Saturday, January 31, 2009


What are fallacies?

Fallacies are defects that weaken arguments. By learning to look for them in your own and others' writing, you can strengthen your ability to evaluate the arguments you make, read, and hear. It is important to realize two things about fallacies: First, fallacious arguments are very, very common and can be quite persuasive, at least to the causal reader or listener. You can find dozens of examples of fallacious reasoning in newspapers, advertisements, and other sources. Second, it is sometimes hard to evaluate whether an argument is fallacious. An argument might be very weak, somewhat weak, somewhat strong, or very strong. An argument that has several stages or parts might have some strong sections and some weak ones. The goal of this handout, then, is not to teach you how to label arguments as fallacious or fallacy-free, but to help you look critically at your own arguments and move them away from the "weak" and toward the "strong" end of the continuum.

So what do fallacies look like?

For each fallacy listed, there is a definition or explanation, an example, and a tip on how to avoid committing the fallacy in your own arguments.

1) Hasty generalization

Definition: Making assumptions about a whole group or range of cases based on a sample that is inadequate (usually because it is atypical or just too small). Stereotypes about people ("frat boys are drunkards," "grad students are nerdy," etc.) are a common example of the principle underlying hasty generalization.

Example: "My roommate said her philosophy class was hard, and the one I'm in is hard, too. All philosophy classes must be hard!" Two people's experiences are, in this case, not enough on which to base a conclusion.

Tip: Ask yourself what kind of "sample" you're using: Are you relying on the opinions or experiences of just a few people, or your own experience in just a few situations? If so, consider whether you need more evidence, or perhaps a less sweeping conclusion. (Notice that in the example, the more modest conclusion "Some philosophy classes are hard for some students" would not be a hasty generalization.)

2) Missing the point

Definition: The premises of an argument do support a particular conclusion—but not the conclusion that the arguer actually draws.

Example: "The seriousness of a punishment should match the seriousness of the crime. Right now, the punishment for drunk driving may simply be a fine. But drunk driving is a very serious crime that can kill innocent people. So the death penalty should be the punishment for drunk driving." The argument actually supports several conclusions—"The punishment for drunk driving should be very serious," in particular—but it doesn't support the claim that the death penalty, specifically, is warranted.

Tip: Separate your premises from your conclusion. Looking at the premises, ask yourself what conclusion an objective person would reach after reading them. Looking at your conclusion, ask yourself what kind of evidence would be required to support such a conclusion, and then see if you've actually given that evidence. Missing the point often occurs when a sweeping or extreme conclusion is being drawn, so be especially careful if you know you're claiming something big.

3) Post hoc (also called false cause)

This fallacy gets its name from the Latin phrase "post hoc, ergo propter hoc," which translates as "after this, therefore because of this."

Definition: Assuming that because B comes after A, A caused B. Of course, sometimes one event really does cause another one that comes later—for example, if I register for a class, and my name later appears on the roll, it's true that the first event caused the one that came later. But sometimes two events that seem related in time aren't really related as cause and event. That is, correlation isn't the same thing as causation.

Examples: "President Jones raised taxes, and then the rate of violent crime went up. Jones is responsible for the rise in crime." The increase in taxes might or might not be one factor in the rising crime rates, but the argument hasn't shown us that one caused the other.

Tip: To avoid the post hoc fallacy, the arguer would need to give us some explanation of the process by which the tax increase is supposed to have produced higher crime rates. And that's what you should do to avoid committing this fallacy: If you say that A causes B, you should have something more to say about how A caused B than just that A came first and B came later!

4) Slippery slope

Definition: The arguer claims that a sort of chain reaction, usually ending in some dire consequence, will take place, but there's really not enough evidence for that assumption. The arguer asserts that if we take even one step onto the "slippery slope," we will end up sliding all the way to the bottom; he or she assumes we can't stop halfway down the hill.

Example: "Animal experimentation reduces our respect for life. If we don't respect life, we are likely to be more and more tolerant of violent acts like war and murder. Soon our society will become a battlefield in which everyone constantly fears for their lives. It will be the end of civilization. To prevent this terrible consequence, we should make animal experimentation illegal right now." Since animal experimentation has been legal for some time and civilization has not yet ended, it seems particularly clear that this chain of events won't necessarily take place. Even if we believe that experimenting on animals reduces respect for life, and loss of respect for life makes us more tolerant of violence, that may be the spot on the hillside at which things stop—we may not slide all the way down to the end of civilization. And so we have not yet been given sufficient reason to accept the arguer's conclusion that we must make animal experimentation illegal right now.

Like post hoc, slippery slope can be a tricky fallacy to identify, since sometimes a chain of events really can be predicted to follow from a certain action. Here's an example that doesn't seem fallacious: "If I fail English 101, I won't be able to graduate. If I don't graduate, I probably won't be able to get a good job, and I may very well end up doing temp work or flipping burgers for the next year."

Tip: Check your argument for chains of consequences, where you say "if A, then B, and if B, then C," and so forth. Make sure these chains are reasonable.

5) Weak analogy

Definition: Many arguments rely on an analogy between two or more objects, ideas, or situations. If the two things that are being compared aren't really alike in the relevant respects, the analogy is a weak one, and the argument that relies on it commits the fallacy of weak analogy.

