This article illustrates some applications of formal logic to the development of LD cases. It presupposes familiarity with the elements of formal logic introduced last month. By way of review, an argument is a set of sentences some of which (the premises) are offered in support of another of which (the conclusion). A valid argument is an argument of a form such that if its premises are true, its conclusion must be true, and a sound argument is a valid argument with true premises (and hence a true conclusion). We introduced three valid argument forms which can be combined with each other in a variety of ways: (1) MP-Modus Ponen (p→q, p, so q); (2) MT-Modus Tollens (p→q, ~q, so ~p); and (3) HS-Hypothetical Syllogism (p→q, q→r, so p→r). If any of the foregoing is unfamiliar, you should review the earlier article before proceeding with this one.

I will discuss the applications of logic to LD casing under five headings: burdens, research, contention mapping, value structure, and contention development. My underlying thesis is that an LD case is best conceived as the presentation of one or more deductively valid arguments. Among my more interesting conclusions is that debaters should drastically revise the traditional value premise (or core value) and criterion model of argument.

I. Burdens
There is much confusion about the burdens of LD speakers. What is each side's basic responsibility? What, if anything, must each side prove? This section is the most theoretical in this article. If you don't care about debate theory and simply want to know my answer to the above questions, you can skip to the last paragraph of this section and keep reading from there.

Some LD students and judges are eager to embrace a picture of burdens borrowed from policy debate. In policy debate, there is a standing burden of proof on the affirmative and a corresponding presumption for the negative. That means that in the case of a tie (including the sort of tie that would result if neither side made any speeches), the judge should vote for the negative. The affirmative must prove the policy resolution is true, and the negative must destroy whatever arguments the affirmative makes. However, the negative does not have to prove that the resolution is false.

You might wonder how a policy negative could destroy the affirmative's arguments without proving the resolution false in the process. The answer is, in part, that you can destroy an argument without claiming anything about the truth or falsehood of the argument's conclusion. A good argument is a sound argument. And a sound argument, you will recall, is an argument which is deductively valid and which has only true premises. But an argument which is invalid or which has false premises may still have a true conclusion. Nonetheless, it's a bad argument because we can't know the conclusion is true based on the premises offered. So if we represent the policy resolution as p, the negative team may undermine the affirmative's argument that p without proving (or even attempting to prove) that ~p. There are further reasons why a policy negative can refute the affirmative's argument without actually disproving the resolution, but those reason are related to conventions of policy debate and do not concern us here.

What does concern us is that LD does not have prescribed burdens and presumption comparable to those in policy debate. The NFL's official LD ballot instructs judges that "There are no prescribed burdens in L-D as there are in policy debate; no 'burden of proof' and no 'presumption.'" This means that if there were an argumentative tie in an LD round, the negative would not win by default. No one would win by default.

More importantly, the lack of prescribed burdens means that it is not sufficient in LD, as it is in policy, for the negative merely to attack the affirmative's arguments. The negative must offer constructive arguments of its own, arguments which conclude that the resolution is false. For suppose the affirmative offers two arguments, each of which concludes that p (the resolution) is true. And suppose the negative follows the policy strategy of merely attacking those two arguments-showing that they are insufficient to prove that p. But the negative (as we are supposing) offers no independent arguments to prove that ~p, i.e., that the resolution is false. Then the negative has effectively destroyed the affirmative's reasons for believing the resolution without offering any reasons to disbelieve it. And since there is no presumption in LD, if there are no reasons to believe the resolution and no reasons to disbelieve it, there is no reason for the judge to vote one way or the other.

It's as if the debate begins with a tie (since there is no presumption) and the affirmative case attempts to break the tie by proving the resolution true. If the negative merely disarms the affirmative's attempted tie-breaker, we are back to a tie again. To win, the negative must do more than simply disarm the affirmative's tie-breaker. The negative must attempt to break the tie in the other direction, by proving the resolution false.

So we might think of LD affirmatives as having a burden to prove the resolution true, but only in a sense of "having a burden" such that LD negatives equally have a burden to prove the resolution false. This means that there are no burden strategies which are open to the negative but not to the affirmative just in virtue of the rules of LD. In other words, the standing burdens of each side are symmetrical. Therefore, refuting affirmative arguments is not sufficient to negate an LD resolution.

