Refutations of Arguments (and the Burden of Proof Principle)

§5.1

It is important to distinguish between refutations of arguments and refutations of propositions. A refutation of a proposition is a proof (or attempted proof) that the proposition is false. A refutation of an argument is a proof that the argument does not actually support its conclusion. The word “refutation” is usually reserved for cases in which the falsehood of the proposition or the badness of the argument is established conclusively. The word “counterargument” is a broader term for any argument that casts doubt on a proposition or argument.

Counterarguments to propositions are simply arguments that the propositions are false, and one assesses them just as one would any other argument. We will discuss later how to deal with situations in which there are arguments for and against the same proposition. I want to focus now refutations of arguments.

Most of this primer has been about evaluating arguments to determine how strongly, if at all, they support their conclusions, so you already know how to refute an argument or give a counterargument to it. An argument can be refuted by showing either that one of its premises is false or unfounded, or by showing that the conclusion does not follow from the premises. Doing either of these things would show that the argument provides no support for its conclusion. Weaker counterarguments would show that the argument supports its conclusion less strongly than might have been supposed by either showing that the premises have a lower epistemic status than supposed or that the inference is weaker than supposed.

Just as one must assess arguments, one must assess counterarguments, and there can be counterarguments in defense of the original arguments, and then further counterarguments to these, forming a sometimes elaborate back and forth. No doubt you’re familiar with this process from debates or the sorts of conversations that we ordinarily call “arguments”.

If an argument has been successfully refuted, then the epistemic status of the argument’s conclusion returns to what it would have been if the argument had never been given. Thus, if all the arguments in favor of a proposition have been refuted (assuming that all of our reasons to believe the proposition come from arguments) the proposition is unfounded.

In some cases, it may be possible to go on to prove that the proposition is false, but it is important to recognize that one does not need to do this in order to be justified in rejecting the proposition. This is an important principle of logic called “The Burden of Proof Principle” (or sometimes the “Onus of Proof Principle”). The principle states that the burden of proof is on the person who asserts a proposition. The point is usually made in the context of a debate between two people. If one of them makes a claim, then it is his responsibility to give the other person reasons to accept it, and the other person is not required to give reasons to reject it. The second person’s responsibility begins only after the first person has given such reasons. Once these reasons have been given, the second person must either then accept the proposition, or give some counterargument either to the first person’s argument or to the proposition itself. But though often formulated in the language of a debate between two parties the point applies equally well to a solitary person considering the epistemic status of a proposition: he needs a reason to regard it as certain, probable, or even possible; and, if unless he has some such reason, he needs no further argument in order to reject it as unfounded.

To appreciate the importance of the burden of proof, consider its application in the law, where it is familiar in the form of the slogan that a defendant is “presumed innocent until proven guilty”. When a prosecutor charges you with a crime, it is his responsibility to provide arguments that you are guilty. Once he has done so, your job (or your lawyer’s) is to refute those arguments. In some cases, you may be able to prove that you did not commit the crime—for example, you might produce witnesses who testify that you were elsewhere when the crime occurred—but you have no obligation to do so. If the prosecutor makes his charges arbitrarily, without supporting them with arguments, then it is a sufficient defense to simply point out that he has done so. And, if he does make arguments that you are guilty, it is sufficient to refute them.

Of course, in a criminal court, any counterargument good enough to show that there is a reasonable doubt about your guilt is sufficient for an acquittal. If this were the best you could do, however, people would rightly continue to think that you probably committed the crime. But, suppose that you entirely refuted the prosecutions’ arguments, showing that they provided no reason whatsoever to believe that you were guilty. Then, even if you provided no positive argument that you couldn’t have committed the crime, wouldn’t it be unreasonable and unjust for anyone to continue even to suspect you? Wouldn’t you have cleared your name?

You may be thinking that refuting the arguments for a proposition is good enough for most purposes, but that the matter remains unsettled until the proposition has been positively disproven. If so, consider the following point: if one was not entitled to dismiss unfounded propositions without argument, it would be impossible to disprove anything. Why not? Suppose that after being accused arbitrarily of committing a murder, you tried to prove your innocence producing witnesses who could testify that you were elsewhere when the murder was committed. Your accuser could respond by alleging, without any evidence, that the witnesses are accomplices. Even if you had a whole football stadium full of witnesses and time-stamped video footage (for example, if you were on the Jumbotron during a game), he could allege that they are all part of some vast conspiracy and that the footage is forged. Or he might say (again without any evidence) that you have an identical twin who was in the stadium, or that you have magic powers and are able to be in two places at once, or that you committed the murder remotely by telekinesis. If he is allowed to assert whatever he likes without giving reasons, and it cannot be dismissed until it is disproven, then no matter what arguments you give to disprove each assertion, he can always dream up further unfounded assertions that will allow him to maintain it, and then the matter won’t be settled until you disprove these new assertions. On the other hand, if you are entitled to dismiss his unfounded comebacks simply because they are unfounded, then you are entitled to dismiss his initial accusation on the same grounds.

Because the unfounded is to be dismissed, once all the arguments in favor of a proposition have been refuted, the proposition should be dismissed, even if there are no further arguments against it.

However, it must be emphasized that it is not legitimate to dismiss a proposition as unfounded until all of the arguments for it have been refuted. If there are multiple arguments, it is not sufficient to refute only some of them, and it is not sufficient to merely cast some doubt on the arguments with weak counterarguments. In situations in which many arguments have been offered for a proposition, the task of evaluating (and possibly refuting) all of them may seem daunting, but usually these arguments fall into families with similar structures, and the families can often be assessed as wholes. For example, as we will discuss in class, there have probably been thousands of distinct arguments offered over the centuries for the existence of God, but they are all variations of a handful of archetypical arguments. Thus, one needn’t assess each argument individually.