Argument

An argument is a connected series of statements or propositions, some of which are intended to provide support, justification or evidence for the truth of another statement or proposition. Arguments consist of one or more premises and a conclusion. The premises are those statements that are taken to provide the support or evidence; the conclusion is that which the premises allegedly support. For example, the following is an argument:

The death penalty should be adopted only if it deters murder. However, it could only do this if murderers understood the consequences of their actions before acting, and since this is not so, we must reject adopting the death penalty.

The conclusion of this argument is the final statement: “we must reject reject adopting the death penalty.” The other statements are the premises; they are offered as reasons or justification for this claim. The premises of an argument are sometimes also called the “data,” the “grounds” or the “backup” given for accepting the conclusion.

Because arguments are attempts to provide evidence or support for a certain claim, they often contain words such as “therefore,” “thus,” “hence,” “consequently,” or “so” before their conclusions. Similarly, words or expressions such as “because,” “inasmuch as,” “since,” “for the reason that,” etc., are often found accompanying the premises of an argument. Such “indicators” can aid in the task of identifying the conclusion of the argument, which often comes last in the series of statements making up the argument, as in the example above, but can also come first, or even in the middle, such as in these examples:

Councilwoman Radcliffe is the best person for the job. This is because she has the most legislative experience of all the candidates, and she will not place the interests of corporations above those of the people.

Callisto orbits Jupiter. Hence, it is not a planet, because something must orbit a star in order to be a planet.

In the examples above, the italicized statements are the conclusions. The other statements are offered as reasons or justifications for these claims.

In everyday life, we often use the word “argument” to mean a verbal dispute or disagreement. This is not the way this word is usually used in philosophy. However, the two uses are related. Normally, when two people verbally disagree with each other, each person attempts to convince the other that his or her viewpoint is the right one. Unless he or she merely results to name calling or threats, he or she typically presents an argument for his or her position, in the sense described above. In philosophy, “arguments” are those statements a person makes in the attempt to convince someone of something, or present reasons for accepting a given conclusion.

In normal conversation, certain important elements of an argument might be left implicit or unstated. In the last example given above, the person advancing the argument most likely takes it for granted that his or her audience understands that if something orbits Jupiter, then it does not orbit a star. This supposition is a vital part of the evidence or support that the author intends the stated premises to provide for the conclusion. Here, the statement “if something orbits Jupiter, then it does not orbit a star” is operating as an implicit or unstated premise. Therefore, the above argument is best understood as an abbreviated form of the full argument:

Callisto orbits Jupiter. Something must orbit a star in order to be a planet. If something orbits Jupiter, then it does not orbit a star. Therefore, Callisto is not a planet.

Even the conclusion of an argument can be left unstated if it is obvious enough from context that the speaker intends his or her words to provide evidence for a certain proposition. Consider, for instance:

Only children are allowed on the swingset, and Ms. Peabody, you are no child, are you?

Here, the speaker is obviously inviting Ms. Peabody to draw the conclusion that she is not allowed on the swingset.

Normally, a single statement in isolation does not constitute an argument, but simply a declaration or assertion. For example, if a teacher simply announces at the beginning of a class “Councilwoman Radcliffe voted in favor of the tax increase,” she is not arguing for a given conclusion; she simply intends her students to accept her assertion on its own. However, in the right context, a single statement can abbreviate a whole argument if the other implicit pieces of the argument are clear from the context. In a discussion among conservative politicians discussing whom they’d like to see as the next candidate for Senator, where it is agreed by all participants that no one who supports increased taxes is a desirable candidate, someone might implicitly be arguing against Radcliffe’s candidacy with the simple statement, “Councilwoman Radcliffe voted in favor of the tax increase.” When the implicit premise and implicit conclusion are filled in, the argument in its entirety could be stated in this way:

Councilwoman Radcliffe voted in favor of the tax increase. No one who voted in favor of the tax increase is a desirable candidate. Therefore, Councilwoman Radcliffe is not a desirable candidate.

In an argument, the premises are almost always put forth or claimed to provide support for the conclusion; however, the premises do not always actually provide support. If we take as our example the following argument:

The roulette wheel has landed on red the last five spins. Therefore, since black is “due,” the next spin will probably be black.

The person stating this argument probably thinks that the conclusion is justified by the premise, but he or she would be mistaken. The reasoning here is fallacious. The premise could be true without the conclusion being definitely or even probably true. However, this is still an argument, because the premise is at least intended to provide support or evidence for the conclusion, even if it does not.

Logicians study the criteria to be used in evaluating arguments, i.e., the criteria for determining under what conditions a certain set of premises actually guarantees the truth or likely truth of the conclusion.

