We have now arrived at what is perhaps the most important and most difficult part of disagreeing well: the arguments. Arguments can take the form of a series of propositions that are linked together in such a way so as to demonstrate in a logically cohesive manner that a proposition is true. Again, I must avoid getting into formal logic here, for that indeed would take much more time and discussion (and I yet have much to learn about formal logic myself, for I am by no means an expert).
Many logicians debate to this day whether it is even possible to fully demonstrate the truth of a proposition. I cannot hope to even clarify the debate here. What I can say is that in our everyday conversation and debate with others, we should be careful to at least make arguments that are as logically cohesive as we can possibly make them (although this, too, brings up a difficulty involving the issue of rhetoric, but that is also a topic for another time).
One of the fundamental tenets of logic is asking the question, “What follows from what? If X is true, then what follows as a consequence of X being true?” Depending on the nature of X, we can theoretically determine what follows from X. It just so happens that all living human beings will die. This enables us to say that if I am being a human being (we can only assume), then I will die. If we label my being a human being as X, and all human beings die as Y, then we can say that Y follows from X: If I am a human being, then I will die.
Now, when it comes to argumentation, not all arguments will be as logically demonstrable as this. There will be some propositions and/or premises that will more-or-less follow from the preceding premises, and in some cases, will not at all follow from the premises. There may be conclusions that do not follow from the premises. This does not mean that the conclusion is necessarily false; it just means that it does not logically follow from the premises; wherefore, the argument does not validly support the conclusion. It could be that a true conclusion is supported by false premises, which would mean that the conclusion does not follow from the premises.
Let us consider an example of bad logic: All animals that live in water are fish. A whale lives in water; therefore, a whale is a fish. We can see that the conclusion does not follow from the premises. This is because the whole argument is based on a false premise: all animals that live in water are fish. The only true premise is the statement “All whales live in water.” In this case, the faulty logic is easy to see, as we don’t really need to demonstrate that a whale is necessarily a fish (although I suppose this could be debated, for we who are students of philosophy never miss an opportunity to debate utterly bizarre issues).
In other cases—in most cases, even—it will be more difficult to identify a false proposition or premise that does not follow from the preceding premise(s). For example, if I were to make the proposition, “Lowering taxes will improve the economy,” I might support this proposition by arguing that lowering taxes will increase the amount of money that the average citizen will have. If the average citizen has more money, then she will most likely spend more money. If more citizens spend more money, then more businesses will have more money. I could go on, but you get the idea, so I’ll just proceed with the hypothetical conclusion, which is that lowering taxes will improve the economy.
Notwithstanding my apparent need to establish what I mean by such terms as “economy” and “improve,” I simply do not have enough data from my argument alone to demonstrate that my conclusion follows from the premises. The major difficulty with this argument, if I am show you that my initial proposition is true, is to (1) show that my premises are true, (2) show that my premises and conclusion logically follow from one another, and (3) show that that conclusion follows from the premises.
Now, if you make it your task to show the faults in my argument, you must show wherein the conclusion does not follow from the premises, the premises are false, or the conclusion is false. To prove that the premises are true or false will require a bit of additional research, as there is simply not enough information in the premises themselves to show that they are either true or false. The same can be said of the conclusion. And you must note that it is still theoretically possible for some of the premises to be false while the conclusion is true. If such were the case, it would mean that I have not argued my case well.
It can also be the case that the premises may all be true, with each one following from the other, but the conclusion is false. Again, this is just something that would only show my poor logical skills. When it comes to doing such things in your everyday discourse with others, recognizing such things will take practice and study, as there is so much more to logical reasoning. And I have, in any case, probably done a terrible disservice to formal logic with my rather brief exposition here of some of its central tenets.
But now that I have explained such things, I suspect I am in a good position to explain just when it is that we might have “good reason” for disagreeing with someone. First and foremost, we cannot have good reason to say that we disagree with someone’s argument if we do not fully understand it. Doing so would be like grading a student’s math test when the person grading does not himself have a full understanding of how to do the test.
If you do not fully understand your interlocutor, you may end up criticizing her for a point she may or may not have made, or you will incorrectly criticize her arguments because you thought she was saying one thing, when in reality she was saying something different. Once again, you cannot say that you understand someone’s position unless you understand their relevant terms, propositions, and arguments.
Once you feel confident that you do understand your interlocutor’s position, then you can make your judgement as to whether or not what she said was true. And it could be that you only find a part of what she said to be true while the rest is false, or vice versa. You do not have to speak in absolute terms when stating whether you find someone’s position to be either true or false, as not all arguments (or conclusions) are wholly true or wholly false.
Once you have made your judgement, stating that you disagree with your interlocutor because you find her conclusion(s) to be false, you must then be able to show why you disagree. This is akin to showing your work on a math exam. A math teacher cannot be confident that his student fully understands the material if the student can write the correct answer to a question but not fully show his work in finding the right answer. If you say, “I disagree” without being able to explain why you disagree, you are not making a statement based on truth; you are making a statement based on opinion, or your personal feelings. Personal feelings have no bearing on truth, for there is no way to demonstrate through personal feeling that an argument is true or false.
Adler and Van Doren explain that when you disagree with someone, you can only reasonably do so if you can show to your interlocutor at least one of four things: (1) he is uninformed, (2) he is misinformed, (3) he is not being wholly logical, or his argument is not fully cogent, and (4) his argument is not complete. These are the only reasonable grounds upon which you can disagree with someone’s argument. To be able to show wherein your interlocutor lacks or fails in any of these four criteria will give you good grounds for disagreeing with her. This is what I mean by having “good reason” to disagree with someone.
But the other side of this coin may be a bit disconcerting: if you cannot find any good reason for disagreeing with someone’s argument; if her logic is sound; if it does not lack in vital information; if the information given is not inaccurate or mistaken; if her analysis is complete; and if, perhaps most importantly, you fully understand her argument, then you should accept her argument as being true, and thereby adopt her position as your own.
The reason for this is simple: you have no good reason for disagreeing with her. Even if her arguments and conclusions are uncomfortable for you to accept; even if you have a gut feeling that she is wrong or that you should not accept her position, you still do not have good reason to reject her position. If you do have a gut feeling that her argument is mistaken in any way, you must be able to show why it is mistaken. Otherwise, you are just rejecting her position based on mere opinion, and mere opinion, as I stated before, has no bearing whatsoever on truth.
This concludes Part III. In the next part, we will take a more broad examination of the power of ideas, which will hopefully help you to understand the importance of disagreeing well and properly handling ideas.