Example: "Guns are like hammers—they're both tools with metal parts that could be used to kill someone. And yet it would be ridiculous to restrict the purchase of hammers—so restrictions on purchasing guns are equally ridiculous." While guns and hammers do share certain features, these features (having metal parts, being tools, and being potentially useful for violence) are not the ones at stake in deciding whether to restrict guns. Rather, we restrict guns because they can easily be used to kill large numbers of people at a distance. This is a feature hammers do not share—it'd be hard to kill a crowd with a hammer. Thus, the analogy is weak, and so is the argument based on it.

If you think about it, you can make an analogy of some kind between almost any two things in the world: "My paper is like a mud puddle because they both get bigger when it rains (I work more when I'm stuck inside) and they're both kind of murky." So the mere fact that you draw an analogy between two things doesn't prove much, by itself.

Arguments by analogy are often used in discussing abortion—arguers frequently compare fetuses with adult human beings, and then argue that treatment that would violate the rights of an adult human being also violates the rights of fetuses. Whether these arguments are good or not depends on the strength of the analogy: do adult humans and fetuses share the property that gives adult humans rights? If the property that matters is having a human genetic code or the potential for a life full of human experiences, adult humans and fetuses do share that property, so the argument and the analogy are strong; if the property is being self-aware, rational, or able to survive on one's own, adult humans and fetuses don't share it, and the analogy is weak.

Tip: Identify what properties are important to the claim you're making, and see whether the two things you're comparing both share those properties.

6) Appeal to authority

Definition: Often we add strength to our arguments by referring to respected sources or authorities and explaining their positions on the issues we're discussing. If, however, we try to get readers to agree with us simply by impressing them with a famous name or by appealing to a supposed authority who really isn't much of an expert, we commit the fallacy of appeal to authority.

Example: "We should abolish the death penalty. Many respected people, such as actor Guy Handsome, have publicly stated their opposition to it." While Guy Handsome may be an authority on matters having to do with acting, there's no particular reason why anyone should be moved by his political opinions—he is probably no more of an authority on the death penalty than the person writing the paper.

Tip: There are two easy ways to avoid committing appeal to authority: First, make sure that the authorities you cite are experts on the subject you're discussing. Second, rather than just saying "Dr. Authority believes x, so we should believe it, too," try to explain the reasoning or evidence that the authority used to arrive at his or her opinion. That way, your readers have more to go on than a person's reputation. It also helps to choose authorities who are perceived as fairly neutral or reasonable, rather than people who will be perceived as biased.

7) Ad populum

Definition: The Latin name of this fallacy means "to the people." There are several versions of the ad populum fallacy, but what they all have in common is that in them, the arguer takes advantage of the desire most people have to be liked and to fit in with others and uses that desire to try to get the audience to accept his or her argument. One of the most common versions is the bandwagon fallacy, in which the arguer tries to convince the audience to do or believe something because everyone else (supposedly) does.

Example: "Gay marriages are just immoral. 70% of Americans think so!" While the opinion of most Americans might be relevant in determining what laws we should have, it certainly doesn't determine what is moral or immoral: There was a time where a substantial number of Americans were in favor of segregation, but their opinion was not evidence that segregation was moral. The arguer is trying to get us to agree with the conclusion by appealing to our desire to fit in with other Americans.

Tip: Make sure that you aren't recommending that your audience believe your conclusion because everyone else believes it, all the cool people believe it, people will like you better if you believe it, and so forth. Keep in mind that the popular opinion is not always the right one!

8) Ad hominem and tu quoque

Definitions: Like the appeal to authority and ad populum fallacies, the ad hominem ("against the person") and tu quoque ("you, too!") fallacies focus our attention on people rather than on arguments or evidence. In both of these arguments, the conclusion is usually "You shouldn't believe So-and-So's argument." The reason for not believing So-and-So is that So-and-So is either a bad person (ad hominem) or a hypocrite (tu quoque). In an ad hominem argument, the arguer attacks his or her opponent instead of the opponent's argument.

Examples: "Andrea Dworkin has written several books arguing that pornography harms women. But Dworkin is an ugly, bitter person, so you shouldn't listen to her." Dworkin's appearance and character, which the arguer has characterized so ungenerously, have nothing to do with the strength of her argument, so using them as evidence is fallacious.

In a tu quoque argument, the arguer points out that the opponent has actually done the thing he or she is arguing against, and so the opponent's argument shouldn't be listened to. Here's an example: Imagine that your parents have explained to you why you shouldn't smoke, and they've given a lot of good reasons—the damage to your health, the cost, and so forth. You reply, "I won't accept your argument, because you used to smoke when you were my age. You did it, too!" The fact that your parents have done the thing they are condemning has no bearing on the premises they put forward in their argument (smoking harms your health and is very expensive), so your response is fallacious.

Tip: Be sure to stay focused on your opponents' reasoning, rather than on their personal character. (The exception to this is, of course, if you are making an argument about someone's character—if your conclusion is "President Clinton is an untrustworthy person," premises about his untrustworthy acts are relevant, not fallacious.)

9) Appeal to pity

Definition: The appeal to pity takes place when an arguer tries to get people to accept a conclusion by making them feel sorry for someone.