However, there may still be a range of legitimate negative strategies on this or that particular LD resolution. We can say generally that the negative must prove the resolution false, but there are different ways different kinds of propositions can be falsified.

Consider the resolution that "The possession of nuclear weapons is immoral." It's clear enough what the affirmative is responsible to prove. But what must the negative prove? That the possession of nuclear weapons is morally good? If the negative proved that, the negative would certainly be proving the resolution false. But there are other ways the resolution could be false as well. The negative could prove, less ambitiously, that the possession of nuclear weapons is neither morally good nor bad; it is morally neutral. This conclusion logically implies the falsehood of the resolution. But the resolution is also false (it seems) if morality is a myth-if nothing is morally good, bad, or even neutral. For if no actions have moral properties, it is obviously false that any particular action (such as the possession of nuclear weapons) has the property of being immoral. So even on this simple resolution, there are several routes the negative could take to fulfill its burden of proving the resolution false.

Now consider a more complicated resolution, that "As a general principle, individuals have an obligation to value the common good above their own interests." People often refer to resolutions of this sort as "comparative," and it is comparative resolutions that generate the most controversy about negative burdens. Let us again use p to represent the resolution. What counts as ~p? Many people believe that the negative's burden on such a comparative resolution is to prove the converse of the resolution-in this case, to prove that individuals ought to value their own interests above the common good. And no doubt, if individuals ought to prefer their own interests to the common good, then it's false that individuals ought to prefer the common good to their own interests. So proving the converse is one way for the negative to satisfy its burden to show that ~p.

But there are other ways to show that ~p. Suppose the negative could prove that what an individual should prefer varies from situation to situation and from individual to individual. Then it would be false that as a general principle individuals ought to prefer the common good to their own interests. There is nothing incoherent about this position, and it has been defended by many philosophers. Or suppose the negative could prove that there is a general principle, but that the principle is that individuals ought to value their own interests and the common good equally. I think this principle would be difficult to defend, but if it's true, then the resolution is false, and the negative has yet another way to satisfy its burden.

The position on negative burdens which I am now defending is a reversal of an earlier position. I used to believe that the negative had to defend the converse of a comparative resolution. I still believe that defending the converse often makes for the strongest negative positions, but I no longer believe that the rules of LD or the ethics of argument require the negative to defend the converse.

My present position is likely to please no one. Some people will think it allows too many negative options, including "balance negatives," "situational negatives," or "critical arguments" (I put these terms in quotation marks because I am often unsure what people mean by them). Other people will think my view is too restrictive by requiring the negative to defend a proposition rather than simply attacking the affirmative's arguments.

Of course, I think my view is just right. More specifically, I think it best accounts for two relevant facts: The first fact is that there is no prescribed burden of proof and no presumption in LD. This fact requires that the negative (if it wants to secure a win rather than just a tie) must prove a proposition, namely, the proposition ~p which is the denial of the resolution p. The second fact is that depending on what p says, there may be many ways to prove ~p-including more ways than simply proving the converse of a comparative resolution. I am not equally enthusiastic about all of these ways, but I think anyone who understands the logical significance of denial must at least be open to them.

So in sum we can say that the affirmative's basic burden is to prove that the resolution is true and the negative's basic burden is to prove that the resolution is false. Depending on the resolution, there may be many ways to prove the resolution false. But if we use p to represent the resolution and ~p to represent "it is false that p," then the affirmative case should make arguments the conclusion of which is p, and the negative case should make arguments the conclusion of which is ~p.

II. Research
There are at least two sorts of research relevant to constructing a debate case. The first sort is general research conducted for the purpose of finding arguments to prove a resolution true or false. The second sort is focused research to support this or that premise of an argument which you have already constructed. Here I am concerned only with research of the first sort.

It is best to begin research on every topic by reading several general survey chapters and articles before hunting for specific arguments. These surveys will often be entries in reference books, literature reviews in journals, chapters in textbooks, or introductions in monographs (books by a single author) and edited anthologies. In addition to suggesting further sources to pursue, this reading will acquaint you with the history of the controversy, the main areas of dispute, and the relevant terminology.

Once you move from such background sources into sources which are actually defending a position on your subject, you should begin reading for valid arguments. First identify the conclusion the author of the source is defending. If there are several conclusions, identify the one which is most relevant to the resolution you're debating. Rarely will useful sources on a given topic be defending or denying exactly your resolution. Instead, they may be addressing a closely related area. For example, if you are searching for arguments on the resolution that in the U.S., the use of race as a deciding factor in college admissions is just, you may run across Matt Cavanagh's recent book Against Equality of Opportunity. Cavanagh is writing about the just distribution of jobs in Great Britain, but many of his arguments could be applied to the debate over U.S. college admissions. You should study any argument you think might be relevant to your resolution, even if its conclusion does not match the resolution perfectly.

When you find a relevant argument in prose, you should apply your understanding of formal logic to analyze the argument into numbered premise-conclusion form. This process is difficult to master, but it will greatly enhance your ability to understand (and, eventually, to attack and defend) arguments.

In the course of explaining valid argument forms, we have used italicized letters (p, q, and so forth) to symbolize propositions. When you are formalizing real arguments, do not use letters to stand for propositions. The purpose of formalizing an argument is to grasp its substance-exactly what premises support a particular conclusion-so you should write out the relevant premises and conclusion in normal English.

Most authors will not express their premises in conditional (if-then) sentences, so you will need to paraphrase in order to display the argument's logical structure. And since most authors do not state premises they assume will be obvious to their audiences, you will also have to make these suppressed premises explicit. That's OK as long as you are careful to make your reconstruction of the argument faithful to the author's original ideas. Your goal is simply to understand exactly how the author's argument works.

As suggested above, it is easiest to begin this analysis by identifying the argument's conclusion. It is especially important at this stage to record the author's precise conclusion rather than your debate resolution (or its negation), if the two differ. If the argument's conclusion doesn't quite match your resolution, you can think about how they might be reconciled at a later stage. But at this stage you will distort the author's argument if you try to shoehorn it to fit your immediate debate needs.

Once you have identified the conclusion, work backward to find the other premises. For example, if the conclusion is the simple proposition r, then look next for a premise which you can express as the conditional q→r. Does the author also straightforwardly assert q? If so, you have a complete MP argument. But perhaps the argument is more complex, and the author derives q only from the further premises p→q and p. As we saw in the first article, a valid argument may contain any finite number of iterations of MP, MT, or HS. Fortunately, the formal structure of most real arguments is relatively short; but rarely will an argument for an interesting conclusion be a single instance of MP, MT, or HS, so you should be prepared to encounter a bit of complexity.

Often you will find that the premises an author offers for a conclusion fail to support that conclusion validly. For instance, you may wind up with an argument of this form:

(1) p→q (premise)

(2) q→r (premise)

(3) r→s (premise)

(4) So ~p (conclusion)

Since (1)-(3) are conditionals, all you can derive validly from them is another conditional: pg→s. But the author has apparently jumped from this conditional to the conclusion ~p. When you find what appears to be a logically flawed argument, your first impulse should be to ask whether you have accurately and completely represented the argument. Check your source very carefully to make sure you haven't overlooked or misinterpreted anything the author has said.

If you remain convinced that you have formalized the argument fairly and completely, then ask yourself what, if anything, could be added to the argument to make it valid. In our current example, an additional premise ~s, when combined with the conditional p→s, would license us (by MT) to infer the author's original conclusion ~p. Sometimes authors will deliberately take premises for granted if they believe them to be obviously true. This is more common in popular and journalistic writing than in scholarly writing, but it happens everywhere. For instance, a person might argue that gun control is ineffective from the premise that if gun control were effective, cities such as Chicago and New York which have strict gun control laws would have less gun violence than areas with no gun control laws. The defender of this argument may just take it for granted that cities such as Chicago and New York do not have less gun violence. If you find such an implicit (or "suppressed") premise which is needed to make an argument valid, go ahead and write it into your list of premises, noting in parentheses that it is assumed or implicit rather than expressly stated by the author.

Occasionally you will find a published argument which is by itself invalid and which cannot be patched up by adding an obviously suppressed premise or two. For instance, you may discover that an author is denying the antecedent, inferring ~q from the premises p→q and ~p. This discovery is obviously well worth making. It allows you to eliminate a possible case argument from consideration, and it also alerts you to the fault in an argument your opponents may try to use. You should not, however, suppose that because a particular argument for a conclusion is invalid, the conclusion is false. All you have discovered is that one way of trying to reach the conclusion-the way taken by the invalid argument-does not succeed. There may well be (in fact, certainly are) other, valid ways of reaching the same conclusion.

The more you research, the more arguments you can find and formalize. Formalizing will help you to understand the arguments much better than you would if you just read over them in their original wording. It will often be harder than you initially expect, but you will probably feel a sense of accomplishment and mastery when you have captured an argument and laid bare its structure. You will be in a much better position to compare various argument possibilities and construct the arguments you will defend in your case. With enough practice, you can learn to formalize arguments in your head as you read or hear them, vastly increasing your power as a debater.

III. Contention Mapping
When you have read and analyzed enough arguments to give you a good feel for the main options on each side of the resolution, you are ready to begin mapping case contentions. This process can be very difficult (although it will be much easier if you have carefully analyzed the arguments from your research), but the guiding principle here is simple: Each contention should be a single valid argument which concludes in the resolution or its negation.

If your research has gone well, or if you have a strong imagination, you should have more argument possibilities on each side than you can use in a single case. For most debaters, novice and varsity, it is best to map out all of the possible constructive arguments for each side. (An argument is constructive just in case its conclusion is the resolution or its negation.) You can make the most informed choices between possible arguments when you can compare them in the kind of detail a formal premise-conclusion outline reveals.

Here, too, it is safest and easiest to start with the conclusion and work backward. The conclusion of every constructive argument on a given side will be the same: the resolution (if you are affirmative) or the denial of the resolution (if you are negative). What comes next, "after" the conclusion (if you work backward)? A conditional (if-then) premise which has the conclusion as its consequent. I.e., if your conclusion is the proposition q, the first premise you construct should be of the form pgq for some proposition p. The trick is to figure out what proposition to use for the antecedent of this conditional.

Suppose, for example, that you are mapping affirmative arguments for the resolution that "The United States is morally obligated to mitigate international conflicts." You have come across several authors who argue, in various ways, that the U.S. should mitigate conflicts because the U.S. has promised to do so. How can you map the argument? You know the conclusion will be simply the resolution. And you know that the first premise you map, working backward, will be a conditional statement which says: If p, then [resolution]. What should you fill in for p? Given your initial argument idea, the obvious candidate for p is "the U.S. has promised to mitigate international conflicts." So your complete premise is, "If the U.S. has promised to mitigate international conflicts, then the U.S. is morally obligated to mitigate international conflicts." So far, so good.

What more is needed for a valid argument? You cannot conclude q from p→q alone. You need at least one further premise, p, added to your conditional to give you a valid instance of modus ponens. So you need to add as a premise, "The U.S. has promised to mitigate international conflicts." If you stop at this point, you have mapped a single valid argument:

(1) The U.S. has promised to mitigate international conflicts. (premise)

(2) If the U.S. has promised to mitigate international conflicts, then the U.S. is morally obligated to mitigate international conflicts. (premise)

(3) So the U.S. is morally obligated to mitigate international conflicts. (conclusion)

There is nothing logically wrong with this argument as mapped. However, you may find it useful to supplement the argument by adding more premises which clarify the details of the argument as you plan to defend it. The easiest way to supplement an argument is to ask yourself what you would say to an opponent who asked, about any of your premises, why that premise is true. You can usually answer this question by adding two or more new premises to support your original premise.

