A DISAGREEMENT IS NOT AN ARGUMENT

—The most common but least effective way to criticize an argument is simply to deny its conclusion:

"I feel that Socrates is mistaken. Just because Socrates believes that justice is necessary and sufficient for human happiness doesn't mean it is true. After all, what is just for one person might not be just for another. Further, happiness is so subjective that you simply cannot say that being a just person will always make you happy. So we should reject Socrates arguments against Thrasymachus' view that justice is neither necessary nor sufficient for happiness."

Merely disagreeing with someone fails to provide a sufficient reason for anyone to believe that what they claim is false or unacceptable. Other thinking people observing the disagreement will rarely be persuaded to accept your criticism as anything substantial if you do not provide further evidence to the contrary. And the person with whom you disagree will be unmoved by your attitude.

Assume that when someone produces an argument supporting a claim, they want to know what exactly is wrong with the REASONS FOR the conclusion offered; they do not want to hear that you just don't agree with that conclusion or that you happen to believe otherwise. No matter how passionately or loudly you reject any claim, just saying that someone is mistaken because they are wrong and you (or the Bible or Einstein) are right is the weakest way to make your case.

If you want to reveal that what someone asserts is not reasonable to believe, then you must introduce reasons against accepting the argument for his or her conclusion. You must produce credible REASONS AGAINST their REASONS FOR their conclusion, this is called making a rebuttal.

A REBUTTAL is an argument for rejecting the conclusion of another argument.

A rebuttal is directed against the presumptions of the rival argument.

Consider an argument in abstract terms, where P (which stands for a proposition describing evidence or an assumption) is some claim given in support of some further claim Q (namely the conclusion). The reasoning goes like this:

"If P then Q. P is true. Thus, Q is true."

 

Often when the essential but hypothetical assumption is left unstated, people will just say "Q is true since P is true." For example, "Mary should have an abortion since she does not want to raise another child."

Notice the legitimate logical rule of inference applied here, namely modus ponens, or the method of deriving the consequent by affirming the antecedent. But any rule of inference does not by itself guarantee that any conclusion is true. We must examine the claims comprising the conditional assumptions upon which these rules apply. Both claims, "If P then Q," and "P" must to be TRUE for logical rules to make a piece of reasoning worth accepting.

Consider the following:

Spock: "Given P, I conclude Q." Implicit assumption: {If P then Q.}

McCoy: "You are wrong, I say not-Q." (This response merely disagrees with Q.)

Kirk: "Whether Q is true depends upon one's perspective." (This response changes the subject.)

 

There are more sophisticated but equally lame responses:

Mr. Point: "Q is true because P is true." Implicit assumption: {If P then Q.}

Ms. Counterpoint: "But, just because P (is true) does not mean that Q (is true)." (This is just disagreement with Q.)

Dr. Contrarian: "It is not necessarily the case that Q is true because P is true." (This response changes the subject.)

Such responses only really amount to ignoring or rejecting the original argument which asserted that the reason for accepting Q is that P is true. The best way to undermine these original claims, should one choose to do so, is to attack the connection between P and Q. INTRODUCE DOUBT about what is assumed, namely, the conditional proposition "If P, then Q."

Two controversial arguments, one argues for a descriptive conclusion, the other argues for a normative conclusion.

EXAMPLE 1

    1. If scientific instruments do not detect a poisionous atmosphere on the unexplored planet, then it is safe to send a landing-party to that planet's surface. {If P then Q}
    2. Scientific instruments do not detect a poisonous atmosphere on the unexplored planet. {P}
    3. Therefore, it is safe to send a landing-party to that planet's surface. {Q}

EXAMPLE 2

  1. If Mary does not want to raise another child, then she should have an abortion. {If P then Q}
  2. Mary does not want to raise another child. {P}
  3. Therefore, she should have an abortion.{Q}

Common but weak rebuttal strategy: "Just because P doesn't mean Q." I.e., deny or reject Q by disagreeing with it. This is a start but only if you follow with Strategy A below.

Typical Reply to this weak denial: "So what (if you disagree) that's just your opinion, I'm right since you haven't proven me wrong."

Two Better Strategies for Effective Disagreement

Strategy A: If you want to deny that Q is true, then show that it doesn't matter whether P is true.

Demonstrate that Q could be FALSE even if P is TRUE. Do this by pointing out that the alleged connection between P and Q is not enough. Produce an example illustrating that P does not lead directly to Q. Describe how even if one assumes that P is true, something else is a definite possibility, and that possibility (being likely) makes all the difference. The difficulty here is showing that what is possible is actually very likely, that is show P could be true but Q false. For example, show that it has been so under similar circumstances in the past.