Examples: "I know the exam is graded based on performance, but you should give me an A. My cat has been sick, my car broke down, and I've had a cold, so it was really hard for me to study!" The conclusion here is "You should give me an A." But the criteria for getting an A have to do with learning and applying the material from the course; the principle the arguer wants us to accept (people who have a hard week deserve A's) is clearly unacceptable. The information the arguer has given might feel relevant and might even get the audience to consider the conclusion—but the information isn't logically relevant, and so the argument is fallacious. Here's another example: "It's wrong to tax corporations—think of all the money they give to charity, and of the costs they already pay to run their businesses!"

Tip: Make sure that you aren't simply trying to get your audience to agree with you by making them feel sorry for someone.

10) Appeal to ignorance

Definition: In the appeal to ignorance, the arguer basically says, "Look, there's no conclusive evidence on the issue at hand. Therefore, you should accept my conclusion on this issue."

Example: "People have been trying for centuries to prove that God exists. But no one has yet been able to prove it. Therefore, God does not exist." Here's an opposing argument that commits the same fallacy: "People have been trying for years to prove that God does not exist. But no one has yet been able to prove it. Therefore, God exists." In each case, the arguer tries to use the lack of evidence as support for a positive claim about the truth of a conclusion. There is one situation in which doing this is not fallacious: If qualified researchers have used well-thought-out methods to search for something for a long time, they haven't found it, and it's the kind of thing people ought to be able to find, then the fact that they haven't found it constitutes some evidence that it doesn't exist.

Tip: Look closely at arguments where you point out a lack of evidence and then draw a conclusion from that lack of evidence.

11) Straw man

Definition: One way of making our own arguments stronger is to anticipate and respond in advance to the arguments that an opponent might make. In the straw man fallacy, the arguer sets up a wimpy version of the opponent's position and tries to score points by knocking it down. But just as being able to knock down a straw man, or a scarecrow, isn't very impressive, defeating a watered-down version of your opponents' argument isn't very impressive either.

Example: "Feminists want to ban all pornography and punish everyone who reads it! But such harsh measures are surely inappropriate, so the feminists are wrong: porn and its readers should be left in peace." The feminist argument is made weak by being overstated—in fact, most feminists do not propose an outright "ban" on porn or any punishment for those who merely read it; often, they propose some restrictions on things like child porn, or propose to allow people who are hurt by porn to sue publishers and producers, not readers, for damages. So the arguer hasn't really scored any points; he or she has just committed a fallacy.

Tip: Be charitable to your opponents. State their arguments as strongly, accurately, and sympathetically as possible. If you can knock down even the best version of an opponent's argument, then you've really accomplished something.

12) Red herring

Definition: Partway through an argument, the arguer goes off on a tangent, raising a side issue that distracts the audience from what's really at stake. Often, the arguer never returns to the original issue.

Example: "Grading this exam on a curve would be the most fair thing to do. After all, classes go more smoothly when the students and the professor are getting along well." Let's try our premise-conclusion outlining to see what's wrong with this argument:

Premise: Classes go more smoothly when the students and the professor are getting along well.

Conclusion: Grading this exam on a curve would be the most fair thing to do.

When we lay it out this way, it's pretty obvious that the arguer went off on a tangent—the fact that something helps people get along doesn't necessarily make it more fair; fairness and justice sometimes require us to do things that cause conflict. But the audience may feel like the issue of teachers and students agreeing is important and be distracted from the fact that the arguer has not given any evidence as to why a curve would be fair.

Tip: Try laying your premises and conclusion out in an outline-like form. How many issues do you see being raised in your argument? Can you explain how each premise supports the conclusion?

13) False dichotomy

Definition: In false dichotomy, the arguer sets up the situation so it looks like there are only two choices. The arguer then eliminates one of the choices, so it seems that we are left with only one option: the one the arguer wanted us to pick in the first place. But often there are really many different options, not just two—and if we thought about them all, we might not be so quick to pick the one the arguer recommends!

Example: "Caldwell Hall is in bad shape. Either we tear it down and put up a new building, or we continue to risk students' safety. Obviously we shouldn't risk anyone's safety, so we must tear the building down." The argument neglects to mention the possibility that we might repair the building or find some way to protect students from the risks in question—for example, if only a few rooms are in bad shape, perhaps we shouldn't hold classes in those rooms.

Tip: Examine your own arguments: If you're saying that we have to choose between just two options, is that really so? Or are there other alternatives you haven't mentioned? If there are other alternatives, don't just ignore them—explain why they, too, should be ruled out. Although there's no formal name for it, assuming that there are only three options, four options, etc. when really there are more is similar to false dichotomy and should also be avoided.

14) Begging the question

Definition: A complicated fallacy; it comes in several forms and can be harder to detect than many of the other fallacies we've discussed. Basically, an argument that begs the question asks the reader to simply accept the conclusion without providing real evidence; the argument either relies on a premise that says the same thing as the conclusion (which you might hear referred to as "being circular" or "circular reasoning"), or simply ignores an important (but questionable) assumption that the argument rests on. Sometimes people use the phrase "beg the question" as a sort of general criticism of arguments, to mean that an arguer hasn't given very good reasons for a conclusion, but that's not the meaning we're going to discuss here.

Examples: "Active euthanasia is morally acceptable. It is a decent, ethical thing to help another human being escape suffering through death." Let's lay this out in premise-conclusion form:

Premise: It is a decent, ethical thing to help another human being escape suffering through death.

Conclusion: Active euthanasia is morally acceptable.

