validity of the fatalist's arguments and then proceeds to reject the Principle of Bivalence in order to avoid the fatalist's conclusion. Assuming that the traditional interpretation is right on this point, it remains to be seen why Aristotle felt compelled to reject such an intuitive semantic principle rather than challenge the fatalist's inference from truth (...) to necessity. The answer, I contend, lies in Aristotle's theory of truth and truthmakers. (shrink)

Some commentators have argued that there is no room in Aristotle's natural science for simple, or unconditional, physical necessity, for the only necessity that governs all natural substances is hypothetical and teleological. Against this view I argue that, according to Aristotle, there are two types of unconditional physical necessity at work in the material elements, the one teleological, governing their natural motions, and the other non-teleological, governing their physical interaction. I argue as well that these two types of simple necessity (...) also govern everything made out of the elements, that is, all other natural substances and artifacts. (shrink)

That each of these questions has provided occasion for disagreement among able scholars can be readily confirmed by anyone willing to sample even a few items of the now voluminous contemporary literature dealing with this chapter. Indeed, anyone who has puzzled over Aristotle's text and tried to make sense of the relevant secondary literature will be able to sympathize with D. C. Williams' opinion that "tracing coherent philosophical arguments in De Interpretatione is rather like finding shapes in a cloud." Still, (...) I remain convinced that it should be possible to achieve a measure of agreement about the meaning and significance of Aristotle's text beyond any which has yet been attained. Toward this end I shall propose and defend in this paper a set of answers to the disputed questions - which seem to me to do justice both to the text and to the fact that scholarly opinion on these matters has diverged so sharply. (shrink)