What if someone asked why the first premise of the argument above is true? Presumably the research that inspired the argument has given you a detailed idea of how exactly the U.S. promised it would mitigate international conflicts. Perhaps the U.S. signed a treaty (we'll call it "Treaty T") in which it promised to "use all reasonable means, diplomatic and military, to restore peace to war-torn regions of the world." Assuming you have good evidence (in this case, a copy of Treaty T) to support your claim, you could represent your original (1) as the conclusion of further premises, like so:

(1') The U.S. signed Treaty T.(premise)

(1'') If the U.S. signed Treaty T, then the U.S. promised to "use all reasonable means, diplomatic and military, to restore peace to war-torn regions of the world." (premise)

(1''') If the U.S. promised to "use all reasonable means, diplomatic and military, to restore peace to war-torn regions of the world," then the U.S. promised to mitigate international conflicts. (premise)

(1) The U.S. promised to mitigate international conflicts. (premise, from 1', 1, 1')

(2) If the U.S. promised to mitigate international conflicts, then the U.S. is morally obligated to mitigate international conflicts. (premise)

(3) So the U.S. is morally obligated to mitigate international conflicts. (conclusion)

Now you can see how you might supplement a simple premise p or q, such as premise (1): by making it the conclusion of further applications of modus ponens (or modus tollens). When you do this, the original premise remains part of the argument, but you justify it by making explicit the premises supporting it.

What about a conditional premise like (2)? How might you support that premise? Again, think about what you would say if someone asked you why (2) is true. To supplement a conditional premise, you will need to add two new conditional premises to the argument. Here is the recipe:

Write two new conditionals. Make the antecedent of the original conditional the antecedent of the first new conditional. Make the consequent of the original conditional the consequent of the second new conditional. Finally, find a new proposition to serve as both the consequent of the first new conditional and the antecedent of the second new conditional.

So you are supplementing a statement of the form p→q with two statements of the form p→r and r→q. These two new statements yield the original p→q by an application of hypothetical syllogism.

Let's look at how this recipe works in practice. Think about the question, "Why believe that if the U.S. promised to mitigate international conflicts, then the U.S. is morally obligated to mitigate international conflicts?" This question really amounts to something like, "Why is there a moral obligation to keep promises?" To answer the question, you are probably going to have to appeal to a moral theory. Fans of strict promise-keeping tend to like Kant's theory, so we will suppose that's your theory of choice. According to Kant, what is wrong with deliberately breaking a promise is that doing so cannot consistently be willed as a universal law-i.e., breaking promises violates Kant's so-called categorical imperative. Given Kant's reason for thinking that we are morally obligated to keep promises, we can supplement premise (2) by adding:

(2') If the U.S. has promised to mitigate international conflicts, then the U.S. must mitigate international conflicts if it is to act in accord with Kant's categorical imperative.

(2'') If the U.S. must mitigate international conflicts if it is to act in accord with Kant's categorical imperative, then the U.S. is morally obligated to mitigate international conflicts.

The two new premises (2') and (2'') justify (2) in our argument, making more explicit the thought behind that original premise. In an actual contention, as opposed to this argument map, you would want to explain in more detail just what Kant's categorical imperative is, why anyone should care about it, and why it requires promise-keeping.

Expanded in the way we have now suggested, what began as a two-premise argument now has seven premises: (1'), (1), (1'), (1), (2'), (2''), and (2). Both the short and longer versions are equally valid. But the longer version will be more useful when you come to writing the actual contention, because it makes the content of the argument more clear and detailed. We could go on asking the same "Why?" questions of the new premises in our longer argument and supplement the argument even further. We won't do that here, assuming you see roughly how the expansion process works. Keep expanding your map of an argument until the thought behind the argument would be clear to someone who carefully reads through the premises and conclusion.

At this stage, you have found (or created) an idea for a constructive argument and have mapped that idea into valid premise-conclusion form. Your next task is to classify the premises of your mapped argument to get some sense of what kinds of support you would need if you were to adopt the argument as part of your case position. We can think of premises as falling into three broad categories: empirical, normative, and definitional.

Empirical premises are claims which could, in principle, be tested scientifically or with the physical senses. That January is colder than June, that Elvis is alive in Arizona, and that free trade hurts American wages are examples of empirical claims. (The first is true; the second, false; and the third, contested.) Debaters should especially note that all causal claims (claims of the form "X causes Y" or "if X occurs, then Y subsequently occurs") are empirical claims.