If we "translate" the premise, we'll see that the arguer has really just said the same thing twice: "decent, ethical" means pretty much the same thing as "morally acceptable," and "help another human being escape suffering through death" means "active euthanasia." So the premise basically says, "active euthanasia is morally acceptable," just like the conclusion does! The arguer hasn't yet given us any real reasons why euthanasia is acceptable; instead, she has left us asking "well, really, why do you think active euthanasia is acceptable?" Her argument "begs" (that is, evades) the real question.

Here's a second example of begging the question, in which a dubious premise which is needed to make the argument valid is completely ignored: "Murder is morally wrong. So active euthanasia is morally wrong." The premise that gets left out is "active euthanasia is murder." And that is a debatable premise—again, the argument "begs" or evades the question of whether active euthanasia is murder by simply not stating the premise. The arguer is hoping we'll just focus on the uncontroversial premise, "Murder is morally wrong," and not notice what is being assumed.

Tip: One way to try to avoid begging the question is to write out your premises and conclusion in a short, outline-like form. See if you notice any gaps, any steps that are required to move from one premise to the next or from the premises to the conclusion. Write down the statements that would fill those gaps. If the statements are controversial and you've just glossed over them, you might be begging the question. Next, check to see whether any of your premises basically says the same thing as the conclusion (but in other words). If so, you're begging the question. The moral of the story: You can't just assume or use as uncontroversial evidence the very thing you're trying to prove.

15) Equivocation

Definition: Equivocation is sliding between two or more different meanings of a single word or phrase that is important to the argument.

Example: "Giving money to charity is the right thing to do. So charities have a right to our money." The equivocation here is on the word "right": "right" can mean both something that is correct or good (as in "I got the right answers on the test") and something to which someone has a claim (as in "everyone has a right to life"). Sometimes an arguer will deliberately, sneakily equivocate, often on words like "freedom," "justice," "rights," and so forth; other times, the equivocation is a mistake or misunderstanding. Either way, it's important that you use the main terms of your argument consistently.

Tip: Identify the most important words and phrases in your argument and ask yourself whether they could have more than one meaning. If they could, be sure you aren't slipping and sliding between those meanings.

Friday, December 26, 2008

Do you agree that Philippines should amend or revise the 1987 Constitution?

Confucius, China’s most famous teacher, philosopher and political theorist in 551-479 BC quotes that “It is only the wisest and the stupidest that cannot change.” Hence, “the only thing that is constant is change”.

The change of the Constitution may not be the wisest option to spur progress, a treadmill to the nation seeking to liberate itself from the shackles of obsolete rules no longer conformable to the country’s needs and aspiration, yet resistance from it would be the stupidest thing one can do to his country.

However, some Filipinos viewed instinctively that changing of the Philippine Constitution is a threat or a predicament rather than a challenge to be embraced. Undeniably, laymen and antagonists presumed, that its necessity is dictated merely from the whims, caprices, passing fancies, temporary passions or occasional infatuations of the people with ideas or personalities and purposely to suit political expediency, personal ambitions or ill-advised agitation thus, heedlessly precluding without thorough evaluation of its beneficiality and practicability and whether or not if favors only to selected members of the society and deliberately its effects to the nation as a whole.

Noticeably, the 1987 Constitution had been in effect for 20 years and no amendments or changes had been introduced to improve it. Therefore, it is just about time to amend or revise the charter. Though, it’s true that the people’s traumatic experience of Martial Law and the fear of Marcos’ ghost casting doubts on the proposal to change the constitution, yet this can be eradicated if and only if the Filipino people will be educated on the pros and cons of every proposed amendment or provision. To ensure further the authenticity of the intention of the change, there should be fair, honest and objective information dissemination. On the other hand, amendments and revision of the charter should be done in a most appropriate manner which is in accordance with Art. XV11 of the 1987 Constitution.

Scrutinizing the strengths and the weaknesses of each proposal shall be useful in defeating the evils of the said proposal while promoting the good side of it. Let’s take into account, the most controversial shift from bicameral – presidential form of government to unicameral – parliamentary form of government. One of its advantages is the decentralization of power of which the local government units shall be given the powers to ensure efficient delivery of basic services. However, some feared that if this will have happen, there will be a possibility of the rebirth of private armies since those politicians has the tendency to stay in power by all means. (This was experienced before in some regions.)

By properly laying down its advantages we can more likely aimed to impede its disadvantages through implementing prohibiting laws or statutes or strengthening existing statutes to prevent the occurrence of such weaknesses. Since, we are being pre-empted on the possible outcome, then we can probably formulate solutions to it. Oftentimes, we stare our problem for too long lest we forget to think of the solutions

Thursday, December 18, 2008

Do the 3rd Presidential Debate of Obama and McCain meet the academic standards for arguments? Why or why not?