Arguments are related to inference and reasoning: i.e., the psychological process through which a person forms a new belief on the basis other beliefs. A course of reasoning can usually be recast or reconstructed as an argument. For example, if someone already believed that all Romance languages were derived from Latin, and then learned that Rumanian was a Romance language, she or he would likely form the new belief that Rumanian was derived from Latin. If this person were to express her or his train of thought out loud or write it down, it would take the form of this argument:

All Romance Languages are derived from Latin. Rumanian is a Romance Language. Therefore, Rumanian is derived from Latin.

However, it should not be thought that the psychological process of inference or the nature of cognition are relevant to the evaluation of arguments. Regardless of whether or not the argument above corresponds to anyone’s psychological process or cognitive behavior, it can be analyed by logicians as valid, because the premises do provide support for the conclusion.

Arguments must be separated off from other uses of language, such as to explain something, give an example, or tell a story. In these cases, one might find a connected series of statements, but the author or speaker does not intend it to be the case that some of them provide support or evidence in favor of one of the others. So they are not arguments. Consequently, one must distinguish arguments fromreports of arguments. If a newspaper journalist includes in her article a description of an argument given by Senator Feingold in favor of campaign finance reform, the reporter is not herself arguing in favor of campaign finance reform nor anything else. She is merely making a report.

There are other uses of language that may appear at first blush to be arguments, but are not. Such is the case with explanations. Sometimes it is agreed by participants in a conversation that a certain event has taken place, or that a certain thing is true. Suppose, for example, it is agreed that Alex is late for his job. Someone might explain this fact as follows:

Alex’s car broke down yesterday, and without it he cannot get to work on time. Therefore, he is late for work today.

The above may appear to be an argument. In fact, it has the same structure as an argument, and even includes the indicator “therefore.” However, notice that the person speaking these words is not attempting to provide support or evidence for the truth of the claim that “Alex is late for work today:” that is already accepted as true in this context by everyone involved. Properly speaking, the above example is an explanation, not an argument. However, in another context, in which it was not generally known that Alex is late for work today, these very words could be used as an argument. Consequently, it is impossible to ascertain whether or not a certain utterance is an argument without ascertaining the speaker’s intentions within the given context. (For more on the relationship between arguments and explanation, see the article on “Scientific Explanation.”)

Much of philosophy consists in the evaluation of particular arguments, some simple, some complicated. Descartes’s famous three word saying, “cogito ergo sum” (I think, therefore I am) represents an extremely compact argument, with a single premise, that he is thinking, to the conclusion that he exists. Other philosophical arguments are more complicated and elaborate. Consider the following argument from Plato’s Apology:

Let us reflect in another way, and we shall see that there is great reason to hope that death is a good, for one of two things: — either death is a state of nothingness and utter unconsciousness, or, as men say, there is a change and migration of the soul from this world to another. Now if you suppose that there is no consciousness, but a sleep like the sleep of him who is undisturbed even by the sight of dreams, death will be an unspeakable gain. For if a person were to select the night in which his sleep was undisturbed even by dreams, and were to compare with this the other days and nights of his life, and then were to tell us how many days and nights he had passed in the course of his life better and more pleasantly than this one, I think that any man, I will not say a private man, but even the great king, will not find many such days or nights, when compared with the others. Now if death is like this, I say that to die is gain; for eternity is then only a single night. But if death is the journey to another place, and there, as men say, all the dead are, what good, O my friends and judges, can be greater than this? If indeed when the pilgrim arrives in the world below, he is delivered from the professors of justice in this world, and finds the true judges who are said to give judgment there, Minos and Rhadamanthus and Aeacus and Triptolemus, and other sons of God who were righteous in their own life, that pilgrimage will be worth making. What would not a man give if he might converse with Orpheus and Musaeus and Hesiod and Homer? Nay, if this be true, let me die again and again.

Here the character Socrates argues for the conclusion that death is a good. The justification he offers for the conclusion, however, is rather elaborate; he offers quite a few premises, which, taken together, are thought to provide support for the conclusion.

Note: There is another, completely distinct, use of the word “argument,” that can also be relevant to logic, specifically, to the logic of functions and relations. An argument to a function is contrasted with the value of that function. Loosely speaking, the argument is the input, the value is the output. When the square root function takes 9 “as argument,” the value is 3. When it takes 16 “as argument,” the value is 4. Different functions take a different number of arguments. The square root function takes a single argument; whereas addition and multiplication require two arguments to yield a value. I.e., in the equation, x + y = z, x and y are the arguments to the addition function, and z is the value. Sometimes, logicians also speak of predicates and relations as having a certain number of “argument-places.” For example, the relation expression “___ is taller than …” is said to have two argument places, because it requires completion by two terms to form a complete proposition.

See also the articles on Deductive and Inductive Arguments, Validity and Soundness, Propositional Logic, and Fallacies in this encyclopedia.