Suppose that Tom and Sally have a disagreement over a factual question (as opposed to one of values or preferences). She claims that the argument he is making has errors or is unconvincing, but Tom feels the same way about her argument. They debate the question for an hour, but afterwords are still each adamantly convinced that his or her own reasoning is sound while the other person’s is flawed. In this instance, is each person really more justified believing in his or her own belief than he or she is in believing the other person’s belief? More specifically, from Tom’s perspective is it really more likely that his own beliefs are more likely to be correct than hers? What about from Sally’s perspective?
Notice that in the situation described above the only information given so far that differentiates Tom’s argument from Sally’s is that Tom’s mind labeled his own argument true whereas Sally’s mind labeled hers as true. Both of them are aware of this. In order for this difference to be a good reason for Tom to believe his own belief rather than Sally’s, he must be able to explain why things that are labeled true by his mind are more reliable than things that are labeled so by hers.
If it were the case that Tom’s mind was more reliable at correctly identifying truth than Sally’s (in the particular topic area of their discussion), then he might be able to justify believing his own belief rather than hers on these grounds. But if that were the case, and he and Sally both knew it, then she would also have the same reason to believe his belief rather than her own. On the other hand, if her mind were more reliable at discovering truth than his, that would be a justification for her believing her own belief rather than his, but it would also give him the same reason to believe her idea and not his own. In other words, if it is mutually understood that one of the two is a more reliable truth identifier than the other, then they both have that as a reason to trust the ideas of whoever is better.
But what happens if Tom and Sally disagree about who is better at determining the truth on this subject? That is, what if she thinks her truth identification is superior and Tom thinks his is? Now the question of who is right has been raised one level higher than before. Why should Tom believe that he is better than she is at determining who is a better truth identifier? How can Tom justify using his own view of his truth-finding abilities rather than hers? Unless they both agree that Tom is better at identifying who is a better truth identifier, the problem is raised yet another level higher! Occasionally, one can settle this question fairly objectively, by asking how often each person has proven to be correct on past predictions related to this subject. But in the general case, there may be no resolution.
So far, all of the information that has been presented has been symmetric in that if it causes Tom to believe something, it should cause Sally to as well and vice versa, so long as it is known to them both. But one thing that differentiates Tom’s argument from Tom’s perspective and Sally’s argument from Tom’s perspective is that Tom at least knows that he is not purposefully deceiving himself. From his perspective though, he can’t be sure that Sally really believes what she claims to, and can’t rule out the possibility that she is fabricating evidence. So in situations where Sally’s is likely to be deceitful, Tom may be justified favoring his argument on those grounds (keeping in mind that people do deceive themselves all the time, though at least they rarely do so on purpose).
Perhaps the best reason Tom can have to favor his argument over Sally’s, however, is if he can confirm that she is using reasoning processes that don’t reliably lead to truth, but neither she nor he is able to make the same claims about his arguments. For instance, while applying the rule “If A implies B then not B implies not A” will lead to valid conclusions, applying the rule “if A implies B then not A implies not B” will generally not lead to valid conclusions. So her argument is problematic if it relies on a point like “if something violates a human right, it is generally considered to be wrong, but this does not violate a human right, so it isn’t generally considered wrong.” Pure logical fallacies are not the only non-truth generating type of argument though. Some other types of arguments which can (at least in many cases) be non-truth producing are those that rely on:
- sketchily defined words (e.g. “A fetus is not yet a human.”)
- emotional reasoning (e.g. “I feel that he has wronged me, therefore he has”)
- intuition (e.g. “It’s obviously true from my experiences that I make decisions, therefore I have free will”)
- metaphors (e.g. “Taxing a person is like robbing them, and we all agree robbery is immoral so we must agree that taxes are too.”)
- facts that themselves are left undemonstrated (e.g. “Although you have nothing in common, you should go on a date because opposites attract.”)
So if you find yourself in a factual debate and it continues to go unresolved, ask yourself:
- “by objective 3rd party measures (like prediction accuracy), am I a more reliable truth identifier in this situation than she is?”
- “How likely is it that she is deceiving me about what she really believes or knows?”
- “Does her argument rely on procedures that don’t reliably produce the truth? Does mine?”
You need good reasons to believe your own beliefs. You are not justified in believing your own thoughts over other people’s merely because they are your own!