Definitely, the 3rd U.S. Presidential Debate is dissimilar from academic debates since the latter essentially requires speed. The key is to make as many arguments and present as much evidence to back them up as possible, before the clock runs out. Then you go down, point by point, and try to refute as many of your opponent’s arguments as you can. A judge assigns points to each side on that basis. According to Adrienne Christiansen, it is really an assessment of the kinds of evidence and arguments that are brought forward. 1

Whereas academic debates are a battle of ideas, presidential debates are a battle between two individuals. “They’re not trying to convince their opponent,” said Christiansen, “They’re not trying to disprove their opponent. They’re simply trying to take their position, and make it look interesting and clever and insightful to the moderator and to the television audience.” 2

However, in reference to the question --- technically, the essential requisites of arguments and academic standards for arguments were undoubtedly met despite of negligible violations made by the participants at the focal point of the debate (such as ignoring the time allocation for each participant per question as John McCain did most of the time), likewise, taking into account that all debates are forms of argumentation. 3

The folowing are the reasons and instances affirming my above-contention: Firstly, at the outset of the 3rd Presidential debate the host-moderator laid down rules in presenting their arguments and evidences thus making it a formal controversy not a mere verbal wrangling and evidently making it an art, of which argumentation is being referred.4 Secondly, in most instances, the candidates publicized their propositions by directing their words to the reasoning faculty and through appealing to emotions, to the feelings, to the will of American people, which are precisely the methods of approach in the work of argumentation. Lastly, though the issues or propositions were in a form a question raised by the moderator at certain point of time, the participants were able to manifest their claims duly supported with data or grounds and by presenting or citing concrete evidence, such as when Barak Obama cited his associates to warrant his claim against the alleged dishonorable, disrespectful campaign towards John McCain. Therefore, the key components of an argument were completely present in this debate thus making this debate in conformity with the academic standards for arguments.

Most importantly, even though presidential debates lack the logical rigor of an academic debate, they’re still extremely valuable part of the election season – one of the few times voters can evaluate the two candidates side-by-side.

Moreover, presidential debates aimed at helping people to decide who they want to vote for in the presidential election. Debating helps people choose which candidate to vote for by giving information on what candidates with logical facts, rather than physical appearance. This is extremely structured so that the candidates get equal representation. With this in mind, voters will base their vote on how well candidate represents their point of view. This does not necessarily lead to the best candidate being elected, but it does provide information.


1] Adrienne Christiansen , was the head debate coach at the University of Minnesota. Professor at St. Paul’s Macalester College, and studies political rhetoric.

2] –ditto-

3]A. Craig Baird, Pub. Discussion and Debate p. 8

4] Africa, The Art of Argumentation and Debate p. 6

Wednesday, November 26, 2008


What is an argument?

In philosophy, by 'argument' we mean 'something which attempts to prove from starting premises the truth of a conclusion'. Let us define the terms in the above definition.

'To Prove' means to compel belief rationally. If something is proved, then I have no choice, as a reasonable person, but to believe it - otherwise I am not rational. For our purposes, 'rationally' here means 'logical'. It does not mean to persuade by violence, trickery, bribery, rhetoric, emotion, etc. Thus, if I use rhetorical tricks of language to persuade my reader - for example, if I use flowery or showy language to make something sound good - then this is not proof. Again, if I merely appeal to the emotions of my reader, then this too is not proof; for example, describing the pain and suffering inflicted upon one group of people by the act of another may elicit sympathy, but does not necessarily mean that the act was morally wrong.

The premises are any statements that we have to make which are not themselves proven at the moment. (At the moment - they may in fact be the conclusions of previous arguments!) Premises may be incontrovertible pieces of knowledge; or they may be hypotheses that we make 'for the sake of argument...' For the argument to be considered successful, all these premises must be (although they may not be initially) clearly stated. No verbal trickery; no rhetorical persuasion; no appeals to that which is outside of reason.

The conclusion is whatever proposition the argument is attempting to prove. The conclusion may then be used as a premise in a later argument.

Formal and informal arguments

Informal arguments are studied in informal logic, are presented in ordinary language and are intended for everyday discourse. Conversely, formal arguments are studied in formal logic (historically called symbolic logic, more commonly referred to as mathematical logic today) and are expressed in a formal language. Informal logic may be said to emphasize the study of argumentation, whereas formal logic emphasizes implication and inference. Informal arguments are sometimes implicit. That is, the logical structure – the relationship of claims, premises, warrants, relations of implication, and conclusion – is not always spelled out and immediately visible and must sometimes be made explicit by analysis.

Deductive arguments

A deductive argument is one which, if valid, has a conclusion that is entailed by its premises. In other words, the truth of the conclusion is a logical consequence of the premises--if the premises are true, then the conclusion must be true. It would be self-contradictory to assert the premises and deny the conclusion, because the negation of the conclusion is contradictory to the truth of the premises.


Arguments may be either valid or invalid. If an argument is valid, and its premises are true, the conclusion must be true: a valid argument cannot have true premises and a false conclusion.

The validity of an argument depends, however, not on the actual truth or falsity of its premises and conclusions, but solely on whether or not the argument has a valid logical form. The validity of an argument is not a guarantee of the truth of its conclusion. A valid argument may have false premises and a false conclusion.

Logic seeks to discover the valid forms, the forms that make arguments valid arguments. An argument form is valid if and only if all arguments of that form are valid. Since the validity of an argument depends on its form, an argument can be shown to be invalid by showing that its form is invalid, and this can be done by giving another argument of the same form that has true premises but a false conclusion. In informal logic this is called a counter argument.

The form of argument can be shown by the use of symbols. For each argument form, there is a corresponding statement form, called a corresponding conditional, and an argument form is valid if and only its corresponding conditional is a logical truth. A statement form which is logically true is also said to be a valid statement form. A statement form is a logical truth if it is true under all interpretations. A statement form can be shown to be a logical truth by either (a) showing that it is a tautology or (b) by means of a proof procedure.

