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Modal fallacy deals with modal logic, a 20th century construct, as user @Virmaior comments in his comment to the question Who Invented the Modal Fallacy?. However, in discussing the sea battle argument for logical fatalism in his De_Interpretatione and his refutation, Aristotle writes (I quote from this internet translation of De_Interpretatione that I found on the internet, happens to be the same as the one used by wikipedia, which cites a broken link):

Let me illustrate. A sea-fight must either take place to-morrow or not, but it is not necessary that it should take place to-morrow, neither is it necessary that it should not take place, yet it is necessary that it either should or should not take place to-morrow. Since propositions correspond with facts, it is evident that when in future events there is a real alternative, and a potentiality in contrary directions, the corresponding affirmation and denial have the same character.

This is the case with regard to that which is not always existent or not always nonexistent. One of the two propositions in such instances must be true and the other false, but we cannot say determinately that this or that is false, but must leave the alternative undecided. One may indeed be more likely to be true than the other, but it cannot be either actually true or actually false. It is therefore plain that it is not necessary that of an affirmation and a denial one should be true and the other false. For in the case of that which exists potentially, but not actually, the rule which applies to that which exists actually does not hold good. The case is rather as we have indicated.

In other words, the only thing that is necessary is the dichotomy (there are only two possible outcomes); neither of the two outcomes are necessary. Therefore, Aristotle essentially states that it is wrong to deduce from "this outcome occurred" that "this outcome necessarily occurs". This is the logical error by which Aristotle refutes the sea battle argument for logical necessity. Yet this is the modal scope fallacy; wikipedia states the fallacy as "a fallacy in the logic of a syllogism whereby a degree of unwarranted necessity is placed," which is the logical error that is going on. Hence, it appears as if Aristotle has recognized the Modal scope fallacy.

However, the Stanford Encyclopedia of Philosophy's article on fatalism, which includes a discussion of Aristotle's sea battle argument and refutaton, while recognizing this view ("On one view he rejects the move from truth to necessity"), asserts that there is ambiguity and presents a second view: "On this view his solution is to deny that it is necessary that the affirmation or the negation is true or false when this relates to things that do not happen of necessity." There are two quotes I identified which support each view coming from Aristotle. The first one, the first part of the second sentence of the second paragraph in the block quote above, "One of the two propositions in such instances must be true and the other false", implies that Aristotle does not reject the law of ambivalence as is claimed by the Stanford Encyclopedia of Philosophy. However, the last part of the very next sentence (third sentence, second paragraph), "it cannot be either actually true or actually false", seems to support the second position. However, this is circumvented if "actually true" and "actually false" refer to logical as opposed to contingent truths.

Hence, though my question is whether my observation that Aristotle recognize the Modal scope fallacy in his rejection of the sea battle argument is correct, it can be narrowed down to whether the first or second view identified in the Stanford Encyclopedia of Philosophy article is correct, and more specifically whether Aristotle does recognize certain concepts of modal logic.

Citations or references to other works of Aristotle, especially in the Organon, are appreciated. According to a comment by @MoziburUllah to this question, in response to my comment which states that modal logic was formulated formally in the 20th century (affirming Virmaior's comment stated above), "Aristotles books on logic - the organon - has a good introduction to the formal consideration of modal logic ie necessity and possibility and their inter-dependence," thus fueling my speculation that Aristotle does recognize the difference between contingent and necessary truths (a view shared by wikipedia), and correctly identifies the Modal scope fallacy.

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Aristotle does in fact recognize the existence of a modal scope fallacy, and I'd argue that he's doing so in the passage you've just quote.

Aristotle is pointing out that the inference from:

"Necessarily (A or not-A)" to "Necessarily A or Necessarily not-A" is not valid. And Aristotle is surely correct about that.

