I was listening to a debate about the irrationality of theism, and the theist, Randall Rauser introduced me to a concept in philosophy that I had not heard of: properly basic beliefs. Rauser defines rationality in the following way:
Positively, a rational belief is any belief that is either properly non-basic or properly basic. A properly non-basic belief is a belief that is held appropriately in light of supporting evidence. A properly basic belief is a belief that is held appropriately but which does not require evidence.
It seems as if, with this definition, properly basic beliefs are equivalent in function to axioms in mathematics. Fair enough. Examples Rauser and others have used for properly basic beliefs include:
- Your friend Joe says he ate cornflakes this morning.
- The testimony of your wife saying that it is raining outside where she is.
- Jesus rose from the dead.
- A banana is in front of me, because I see it.
Now I am no philosopher (or perhaps I am, depending on whom you ask). That being said, I don't find the concept of "properly basic belief" to be at all clarifying, when we have words like axioms. But, for the sake of charity, I will consider the axioms of math to be properly basic for much of this post. I think, however, that even something as basic as "2+2=4" is an empirical relationship. If the rules of the universe were such that sometimes "2+2=5", then we'd have a different math, and thus the rules of math are really tied to the rules of the universe. However, I could imagine someone successfully arguing that the basic laws of math are "properly basic" in the sense that Rauser would want - rationally held without requiring evidence.
But aside from that, I don't think that any of the other cases are properly basic in this way, especially testimony of any kind. Rauser will say thing like, belief in the testimony of your wife is a properly basic belief because you don't need to go check it out further, get documentary evidence and video evidence to verify it, but you can still believe it rationally. I would agree with all of that, but that doesn't make it properly basic. You don't need to get more evidence, but that doesn't imply that you are accepting it without evidence. You have the evidence of your entire experience with your wife, as a trustworthy person. How do you know she's trustworthy? Empirically! You also have the experience, in general, that even typically untrustworthy people don't tend to be untrustworthy about mundane claims. When you assess the probability that it is truly raining, given your wife's testimony, you are really doing that with a lot of other empirical evidence that you have built up over your life. It is easy to see this is the case, because changing the context can completely change whether you are rational to accept the testimony. Let's say that your wife is in Antarctica. Surely it would not be rational to accept her testimony, and more rational to think she is joking, exaggerating, or mistaken. The same testimony, with a different background experience, yields different probability assignments and thus a different strength of belief in the claim. Thus, the testimony alone cannot be a properly basic belief. You can follow this line of argument for the cornflakes example as well.
The reason we do not simply trust the testimony of others on resurrection claims is the same reason we wouldn't trust the claim of rain in Antarctica - especially because rain in Antarctica is more likely than a resurrection. We have established, empirically, when testimony can be trusted (not at 100 percent ever!), and when it can't. We've established certain patterns that occur when testimony is wrong, and those patterns exist in the Biblical claims. We've established historical patterns, the process of information transmission, the influence of political entities, the scientific workings of the universe, etc... All of this comes into play when establishing the probability of the resurrection.
If we take the axioms of mathematics to be "properly basic", then the probability calculus follows from that, which includes the proper procedures for updating states of knowledge given evidence. All other claims must be based on evidence to be rational, and thus cannot be "properly basic", or axiomatic. Want to challenge the axioms of math? Good luck with that! If we agree to take the axioms of math as "properly basic", then all we need to say is:
Axioms [of math] are statements we believe rationally with no evidence. All other things need to be believed only with sufficient evidence, and the strength of the belief should scale with the evidence.
It is simply a consequence of the math, probability theory in this case. You'll note that the entire term "properly basic" has disappeared, and introducing it would only muddy the discussion, making things less clear than a straightforward application of probability theory.
One final thought. I get the feeling, and I doubt I could ever demonstrate this convincingly, that the only reason someone would suggest that God, or the resurrection, are "properly basic" is because there is so little evidence for these claims yet the proponents do not want to admit that they are being irrational, so the only choice is to dispense with evidence for rational belief altogether. It smacks of a desperate move, but perhaps it is just an example of Shermer's "smart people believing weird things", where they are smart about rationalizing things they came to believe for non-smart reasons.
In either case, I believe it is important to stick to well-established mathematical vocabulary when discussing the basis for beliefs, and not introduce vocabulary that is unnecessary and, as a consequence, unclear.