The corresponding conditional, of a valid argument is a necessary truth (true in all possible worlds) and so we might say that the conclusion necessarily follows from the premises, or follows of logical necessity. The conclusion of a valid argument is not necessarily true, it depends on whether the premises are true. The conclusion of a valid argument need not be a necessary truth: if it were so, it would be so independently of the premises.

For example: Some Greeks are logicians, therefore some logicians are Greeks: Valid argument; it would be self-contradictory to admit that some Greeks are logicians but deny that some (any) logicans are Greeks.

All Greeks are human and All humans are mortal therefore All Greeks are mortal. : Valid argument; if the premises are true the conclusion must be true.

Some Greeks are logicians and some logician are tiresome therefore some Greeks are tiresome. Invalid argument: the tiresome logicians might all be Romans!

Either we are all doomed or we are all saved; we are not all saved therefore we are all doomed. Valid argument; the premises entail the conclusion. (Remember that does not mean the conclusion has to be true, only if the premisses are true, and perhaps they are not, perhaps some people are saved and some people are doomed, and perhaps some neither saved nor doomed!)

Arguments can be invalid for a variety of reasons. There are well-established patterns of reasoning that render arguments that follow them invalid; these patterns are known as logical fallacies.


A sound argument is a valid argument with true premises. A sound argument, being both valid and having true premises, must have a true conclusion. Some authors (especially in earlier literature) use the term sound as synonymous with valid.

Inductive arguments

Inductive logic is the process of reasoning in which the premises of an argument are believed to support the conclusion but do not entail it. Induction is a form of reasoning that makes generalizations based on individual instances.

Mathematical induction should not be misconstrued as a form of inductive reasoning, which is considered non-rigorous in mathematics.In spite of the name, mathematical induction is a form of deductive reasoning and is fully rigorous.

Cogent arguments

An argument is cogent if and only if the truth of the argument's premises would render the truth of the conclusion probable (i.e., the argument is strong), and the argument's premises are, in fact, true. Cogency can be considered inductive logic's analogue to deductive logic's "soundness."

Fallacies and non arguments

A fallacy is an invalid argument that appears valid, or a valid argument with disguised assumptions. First the premises and the conclusion must be statements, capable of being true and false. Secondly it must be asserted that the conclusion follows from the premises. In English the words therefore, so, because and hence typically separate the premises from the conclusion of an argument, but this is not necessarily so. Thus: Socrates is a man, all men are mortal therefore Socrates is mortal is clearly an argument (a valid one at that), because it is clear it is asserted that that Socrates is mortal follows from the preceding statements. However I was thirsty and therefore I drank is NOT an argument, despite its appearance. It is not being claimed that I drank is logically entailed by I was thirsty. The therefore in this sentence indicates for that reason not it follows that.

Elliptical arguments

Often an argument is invalid because there is a missing premise the supply of which would make it valid. Speakers and writers will often leave out a strictly necessary premise in their reasonings if it is widely accepted and the writer does not wish to state the blindingly obvious. Example: Iron is a metal therefore it will expand when heated. (Missing premise: all metals expand when heated). On the other hand a seemingly valid argument may be found to lack a premise – a ‘hidden assumption’ – which if highlighted can show a fault in reasoning. Example: A witness reasoned: Nobody came out the front door except the milkman therefore the murderer must have left by the back door. (Hidden assumption- the milkman was not the murderer).

Rhetoric, dialectic, and argumentative dialogue

Whereas formal arguments are static, such as one might find in a textbook or research article, argumentative dialogue is dynamic. It serves as a published record of justification for an assertion. Arguments can also be interactive, with the proposer and the interlocutor having a symmetrical relationship. The premises are discussed, as well the validity of the intermediate inferences.

Dialectic is controversy, that is, the exchange of arguments and counter-arguments respectively advocating propositions. The outcome of the exercise might not simply be the refutation of one of the relevant points of view, but a synthesis or combination of the opposing assertions, or at least a qualitative transformation in the direction of the dialogue.

Argumentation theory

Argumentation theory, (or argumentation) embraces the arts and sciences of civil debate, dialogue, conversation, and persuasion. It studies rules of inference, logic, and procedural rules in both artificial and real world settings. Argumentation is concerned primarily with reaching conclusions through logical reasoning, that is, claims based on premises.

Arguments in various disciplines

Statements are put forward as arguments in all disciplines and all walks of life. Logic is concerned with what constitutes an argument and what are the forms of valid arguments in all interpretations and hence in all disciplines, the subject matter being irrelevant. There are not different valid forms of argument in different subjects.
Arguments as they appear in science and mathematics (and other subjects) do not usually follow strict proof procedures; typically they are elliptical arguments (q.v.) and the rules of inference are implicit rather than explicit. An argument can be loosely said to be valid if it can be shown that, with the supply of the missing premises it has a valid argument form and demonstrateable by an accepted proof procedure.