Now I don't know of anywhere that Aristotle starts to think explicitly about the value of that scope distinction. Aristotle sees the force of the point in this particular case, but I'm not sure he ever reflected on the connection between modality and scope explicitly. (I haven't read Aristotle's treatment of modality in the Analytics in a long time, and I might have missed something.)

However, although Aristotle might have recognized the modal scope fallacy as a fallacy, it might still be the case that he himself committed it sometimes. There are a couple of important places in Aristotle's philosophy where it looks like the argument turns upon just that fallacy. For example, early on in the Posterior Analytics (IIRC), Aristotle argues like this:

(1) It must be the case that If I know Socrates is a man, then he is a man. (2) I do know Socrates is a man. (3) Therefore, Socrates must be a man.

In other words, it looks like Aristotle is saying:

(1*) Necessarily (if K, then S) (2*) K (3*) Therefore, necessarily S.

(1*) looks quite plausible, because it simply says that that it is impossible to "know" a falsehood, which seems to capture an important intuitive fact about knowledge. However, (1*)-(3*) contains a modal scope fallacy. There is no valid way to infer (3*) from (1*) and (2*). In order to derive (3*) Aristotle would need a very different first premise (1**):

(1**) If I know Socrates is a man, then necessarily Socrates is a man.

From (1**) and (2*), (3*) would follow validly. However, (1**) is very implausible. I know lots of things, some of the things I know seem like they could have been otherwise. For instance, I know Paris is the capital of France. But it seems absurd to think that the French couldn't have chosen some other city as their capital, such as Nice, or Lyon. The fact that I know something might entail that that thing is true, but that's a far cry from my knowledge entailing that that truth is a necessary truth.

Now, in Aristotle's defense, usually when he's thinking about knowledge, he's thinking about knowledge of the essences of things or knowledge of mathematics, and in these very restrictive cases something like 1** is much more plausible. So it's not necessarily the case that this logical mistake on Aristotle's part is fatal to his overall philosophical project or something. Nevertheless, it does show us something important: even if you are as smart as Aristotle, it pays to be really careful and explicit about your logic to avoid making dumb mistakes.

tl;dr -- Yes Aristotle recognized the modal scope fallacy, even though he also sometimes committed it.

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I do not see any connection between the sea-battle argument and modal logic. The thesis that the sea-battle argument seems to support (which can be put: that future states of affairs exist (already) in the present) is not a modal one, and I don't see how a modal argument could support it. When Aristotle uses the word 'necessary' in this context, he seems to mean 'logically necessary', i.e. true by dint of logic. This is largely equivalent to what was later called 'analytic' and 'tautological'. Here is the quoted paragraph re-rendered using such terms:

Let me illustrate. It is true now that a sea-fight either will take place to-morrow or not, but it does not logically follow that it is either now true that the sea-battle will take place to-morrow, or that it is now true that it will not take place tomorrow, although it is now true that it either will or will not take place to-morrow. Since propositions correspond with facts, it is evident that when in future events there is a real alternative, and a potentiality in contrary directions, the corresponding affirmation and denial have the same character.
This is the case with regard to that which is not always existent or not always nonexistent. It is tautological that one of the two propositions in such instances will be true and the other will be false, but we cannot say determinately that this or that is now false, but must leave the alternative undecided. One may indeed be more likely to be true than the other, but it cannot be either actually true or actually false. It is therefore plain that it is not in general tautological that of an affirmation and a denial, one is true and the other false. For in the case of that which exists potentially, but not actually, the rule which applies to that which exists actually does not hold good. The case is rather as we have indicated.

  • I am talking about the rejection of the sea battle argument, not the argument itself, and am specifically talking about the modal scope fallacy. That being said, necessity being a logical necessity is correct. However, for every explanation of the modal scope fallacy I found online, even those from universities, examples using logical necessity were nearly always presented (I can link them if needed). – Cicero Aug 17 '15 at 3:58
  • @cicero Ok, please link them. – Ram Tobolski Aug 17 '15 at 7:02

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