When you disagree with someone, there are a variety of ways to approach that disagreement. The most obvious kind of approach would be to ask someone why they disagree with you and what evidence they have that underlies the disagreement. After all, in order to have a productive conversation you need to be talking about the same thing! But even if everyone involved in a discussion is ‘on the same page’ in this way, there are still a variety of ways that disagreement might happen.
In order to best express these distinctions, it is helpful to give a simple definition of what we mean when we say we know something. There is debate in philosophy about what knowledge actually is and what qualifies as knowledge, but for my purpose here we will use the most ‘basic’ idea of what knowledge is. This will be called the JTB model for short – which stands for justified true belief. Here is the basic idea. When we talk about knowing something, we of course mean at least that we believe it. However, knowing and believing are not the same thing. After all, the way we normally use the word know is underpinned by the idea that what we know actually is the case – that it is true. So knowing something, at least, must mean having a true belief. But this is also not quite enough. You might have a true belief that your team will win the baseball game tomorrow, but if your team is a massive underdog, most people would say you are being irrational. This example shows that you need some kind of reason for knowing something, some kind of justification. Using the JTB model, once we have a justified true belief, we can now say that we know something.
The reason I bring up this model is because knowledge is a helpful framework within which to analyze a disagreement. Say you are arguing with your friend Sarah about X. Sarah says that she knows X, but you don’t believe X – that is, you think Sarah is in some form mistaken. Using the JTB way of thinking about Sarah’s claim to know X, we might ask what went wrong. Since Sarah is claiming to know X, surely Sarah believes X. There isn’t much reason (at least in normal situations) to question whether your friend is being honest about what they believe. So how are you going to go about your disagreement with Sarah?
When you bring reasons forward in disagreement with a person, these reasons are often called defeaters. Put another way, a defeater would be a new piece of information that is meant to convince you to change your mind about something that you know (or think you know). Defeaters are whatever someone might bring to you as counterevidence to what you already believe/know. In the disagreement with our friend, we are wanting to give Sarah some sort of defeater for something she believes and claims to know.
Option 1: Refutation (Attacking the T of JTB)
One straightforward way to disagree would be simply claiming that she is wrong. You could say that Sarah doesn’t actually know X because X isn’t even true. In this approach, you would try to bring forward reasons to convince Sarah of the falsehood of X. These approaches are collectively called refutations, or refuting defeaters. If Sarah becomes convinced of your refuting defeater, she will come to believe that X is false, and because your friend is an honest person, will stop believing X.
Option 2: Rebutting (Attacking the J of JTB)
There are other ways a person can be flawed in their thinking that are not necessarily about matters of truth or falsehood. You might just think your friend is being hasty or biased. This is the case with the example of the baseball game I used earlier. It could very well be true that the team will win the game, but it might not be a very reasonable thing to believe until it actually happens if the team is much worse than their opponent. This kind of situation gives rise to a very different conversation.
If your friend Sarah was endorsing something along these lines – say that her favorite team will win the championship this year – perhaps you might point out to her that most experts think her team won’t even make the playoff. Notice the difference – you aren’t actually saying that they won’t win. Strange things happen sometimes. What you have done here is to point out that Sarah doesn’t have any good reasons for believing what she does about her team. Instead of undermining the T in JTB, this kind of defeater attempts to undermine the J in TJB. These are called rebuttals or rebutting defeaters in philosophy. Whereas a refutation tells someone they are incorrect, a rebuttal is more like telling someone that they are being unreasonable/irrational/biased.
Why Does All of This Matter?
These distinctions might be philosophically interesting, but does it really matter? Why would thinking about the differences between rebuttal and refutation impact anything in day to day life?
The difference actually matters a good deal. In fairly insignificant situations – like that of the upcoming baseball game – it doesn’t matter too much. But if the disagreement is over something much more consequential – say matters of politics, religion, ethics, or health – avoiding erroneous thinking becomes all the more important. In these areas, accepting something false or rejecting something true can cause harm.
The actual impact of rebuttals and refutations are different. To see why, suppose I am a Democrat for reasons A, B, and C. Then, imagine I get into a conversation with a conservative friend, who makes some really good rebuttals, and in the end convinces me that A actually isn’t a very sensible thing to believe. Does this now mean that I should cease to be a Democrat? Well, not necessarily. It might be that B and C are strong enough reasons to remain justified in your overall political stance and you only need to make some small changes. Or perhaps B and C are fairly weak reasons and A was your central reason, in which case some kind of bigger picture change in your beliefs would be justified and perhaps even necessary. But even in that case, these rebuttals don’t force you to become a conservative.
Now, imagine a different situation. Maybe you are an atheist (i.e. you believe that God does not exist). Maybe you have some reasons X, Y, and Z why you think there is no God. Imagine then that your friend, who thinks there is a God, gives you his reasons A, B, and C for thinking that God does exist. This ought to give you pause, since this is a refutation, not a rebuttal. Your friend is not claiming that your reasons are bad, he is claiming he has even better reasons that prove you wrong. In this case, what matters is the relative strengths of the reasons. You ought to base how you go forward based on the relative strength of your reasons versus his. And if you find his reasons better than yours, then you have an obligation to admit you were wrong and to change your mind.
The point is that since rebuttals and refutations take their aim at different parts of human thinking, we should process them accordingly. Rebuttals can be perfectly valid but not touch the truth or falsehood of the belief in question, whereas refutations always deal with truth or falsehood. But this distinction does not mean rebuttals can be ignored – it depends on what they target. If someone gives you a rebuttal against your belief that your brain functions properly, you better take that seriously! The nature of these questions is complicated and depends on context. This is why, when we engage in conversation with others, we should be careful to understand which situation we are in, what the consequences of people’s rebuttals/refutations actually are, and to hold ourselves to a high intellectual standard – being neither too hasty nor too hesitant in admitting when we are wrong.