Mathematical arguments

The basis of mathematical truth has been the subject of long debate. Frege in particular sought to demonstrate (see Gottlob Frege, The Foundations of Arithemetic, 1884, and Logicism in Philosophy of mathematics) that arithmetical truths can be derived from purely logical axioms and therefore are, in the end, logical truths. The project was developed by Russell and Whitehead in their Principia Mathematica. If an argument can be cast in the form of sentences in Symbolic Logic, then it can be tested by the application of accepted proof procedures. This has been carried out for Arithmetic using Peano axioms. Be that as it may, an argument in Mathematics, as in any other discipline, can be considered valid just in case it can be shown to be of a form such that it cannot have true premises and a false conclusion.

Legal arguments

Legal arguments (or oral arguments) are spoken presentations to a judge or appellate court by a lawyer (or parties when representing themselves) of the legal reasons why they should prevail. Oral argument at the appellate level accompanies written briefs, which also advance the argument of each party in the legal dispute. A closing argument (or summation) is the concluding statement of each party's counsel (often called an attorney in the United States) reiterating the important arguments for the trier of fact, often the jury, in a court case. A closing argument occurs after the presentation of evidence.

Political arguments

A political argument is an instance of a logical argument applied to politics. Political arguments are used by academics, media pundits, candidates for political office and government officials. Political arguments are also used by citizens in ordinary interactions to comment about and understand political events.


^ Ayer, A. J., & O'Grady, J. (1992). A dictionary of philosophical quotations. Oxford, UK: Blackwell Publishers. Page 484.
^ McTaggart, J. M. E. (1964). A commentary on Hegel's logic. New York: Russell & Russell. Page 11
Robert Audi, Epistemology, Routledge, 1998. Particularly relevant is Chapter 6, which explores the relationship between knowledge, inference and argument.
J. L. Austin How to Do Things With Words, Oxford University Press, 1976.
H. P. Grice, Logic and Conversation in The Logic of Grammar, Dickenson, 1975.
Vincent F. Hendricks, Thought 2 Talk: A Crash Course in Reflection and Expression, New York: Automatic Press / VIP, 2005, ISBN 87-991013-7-8
R. A. DeMillo, R. J. Lipton and A. J. Perlis, Social Processes and Proofs of Theorems and Programs, Communications of the ACM, Vol. 22, No. 5, 1979. A classic article on the social process of acceptance of proofs in mathematics.
Yu. Manin, A Course in Mathematical Logic, Springer Verlag, 1977. A mathematical view of logic. This book is different from most books on mathematical logic in that it emphasizes the mathematics of logic, as opposed to the formal structure of logic.
Ch. Perelman and L. Olbrechts-Tyteca, The New Rhetoric, Notre Dame, 1970. This classic was originally published in French in 1958.
Henri Poincaré, Science and Hypothesis, Dover Publications, 1952
Frans van Eemeren and Rob Grootendorst, Speech Acts in Argumentative Discussions, Foris Publications, 1984. K. R. Popper Objective Knowledge; An Evolutionary Approach, Oxford: Clarendon Press, 1972

Sunday, November 23, 2008

Rules on an Oxford-Oregon Debate:

Format of Debate - Oxford-Oregon Type

Three Speakers from each side

First Affirmative - Constructive Speech
First Negative - Interpellation of the first affirmative Speaker
First Negative - Constructive Speech
First Affirmative - Interpellation of the first negative speaker
Second Affirmative - Constructive Speech
Second Negative - Interpellation of the second affirmative
Second Negative - Constructive
Second Affirmative - Interpellation of the second negative
Third Affirmative - Constructive Speech
Third Negative - Interpellation of the third affirmative
Third Negative - Constructive Speech
Third Affirmative - Interpellation of the third negative

Rebuttal of the Team Captain of the Negative Side
Rebuttal of the Team Captain of the Affirmative Side


Constructive Speech: Minimum of five (5) and maximum of seven (7) minutes
Interpellation: Five (5) minutes
Rebuttal Speech: Three (3) minutes

Issues for Debate

A. Whether or not it is Necessary? (Necessity)
B. Whether or not it is Beneficial? (Beneficiality)
C. Whether or not it is practical? (Practicability)

Criteria for Judging

A. Evidence - 25%
B. Delivery - 30%
C. Interpellation - 30%
D. Rebuttal - 15%

The judges, based on their discretion, shall have the authority to determine who will be the Best Speaker and Best Debater. The winning team shall be determined by the majority decision of the Board of Judges.

Guides for Constructive Speech

Speech types of Constructive Speech may be:

1. Reading Method
2. Memory Method
3. Extemporaneous
4. Mix method of memory and conversational or dramatic

Poise, gestures, audience contact and voice projection are highly recommended.

Rules on Interpellation

1. Questions should primarily focused on arguments developed in the speech of your opponent. However, matters relevant and material to the proposition are admissible.
2. Questioner and opponent should treat each other with courtesy.
3. Both speakers stand and face the audience during the question or Interpellation period.
4. Once the questioning has begun, neither the questioner nor his opponent may consult a colleague. Consultation should be done before but as quietly as possible.
5. Questioners should ask brief and easily understandable question. Answers should equally be brief. Categorical questions answerable by yes or no is allowed, however, opponent if he choose, may qualify his answer why yes or why no.
6. Questioner may not cut off a reasonable and qualifying answer, but he may cut off a vervous response with a statement such as a “thank you” “that is enough information” or “your point is quite clear” or “I’m satisfied.”
7. A questioner should not comment on the response of his opponent.
8. Your opponent may refuse to answer ambiguous, irrelevant or loaded questions by asking the questioner to rephrase or reform his question.

