Tuesday, September 25, 2018

Extraordinary claims require extraordinary evidence

In the past, I've generally defended the claim that "extraordinary claims require extraordinary evidence" even against my fellow Christian apologists. Of course the claim can be picked apart, but I agree with the general idea of it. The general idea is that the more unusual or unlikely a claim seems at first to be, the better evidence you're going to require before you'll accept it. If somebody told you they got a flat tire on their way to work, you'd probably just take their word for it. But if somebody told you they ran into Nora Jones on their way to work, and they smooched, their word wouldn't be enough. You'd require stronger evidence. I still agree with that general principle. But I don't agree with how the principle is expressed as "extraordinary claims require extraordinary evidence" because it's sloppy, and it's too easy to pick apart.

I think a better maxim is that any claim requires adequate evidence. Although not as pithy, it's more precise. Of course what's adequate will depend on the claim being made and whatever background beliefs you already have.

The reason I say that is because whether a claims seems extraordinary to you or not depends on everything else you believe. For example, let's say Jim tells Bob, "Hey Bob, I bought a bag of ice at the grocery store today." Well, if Jim and Bob are anything like us, neither will consider that an extraordinary claim. But suppose Bob lived in India three thousand years ago, and he's never seen or even heard of ice. He's never even thought about whether or not water can freeze. Then Jim says, "Hey Bob, I bought a bag of ice from an old woman at the market today." Bob says, "What's ice?" Jim replies, "Ice is solid water. When water gets really cold, it becomes a solid." Well, now Jim has made an extraordinary claim because it goes against everything Bob has ever known about water.

Now, there are undoubtably claims that most of us would consider extraordinary, but what does it mean for evidence to be extraordinary? Let's consider another scenario. Jim and Bob are just average guys who both work at Taco Bell. One day Jim says, "Hey Bob, I stopped at 7-11 on my way to work today and ran into Kate Beckinsale. And the craziest thing happened. Kate kissed me!" Well, Bob will probably think that's an extraordinary claim, and he'll naturally want more than Jim's word on it. So let's say Jim recorded a video with his iphone. The video first shows Jim whispering, "I just saw Kate Bekinsale." Then he turns the camera around and walks through until Kate shows up in the screen. It's her alright. As soon as she sees Jim she walks up to him. Jim faces the camera toward himself and Kate Beckinsale, and sure enough, she kisses him. Well, there's nothing in the world extraordinary about an iphone video. Everybody knows iphones are capable of recording videos in a 7-11.

So here we have an example of an extraordinary claim where the evidence is adequate but not really extraordinary. I say all this to say that the maxim that extraordinary claims require extraordinary evidence is too imprecise. I think the gist of it is true, but it's too easy to pick apart to be very useful, and a more useful maxim to go by is "Any claim requires adequate evidence." And what's adequate will depend on what the other person believes. If you already believe water can freeze, you'll require less evidence that Bob has ice than if you do not already believe water can freeze.

The same thing applies to Christianity. A person who believes the supernatural exists will have an easier time being persuaded that Christianity is true than a person who does not already believe the supernatural exists. A person who believes in God will have an easier time believing Jesus rose from the dead than a person who does not believe in God. So whether the arguments for Christianity will seem persuasive to you (i.e. whether the evidence will be adequate) depends on what you already believe about the world.

All of our beliefs are interconnected. Whenever you're presented with evidence for something you didn't previously believe, your ability to accept the truth of what is being shown to you will depend on how easy it is to accomodate that belief into the rest of your beliefs. It's almost never the case that you can change your mind about one thing without having to change your mind about a few other things. That's because beliefs are interrelated. For example, let's say I'm a naturalist, and I don't think anything but the physical world exists. And I don't believe resurrections are possible because that's not how the physical world works. But then somebody shows me evidence that Jesus rose from the dead. Well, it's doubtful that I could accept that Jesus rose from the dead without also having to change my belief about the natural world. So I would not only have to change my belief about whether dead people can come back to life, but I would also have to change my belief about the physical world being all that exists.

The fewer adjustments you have to make, the easier it is to accommodate a new point of view within your noetic structure (i.e. the sum total of all of your beliefs). The more adjustments you have to make, the harder it is to accommodate a new point of view.

It also depends on the strength of your other beliefs. The stronger they are, the less they'll budge, and the weaker they are, the more they'll budge.

So evaluating evidence is not a purely objective thing. There's a subjective element. This is even true in science where people do everything they can to remove the subjectivity from it. To do that, though, scientists have to begin with certain presuppositions--the validity of logic, the reality of the external world, the reliability of sensory perceptions, the assumption that the future will resemble the past, etc. As long as everybody agrees with these presuppositions, science can proceed, but a person who doubts any of these presuppositions isn't going to find scientific evidence for some view as compelling as somebody who does not doubt these presuppositions. So science only gets objectivity by stipulating a set of presuppositions.


Anonymous said...

How do we know that the senses are reliable?

Sam Harper said...

I talked about knowledge by sensory experience i two posts here and here.