Normative (or evaluative) premises make claims about what is good or bad, moral or immoral, valuable or valueless. They are not typically subject to scientific or sensory validation. Examples include that cheating is wrong, that justice requires economic equality, and that citizens ought to vote. Almost all LD resolutions are themselves normative claims.

Definitional (or analytic) claims are true in virtue of the meanings of their words; they are not substantive descriptions of any chunk of physical or moral reality. That all aunts are female, that every whole number is either odd or even, and that a treaty is a promise are all analytic claims. At most, they inform someone of the structure of our concepts and language. You might think that definitional claims are always uncontroversial, but this is not so. Is it true that human genetic engineering is, by definition, the curing of genetic diseases? This is a very controversial claim, and a debater lost the final round of the Glenbrooks tournament several years ago when he built an argument on this premise but could not defend it with an actual definition from a legitimate source.

Many philosophers now believe such distinctions among types of propositions are misleading. However, I believe they are useful for thinking about the premises of debate arguments, and I hope you have a rough feel for what kinds of claims fall under each category. Sometimes it will be hard to tell into which category a given premise falls. But even if a premise straddles two of the categories, it can be helpful to know at least that it definitely does not belong to the third.

As an exercise, let's run through the seven premises of our last argument, classifying them by type. If you were doing this on paper or on a blackboard, you could simply write an "E," "N," or "D" next to each premise when you knew its type.

(1') The U.S. signed Treaty T.

This premise is clearly empirical. It is a simple assertion of historical fact and should be confirmable by checking the relevant documents.

(1'') If the U.S. signed Treaty T, then the U.S. promised to "use all reasonable means, diplomatic and military, to restore peace to war-torn regions of the world."

This premise straddles the fence between empirical and definitional. On the one hand, we would probably need to find documentary evidence of just what Treaty T said in order to assess the truth of the premise. On the other hand, the premise could be taken as simply defining (in part) the content of Treaty T-signing Treaty T includes that promise because that's just what Treaty T is.

(1''') If the U.S. promised to "use all reasonable means, diplomatic and military, to restore peace to war-torn regions of the world," then the U.S. promised to mitigate international conflicts.

This premise is clearly definitional. It simply translates the language of the treaty into the language of the resolution.

(1) The U.S. promised to mitigate international conflicts.

This premise does not fall under any of our three headings, because it is not, strictly speaking, a premise. It is a subconclusion of premises (1'), (1), and (1'). It does not aim to supply new information but simply helps the audience grasp the logical/conceptual relationships among other premises. But if (1) were not a subconclusion and instead functioned as a free-standing premise, it would clearly be empirical, because it is a claim about a verifiable action the U.S. has taken in history.

(2') If the U.S. has promised to mitigate international conflicts, then the U.S. must mitigate international conflicts if it is to act in accord with Kant's categorical imperative.

Classifying this premise is tricky because of the intricacies of Kant's philosophy. If Kant had asserted (2'), he probably would have meant it as a definitional truth: Once a person understands the concept of a promise, he will be able to see that it would be logically impossible to will as a universal law that promises be broken.

(2'') If the U.S. must mitigate international conflicts if it is to act in accord with Kant's categorical imperative, then the U.S. is morally obligated to mitigate international conflicts.

This premise is clearly normative. It makes a substantive claim about the content of moral obligations, namely, that a nation is morally obligated to act in accord with the categorical imperative.

(2) If the U.S. promised to mitigate international conflicts, then the U.S. is morally obligated to mitigate international conflicts.

Like (1), (2) is no longer really a premise, because it is now a subconclusion from (2') and (2''). But if (2) were a free-standing premise, it would clearly be normative.

(3) So the U.S. is morally obligated to mitigate international conflicts. (conclusion)

The conclusion is, obviously, a normative claim. It's the resolution, and LD resolutions (as we've said) are normative claims.

