We get email: Brains, evidence, and burden of proof again

Fresh from the “Someone Is Wrong on the Internet” files, this message was sent via the contact form on the ACA website.

My understanding about atheism is you claim that because there is (supposedly) no evidence for God existing that this equates to there being evidence for God NOT existing (please correct me if I am wrong about this).

Kind of, but not exactly.

The default position for any positive claim lacking evidence is usually disbelief.  “Disbelief” doesn’t mean “proof against,” and it doesn’t mean “dogmatic certainty” — it just means, to put it simply, that you generally don’t believe in stuff without having reasons in favor of it.

To give you a small example: Suppose I told you “You know, I died last week, but I rose from the dead on the following morning, so here I am replying to your email.”  Would you believe me or not?

I think it’s safe to say that you would ask me whether I have evidence or not.  My failure to provide any wouldn’t constitute proof that it didn’t happen, but it wouldn’t look good for me.  Don’t you agree?

Or suppose I tried to sell you a car which, by all appearances, seemed to be a twenty year old lemon, but I said “This car has a secret switch which can make it FLY.  And I’m selling it to you for the incredibly reasonable price of $10,000.”  That’s actually a great price for a flying car… but I’m sure you wouldn’t buy it without evidence.

You see the difference between this position and what you’re saying?

My question to you is this:

1) Do you have a brain? You probably think so.
2) How do you know? For the sake of epistomological argument, you could be merely a computer-based machine, akin to a very advanced robot operating on Artificial Intelligence
3) How can you prove this? Given my previous challenge, you probably can’t prove the existence of your brain without cutting open your skull to demonstrate the presence of white and grey matter)

Yes, I’ve heard this one before, there’s a popular urban legend chain mail about a student who stumps a professor with it.  I have a hard time believing that anyone takes that story seriously.

This line of questioning stems from a total confusion about the difference between “evidence” and proof.  You of course couldn’t prove with 100% certainty that any particular person has their own brain; after all, they COULD be a very clever robot.  However, the evidence that we do have is sufficient to that it’s way more likely that you have a brain than any of the alternatives.  For example:

  • Induction (an important tool of science): Every human skull we’ve ever cut open has contained a brain.  Thus the DEFAULT assumption for any given person is that they match an already observed pattern.
  • Necessity: we have built up a pretty good idea of how brains work, and that they are a the source of cognitive processes in people.  In order to say “Person X lacks a brain” you’d have to come up with a credible alternate explanation of why they’re continuing to move around, speak, and write.  Instead of, you know, lying there.  (By contrast, we don’t have any evidence of any particular processes caused by any gods, which means that’s the possibility that requires explanation.)
  • Ruling out alternatives: It’s easy to SAY that your brain’s been replaced with a computer, but as far as we know this can’t be done successfully with any modern techology.  If those kinds of transplants were commonplace, then there would be evidence for the brain switching theory, but there’s not, so following the known pattern is the simplest conclusion.

4) Do you claim to know everything, as in all possible facts? If not, then what percentage of information about the world do you claim to know? 5, 10, 15, 20, 30 %? Whatever the percentage of information about the world which you have knowledge about, it surely is not a full 100% – if this is correct, then the percentage for which you do not have knowledge could, quite possibly, include existence of supernatural phenomena such as the existence of God.

Sure, the possibility is always there, even if the odds are 10^-googol.  You don’t need to convince me that a god is possible.  I just don’t believe that it’s true, due to lack of evidence.  If you want to change my mind about the likelihood, then find some evidence.

My argument then is as follows:
1) You do not really have logical or rational proof for claiming, with certainty, that God does not exist

And, as I just said, I don’t make that claim of certainty.

2) Therefore, you are, by definition, an agnostic, in other words: you are uncertain and do not know the final truth of the matter with regards to God’s existence.

You’re right.  As I’ve said many times on the show, I’m an agnostic atheist.  “Agnostic” because I don’t know whether a god exists, but “atheist” because, given the information currently available, I don’t share your belief that the god exists.

3) You have therefore been mistaken about calling yourself an atheist, since you actually are an agnostic and are simply in need of getting your terms right before using terms such as “atheist” inaccurately

Wrong.  My usage of the word atheist is consistent with the standard definition (as I am not a theist), and also consistent with the viewpoints of many well-established atheists, such as George Smith and Richard Dawkins

Perhaps a more accurate way of describing yourself, as well as your friends and colleagues on your show, could include:
- agnostic

Yes.

- secular

Yes.

- lay

Why, because I’m not a scientist myself?  Okay, I’m a layperson, but I don’t see what that has to do with atheism.  You and I are both lay irrespective of our religious beliefs.

- irreligious

Yes.

- epistemologists

…Sure, if you want.

Now I’ve agreed to your entire list of alternate descriptions, and I’m also an atheist.  If you want to throw some more labels on there, I’m also a computer programmer, a gamer, a father, etc.  None of those things are mutually exclusive with atheism.

Atheism, however, with its claim to conclusively “know” that God does not exist, seems about as irrational as the very belief in God which it seems to have contempt for.

Atheism doesn’t require such a claim of knowledge.  I’m afraid you have been misinformed.  Withholding beliefs in the absence of evidence isn’t irrational, as is obviously the case in my example of the flying car.

Hope that clears things up.