Rules on Rebuttal Speech

A. Rebuttal speaker should point out clearly the fallacies committed by his opponent stating clearly what particularly statement or argument constitute said fallacy.
B. If not familiar with the fallacies of logic, the debater may counter arguments directly by stating what arguments or statement is incorrect or false.

Role of the Moderator

The moderator of the debate has the following duties:

1. To reveal the issue involve the debate;
2. To rule on points of clarification about the issues or questions and answers made during the Interpellation; and
3. To see to it that the debate is orderly and follows the rules of parliamentary procedures.

Role of the Timer

1. To time the speakers and debaters accurately;
2. To give the speakers a one-minute warning with the ringing of the bell once before his/her time is up.
3. To prevent the debaters from exceeding the time allotted to them by ringing the bell twice.

Tips on Interpellation and Rebuttal


The cross-examination period of a debate is a time when the person who is not going to speak next in the constructives questions the person who has just finished speaking. Consider cross examination an information exchange period - it is not the time to role play lawyer.

Cross examination may serve six objectives:

  1. To clarify points
  2. To expose errors
  3. To obtain admissions
  4. To setup arguments
  5. To save prep time
  6. To show the judge how cool you are so they WANT to vote for you.

Most debaters tend to ignore the value of good cross-examination. Remember, 30% of the entire debate is spent in cross-examination -- it should be a meaningful and essential part of the debate. If nothing else, debaters tend to underestimate the importance that cross-examination may have on the judge. Cross-examination will indicate to the judge just how sharp and spontaneous the debaters are. Invisible bias will always occur in a debate round and judges would always like the sharpest team to win. Good, effective cross-examination of the opponents can play an important psychological role in winning the ballot of the judge.

Be dynamic. Have questions and be ready to go, answer questions actively and with confidence whenever you can. The image you project will be very important to the audience/judge. This is the one opportunity the audience/judge has to compare you with opponents side-by-side.


1. Ask a short Q designed to get a short A
2. Indicate the object of your Q
3. Don't telegraph your argument, don't make it too obvious.
4. Don't ask Q they won't answer properly."So, we win, right?"
5. Make Q seem important, even if it is just an attempt to clarify.
6. Politeness is a must -- emphasize the difference if they are rude.
7. Approach things from a non-obvious direction. Then trap them.
8. Mark your flow/notes as to what you want to question them about.
9. Avoid open ended Qs unless you are sure they are clueless.
10. Face the judge/audience, not your opponent.
11. CX answers must be integrated into your arguments made during a speech.


1. Concise A.
2. Refer to something you have already said whenever possible. This is safe.
3. Answer based on your position in the debate so far. Keep options open.
4. Don't make promises of what you or your partner will do later.
5. Qualify your answers.
6. Be willing to exchange documents read into the debate.
7. Answer only relevant questions.
8. Address the judge.
9. Try and not answer hypothetical Q. If they demand, say you will give a hypothetical A.
10. Signal each other, don't tag-team.
11. Don't say"I don't know,"say"I am not sure at this time...."


Most debaters, coaches, and judges would agree that rebuttals are the most difficult and yet the most important parts of the debate. Not only is there less time within each speech, but each debater has to sort through all of the issues to determine which ones are the most important ones! What a debater does or does not do in rebuttals will decide who wins the debate. Very few debaters (especially beginners) can hope to extend everything that happened in the constructive speeches. Debaters don't have to do that and just because a team may have dropped a point or an argument is not an automatic reason to vote against that team. What matters is the type of argument that is extended or dropped in rebuttals-this will determine the winner of the round.

Think about these four issues when rebuttals happen:

1. Which arguments have more weight at the end of the round?
2. Which outcomes (disads, counterplans) are more likely given lots of internal links?
3. What about time frame-what happens first?
4. What about the quality of evidence?

Here are some other helpful hints:

1. Avoid repetition. Don't just repeat your constructive arguments. Beat the other team's arguments and tell the judge why your arguments are better.

2. Avoid passing ships. Don't avoid what the other team said. You must clash directly with their responses.

3. Avoid reading evidence only. You must be explaining and telling the judge why these issues win the debate.

4. Avoid rereading evidence that has already been read in constructives. You can make reference to it by referring to it, but don't re-read it.

5. Avoid"lumping and dumping."Don't try to go for everything. You can't make 12 responses to each argument in a few minutes.

6. Be organized. Don't jump from issue to issue at random. Be specific and logical about winning issues.

7. Don't be a blabbering motormouth. Speak quickly but not beyond your ability. If you speak too fast, you will stumble and not get through as much.

8. Don't whine to the judge about fairness or what the other team might have done that you think is unethical. Make responses and beat them.

9. Don't make new arguments. You can read new evidence but you can't run new disadvantages or topicality responses. You are limiting to extending the positions laid out in the constructive speeches.

10. Use signposting . Make sure the judge knows where you are on the flowsheet. This is not the time to lose the judge on the flow.

11. Use issue packages. Organize your arguments into issue packages. Choose arguments which you want to win. Don't go for everything. Extend those arguments that you need to win.

12. Cross-apply arguments. If you dropped an argument in a prior speech that you think was important don't act like your losing. Cross-apply arguments you made somewhere else in the debate to answer it.