Example 1: Assume that Spock's scientific instruments do not detect a poisonous atmosphere on the planet (i.e., assume P). However, Spock's instruments also do not detect hostile, predatory, or disease-causing life-forms, and an encounter with any of these might prove fatal. In fact, this has happened numerous times in the history of inter-planetary exploration. Spock's instruments may have technical limitations on what they can detect or they may be malfunctioning; in either case P would be false and it would not be safe to send a landing-party. Your task is not merely to question the reliability Spock's instruments, you must DEMONSTRATE that the instruments are in fact limited or malfunctioning. So here are serious reasons to doubt that it is safe to send a landing party to the surface of the planet (i.e., Q).

Example 2: Assume that Mary does not want to raise another child (i.e., P). However, her not wanting another child does not stop another person from wanting to raise a child. Suppose she does not want another child but another person does and is willing to take and raise it as their own. Where adoption is possible and likely, a pregnant woman could choose not to raise another child and another person could choose to do so instead. So here is a serious reason to doubt that Mary should have an abortion (i.e., Q).

NOTE: In both of these examples we only demonstrate that P does not lead one straight to the conclusion that Q is true. We do not demonstrate that it is unsafe to send a landing party to the surface of an unexplored planet nor do we demonstrate that Mary should not have an abortion. All we need to do is to produce a reasonable doubt about Q. So long as this is exactly how a person has argued for his or her position, you have exposed a problem with their reasoning when you introduce what has been overlooked. Of, course, it is POSSIBLE that Q is true, but this is a different and far weaker claim than the claim that Q is ACTUALLY true. And we wanted to see whether what was assumed, namely P, sufficiently justified believing that Q is actually true.

 

 

Strategy B: Assume (for the sake of argument) that IF P is true then this makes Q true also. Then show that P is actually false. Thus, Q loses its support from P, so your opponent has to come up with another reason for Q.

Demonstrate that P is FALSE, even if Q is a consequence of P. Do this by testing any presumptions or observations that allegedly support P. There are many ways this could be done but accomplishing this requires an intense scrutiny of deeper underlying assumptions OR the ability to demonstrate that things are not as they appear. In effect, without P for support, the person with which one disagrees needs to produce a new argument for Q. By showing that the only evidence for Q is erroneous, Q becomes dubious.

 

Example 1: Perhaps Spock's instruments DO detect a toxic atmosphere but somehow Spock misreads their indications. In this case P would be false. Here you would have to demonstrate that Spock is hallucinating or delusional. Not an easy task, but if it could be shown that in this case his being unwell and unreliable is likely, then this would undermine the credibility of his reports and give one a good reason to doubt P. Given this circumstance, even if the pattern of reasoning from P to Q were acceptable, with P false, we could not conclude Q is true as a consequence of P. You can't get to Q via P.

Example 2: If you could somehow probe the psyche of the pregnant woman (Mary in the example above) who claims she does not want to raise another child and reveal that in fact she really does want another child but has serious misgivings (perhaps she is poor, has a non-supportive family or abusive spouse or doubts her ability to be a good parent) then you would show that P is false. This is easier said than done, but raising these deeper unsettled issues and getting a definite confirmation of Mary's actual belief (not-P) would definitely reveal that Q needs some other evidence to support it. Perhaps Q is true, but P is not a way to derive it. Again, you can't get to Q from P.

 

SUMMARY

Both strategies reveal that there are good reasons for doubting Q and this is what you have set out to do. In the first case, the reason your opponent gives in support of the conclusion is insufficient. You deny the conclusion because you SHOW that P does not obviously lead to Q, you do not simply say "Just because P does not mean Q." In the second case, the reason your opponent gives in support of the conclusion is unacceptable because that reason is demonstrably false. You thus deny the conclusion because you SHOW that P cannot lead to Q, since P is false. You do not simply say "You are mistaken because Q is wrong," what you say in effect is that "You are wrong because P is false, and if P leads to Q as you have said, you don't have P for support, so Q needs some other reason to support it, thus I do not accept Q for lack of evidence."

In logical terms, applying either of these strategies will drive a wedge between the antecedent circumstance and its alleged (but dubious) consequent. This blocks the move from P to Q and your disagreement is more likely to have a serious and useful objective effect, since it exposes a weakness in a chain of reasoning.

What such strategies do NOT do: Neither PROVES that the conclusion is false nor that the person with whom you disagree is wrong. But they do introduce reasonable doubt.

What such strategies do: Both PROVE that there are good reasons not to simply accept the conclusion offered on the basis of the problematical evidence (and argument) provided. Reasons NOT to believe are often more powerful persuaders than reasons to believe. The persistent lack of vital signs in the emergency room is a pretty good reason not to believe that there is any life left in the accident victim's body.

 

Suppose we want to believe (minimally) only reasonable or plausible claims: