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The Art of Economic Argument - Going Beyond Aristotelian Logic 1.

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1 The Art of Economic Argument - Going Beyond Aristotelian Logic 1

2 Aristotelian Logic Aristotle’s syllogisms emphasize the central concept of validity. Visualizing syllogisms in terms of the three-circle Venn diagrams gives us a picture of validity in the strongest Aristotelian sense: airtight, ironclad validity. In this talk, we will go beyond Aristotle to look at validity much more broadly. In general, validity refers to the degree of support between premises and conclusion. Does this fact support this claim? Do these premises render the conclusion highly plausible? Does this evidence give us good reason to believe the conclusion? The reasoning may not be airtight, but is it solid enough to act upon? 2

3 Aristotle’s Square of Opposition 3

4 Beyond the Syllogism 1. Spending $50 billion in annual economic aid to foreign countries would be justified only if we knew that either they would genuinely benefit from the exchange or we would. 2. We don’t know that we would benefit from the exchange. 3. It might further weaken our already vulnerable economy. 4. We don’t know that they would genuinely benefit. 4

5 Beyond the Syllogism 5. The track record of foreign aid that has been misdirected, misappropriated, or lost in foreign corruption is all too familiar. 6. With $50 billion a year, we could offer college scholarships to every high school graduate and major health benefits for every man, woman, and child in the United States Our obligations are first and foremost to our fellow citizens. 8. We should spend the $50 billion here rather than in foreign aid. 5

6 How Good is the Argument? There are lots of premises in that argument, far more than in Aristotle’s syllogisms, and lots of transition steps. Together, they are intended to drive us toward the conclusion. But how good is the argument? And how should we analyze an argument such as this? Trying to deconstruct it into syllogisms is nearly impossible. We will see how to analyze it later. 6

7 Flow Diagram The best way to analyze complex arguments is with a simple visualization: a flow diagram. Such a diagram will help us see the validity of a complex argument. Breaks, disconnects, and weak logical links can show us invalidity in an argument. 7

8 The Basic Rule The basic rule is simple: When one claim is intended to support another, we put an arrow from the first to the second. The problem, however, is that propositions don’t come labeled as premises or conclusions. They can function in either role. It all depends on the context, on the structure of the argument. Another difficulty is that the first sentence you hear doesn’t always come first logically. 8

9 Example Consider this argument, for example: (1) If the governor is impeached, we might be no better off. (2) Impeaching the governor would require another election. (3) But there is always the chance that people would then vote for someone equally corrupt. 9

10 Ordering the Propositions The propositions are numbered in the order of presentation, but what we want to know is something different. We want to know where the reasoning flows from and where it flows to. It will help if we can identify the conclusion. Which is the conclusion: (1), (2), or (3)? 10

11 Reordering It’s proposition (1) that is the conclusion, right at the beginning. Everything else is offered in support of that conclusion. The logic of the argument starts from (2), which leads to (3). And that leads to the conclusion: If the governor is impeached, we might be no better off. 11

12 Branching Flow Diagrams Of course, arguments get more complicated than that, so we need to add complications in the flow diagrams. First of all, arrows can branch. A set of propositions can lead to multiple conclusions or parallel conclusions. 12

13 Example Think about how to graph the following: (1) We can get only so much money from taxes; taxation resources have to be balanced among different social needs. (2) Taxation for prisons must, therefore, be balanced against taxation for education. (3) If we build more prisons, we’ll have less for education. (4) If we spend more on education, we’ll have less for the prisons we may need. 13

14 Branching Conclusions That argument has branching conclusions. The first proposition leads directly to the second. From (1) we graph an arrow to (2), but at that point, our arrows branch. 14

15 Branching In Further, just as arrows can branch out, they can branch in. Sometimes several propositions lead to the same place. 15

16 Example Consider this example: (1) We are dangerously reliant on foreign energy sources. (2) Our oil comes primarily from the Middle East. (3) Most of our natural gas does, as well. (4) Even the elements in our batteries come from such places as Zambia, Nairobi, and China. 16

17 Convergence First, find the conclusion. The conclusion is the first sentence. Each of the other propositions is an argument for that conclusion in its own right. We graph it by having arrows converge on a single conclusion. 17

18 Independent and Dependent Reasons Independent reasons function independently. But sometimes reasons have to function together in order to lead to a conclusion. Dependent reasons only function together. In a case where all three propositions work together as dependent reasons, we can mark them like this: 18

19 Stress Testing How do we know whether propositions are working independently or dependently toward a conclusion? The answer is argument stress testing. If we have independent reasons and one of them fails, the argument should still go through. If we knock out a reason and the argument is still standing, it must be an independent reason. However, that won’t hold for dependent reasons. 19

20 Graphing Complex Arguments We now have the basic elements of any argument flow diagram. But when we start to graph real arguments, we can see how those elements can combine into an immense variety of structures. 20

21 Revisiting Previous Argument Consider the argument we started with above, about spending $50 billion in foreign aid or for college scholarships here. The conclusion is (8). How are the rest of the propositions meant to support that conclusion? Here’s a sketch of that argument: 21

22 Argument Clusters The argument uses two dependent clusters, functioning independently of each other. One cluster uses (1), (2), and (4): Together, they offer an independent argument. If a stress test showed that the information about the college education in (6) and (7) was false, then (1), (2), and (3) together would still stand as an independent argument for the conclusion. Propositions (3) and (5) are backups for (2) and (4). All those together make one argument for the conclusion. Another argument comes from (6) and (7) working together. 22

23 Data and Warrants We can expand on flow diagrams for arguments using the work of the philosopher Stephen Toulmin. We have talked about premises that function together, representing them as numbers 23

24 Data and Warrants What Toulmin points out is that there is often more structure just beneath that plus sign. Some of those numbers may stand for premises that function as what he calls data. Some function instead as what he calls warrants. They function together but in a very specific way. 24

25 From Data to Warrant to Conclusion Any argument starts with some kind of data. But an argument often doesn’t just go from data to conclusion. It has a middle step—a step that says how the data are supposed to lead to the conclusion. Thus, instead of a plus sign between premises (1) and (2), it might be better to represent them like this:

26 Example The total revenue test can help policymakers determine which tax is best in terms of being able to raise as much revenue as possible with the least deadweight loss. If a good is price inelastic it might be a good candidate for a tax. Therefore, it might be a good idea for policymakers to try to use the total revenue test when choosing which goods to tax. 26

27 A Global Carbon Tax or Cap-and Trade? 27


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