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Argument Analysis Exercise
Jason Decker
1 The Assignment
(a) I have given you, in §2, a short passage from Hume. It contains a relatively self- contained argument. Your job is to analyze the argument... (b) First, identify the premises , sub-conclusions , and main conclusion of the argu- ment. i. Main Conclusion: What is ultimately being argued for in the passage. Ask yourself: What claim is the author trying to establish? ii. Sub-conclusions: These are claims that are inferred from previous claims in the argument. iii. Premises: The claims that are being used to establish the sub-conclusions (and, ultimately, the conclusion). iv. NOTE: Sometimes authors leave certain premises (or sub-conclusions—or even conclusions) implicit. The reader is expected to fill them in. You should try to identify any implicit premises, sub-conclusions, or conclusions in the argument. (c) Set out the core argument in numbered premise/conclusion format (see my sample argument analysis below). Explain exactly how the argument is supposed to work. How does the ultimate conclusion follow from the premises? How are the premises themselves established? Are they merely stated, or is some argument given for them? The point is to make clear what the main argument is by distilling it into its core elements and showing how they are logically related to each other. When setting out the argument, try your hardest to reconstruct it in a way that is both faithful to the spirit of the text and also has the best possible shot at being a valid argument (that is, be charitable in your interpretation). (d) Consider whether the various sub-arguments are deductively valid and sound. Recall the following definitions of validity and soundness: i. Validity =df If the premises are true, then the conclusion must also be true. (There’s no possible way to arrange for the premises to be true and the conclusion to be false.) ii. Soundness =df Validity + True Premises. (e) Discuss any important problems that you see in the argument. If you don’t see any important problems, discuss a few potential objections to the argument and indicate how you think they could be answered.
(f) Note: Not everything that’s said in a passage is part of the core argument. You don’t have to find a way to interpret and incorporate every sentence in the passage. Some of the author’s claims will be essential to the core argument; others won’t be. (g) EXTRA CREDIT: [read the Hume passage below first or this won’t make sense] i. Consider the following quote from Charles Babbage’s The Ninth Bridgewater Treatise: [I]f independent witnesses can be found, who speak truth more frequently than falsehood, it is ALWAYS possible to assign a number of independent witnesses, the improbability of the falsehood of whose concurring testimony shall be greater than the improbability of the alleged miracle. ii. Let’s make a few toy assumptions in order to see Babbage’s point more clearly: A. The odds of some miracle, M , happening are one billion to one. B. A group of witnesses, W 1 , ..., Wn, claim to have seen M occur. Suppose that they each came to their judgment completely independently of the other wit- nesses. C. Assume that each witness speaks the truth 60% of the time. (Notice that while they’re more likely than not to speak the truth, they’re not much more likely than not to speak the truth.) iii. Question 1: How many such witnesses to the purported miracle M do we need before the odds that they’ve converged on a false report are worse than the odds that M actually occurred? Explain your reasoning. iv. Question 2: Does your answer to Question 1 put some pressure on Hume’s argu- ment against miracles?
2 The Assigned Passage
[From Hume’s Enquiry (sec X, part i)] A miracle is a violation of the laws of nature; and as a firm and unalterable experience has established these laws, the proof against a miracle, from the very nature of the fact, is as entire as any argument from experience can possibly be imagined. Why is it more than probable, that all men must die; that lead cannot, of itself, remain suspended in the air; that fire consumes wood, and is extinguished by water; unless it be, that these events are found agreeable to the laws of nature, and there is required a violation of these laws, or in other words, a miracle to prevent them? Nothing is esteemed a miracle, if it ever happen in the common course of nature. It is no miracle that a man, seemingly in good health, should die on a sudden: because such a kind of death, though more unusual than any other, has yet been frequently observed to happen. But it is a miracle, that a dead man should come to life; because that has never been observed in any age or country. There must, therefore, be a uniform experience against every miraculous event, otherwise the event would not merit that appellation. And as a uniform experience amounts to a proof, there is here a direct and full proof, from the nature of the fact, against the existence of any miracle; nor can such a proof be destroyed, or the miracle rendered credible, but by an opposite proof, which is superior. The plain consequence is (and it is a general maxim worthy of our attention), ‘that no testimony is sufficient to establish a miracle, unless the testimony be of such a kind, that
3.3 Analysis
The argument is deductively valid. There is no way to arrange for (1) to be true without arranging for (2) to be true, so this sub-argument is valid. Likewise, there is no way to arrange for (2), (3), and (4) to be true without thereby arranging for (5) to be true, so this sub-argument is also valid. Since (6) then follows from (5) immediately, the entire argument is deductively valid. Is the argument sound? Here we might have some serious concerns. Although (1) and (2) seem fairly intuitive, one could worry about sensory episodes that occur during lucid dreams. These seem to be under conscious control, at least to some extent. However, one could easily fix up the argument to get around this worry. All that Locke really needs to get to his conclusion is that some of the ideas we get from sensation are out of our conscious control, and this is surely true. Premise (3) is going to be more problematic. Is it true that if the ideas that I get from a certain faculty are outside of my conscious control, then those ideas must have a cause that’s external to my mind? It’s not obviously so. I see no reason to think that a lack of conscious control over an experience entails that it is caused by something external to the mind. Why couldn’t it rather be caused by a part of the mind the operations of which are inaccessible to introspection and over which the will has no conscious control? Hallucinations, dreams, and feelings of irrational paranoia are a few plausible candidates to have been caused by such a part of the mind. If they are indeed caused by such a part, then (3) is false. Depending on how we are to interpret premise (4), it might also be open to objec- tions. The interpretative issue is this: it’s unclear what Locke has in mind when he talks of “objects without me” (I’ve translated this as ‘external objects’, since the latter inherits the ambiguity of the former and is a bit less arcane). Must an ‘object without me’ be a mind-independent thing, or would another mind that’s external to mine count as an ‘object without me’? From the surrounding context, it’s pretty clear that Locke means to be talking about mind-independent external objects. If this is so, premise (4) could be rejected. After all, the external source of my sensory ideas could be Descartes’ Demon, or—more optimistically—Berkeley’s God-Mind. In sum, although Locke’s argument is valid, there are some reasons to worry about its soundness.