You should classify the premises of all the possible case arguments you map. When you think about which one or two (never more than three) arguments to build into your case, you should compare the varying empirical, normative, and definitional burdens you'd be assuming by adopting each argument. It will not be enough in the case merely to state your premises and explain how the conclusion logically follows. You will also have to persuade your audience that each premise is true, and some premises are easier to sell than others.

Any empirical premise is going to need empirical evidence to support it. That means if you don't have good evidence to back a premise at the time you first map an argument, you will have to find good evidence if you decide to include that argument in your case. LD students are especially prone to think that causal claims can be supported "logically" rather than empirically. This is false. Logic does not have the resources to prove causal statements about events in the world. (If you do not believe this, read Section IV of David Hume's first Enquiry.) When someone says that "it's just obvious" that one type of action or event will cause another type of action or event, all that person really means is that it seems obvious to him. There is no way to know what actions will cause what effects without empirical investigation. Particularly when large-scale social phenomena are at play (as they often are in LD resolutions), armchair predictions about causes and effects have a very bad track record. You must have expert evidence that the world really works the way you claim it does if you expect your empirical premises to be credible to your audience.

Good empirical evidence is hard to find, and the more empirical premises an argument has, the more evidence you will need. Because consequentialist arguments depend on the actual empirical results of an action to determine its morality, such arguments will typically require more empirical evidence than deontological or other non-consequentialist arguments require. Many debaters think that consequentialist arguments are somehow more objective and therefore easier to defend than are deontological arguments. But there is nothing in the structure of consequentialist arguments that should lead you to believe that. Any valid argument for a normative conclusion is going to contain at least one normative premise, and this is just as true of valid consequentialist arguments as of others. The only difference between consequentialist and non-consequentialist arguments on this score is that the former add controversial empirical premises to their controversial normative premises. Debaters who wish to minimize their reliance on empirical evidence may want to avoid consequentialist arguments, especially consequentialist arguments with multiple causal premises.

Notice that our sample argument above has an empirical premise (1') even though it is not a consequenialist argument. However, you should be able to see immediately that not all empirical premises are created equal. Premise (1') requires evidence, but the evidence will be an uncontroversial report of a public event, the signing of a treaty. This kind of empirical evidence is much easier to find and to defend than is evidence on (say) the climatic effects of carbon dioxide or the deterrent effects of capital punishment.

Normative premises will not require empirical evidence, but they will typically require persuasive explanation and perhaps a vivid illustration. Supporting a normative premise is likely to require more hard thought than any other element of an argument. So understand, when you compare argument options, that you will have to defend your normative premises in the case.

Definitional premises vary greatly in the kind and amount of support they require. Sometimes appeal to a standard dictionary (or even to the linguistic intuitions of your audience) is enough support for simple definitional claims. At other times, especially when a claim concerns technical or otherwise unfamiliar concepts, you will need expert evidence.

Finally, if a "premise" is really just a subconclusion of previous premises, you might want to explain how it follows so that your audience can fully grasp the logical connections you are claiming.

Since this is not an article on casing per se, I will not go into detail on how the various types of premises should be supported (although I offer a few tips in Part V below). But it is important, before selecting your case arguments, to understand what kinds of premises each argument includes and to have a rough sense about what kinds of support each type of premise will require.

If you end up choosing more than one argument for your case, check to be sure the premises of all your arguments are compatible. You do not want to defend a premise in one argument which you deny a few paragraphs later in a different argument. Be especially certain that the normative premises of all your arguments more or less tally with each other. It is not necessary to have the same normative premises in each argument (although this is often possible, and a good idea). But make sure you are not endorsing incompatible moral theories at different points in your case, and that you can explain, if asked, how a person could hold all your normative premises as part of a coherent moral outlook.

[Editor's Note: Due to the length of this article, it's fourth and fifth sections, on value standards and contention development, will appear in next month's Rostrum.]

(Jason Baldwin (jbaldwin@nd.edu) is a Ph.D. candidate in philosophy at the University of Notre Dame. A nationally successful debater and coach, he has directed the LD curriculum of the Kentucky National Debate Institute since 1997. Many of his past Rostrum contributions can be found on NFL's online archive.)