Inductive Reasoning

I think a lot of people naturally use inductive arguments in their efforts to prove facts without really understanding the nature of induction.

Inductive reasoning uses examples of individual instances to try to come up with a generality.

All swans we have ever seen are white.

Therefore swans are white.

Or

Everyone we know of who drinks cyanide dies.

Therefore cyanide is lethal to everyone.

Again, we are using specific examples of an event to try to come up with some general rule.  And this is very good for navigating through the universe and figuring things out, but isn’t good at formally proving anything.  “Swans are white” is great until you actually discover a black swan, or meet someone who has some sort of mutation that renders cyanide harmless to them.

Inductive reasoning is a good first step to figure out what is PROBABLY true, but not good at proving it to be ABSOLUTELY true.  We’ve never seen Bigfoot, but we can’t prove he DOESN’T exist using inductive reasoning.  He could be just behind the next bunch of trees, or he could have circled around behind us to hide somewhere we’ve already looked.

Contrast this with deductive reasoning.  This is the opposite, where you move from a generality to prove a specific.

All zebras are black and white striped.

A baby zebra is about to be born at the zoo.

Therefore, it will be black and white.

The strength of a deductive argument rests on the first line (the generality).  IF that is true, then the following lines should also be absolutely true.  In my example above, I think we should question the first line for its veracity.  Here’s another example:

All even numbers can be evenly divided by 2.

342 is an even number.

Therefore, it can be divided by true.

If A and B are true, then we know for a FACT that C is as well.

They are kind of subtle and hard to wrap your head around at first, but they really come up a lot in theological arguments.

I’ve seen videos of people (Ray Comfort, etc) who will hold up a piece of paper with a circle on it. The circle, they say, represents all possible knowledge of everything in the universe.  What percent, they ask, of knowledge do we have?  The answer is, of course, very little.  No one knows the number of grains of sand on the beach, the number of hairs on our heads.  So the speaker draws a tiny little circle to represent the subset of human knowledge.  Isn’t it possible, then, then God exists outside somewhere outside that little circle?

The answer they want, of course, is “yes, it’s possible that God exists”.  They use this to claim that there are no real atheists, only agnostics, and it basically gives them a foot in the door which they can expand upon.  “You even admitted yourself that God may exist and that you’re a sinner!”

The obvious problem, though, is that using that exact same logic, they have also proved that ANY imaginary or mythological creature may also exist.  Unicorns, leprechauns, the FSM.  We are forced to conclude that they are possible when we see how much we don’t know.

Also, we could turn the argument on its head.  Out of all that knowledge that we don’t know yet, isn’t it possible that there exists some ultimate, conclusive proof that no gods exist at all?  By the same reasoning, the evangelist should be willing to admit that he isn’t sure if he’s right or not.

Basically, you can use that argument to demonstrate that anything is possible, which makes the whole thing generally worthless.

Atheists use it too, of course.  We have never seen direct, incontrovertible proof of God.  This might lead people to claim that he absolutely doesn’t exist.  I don’t think we can draw that conclusion absolutely, but I think we can being to make some statements on probability.

And that’s what induction is really good for.  Making some decisions on what is PROBABLY true, rather than what is absolutely true.  No one has seen Bigfoot, and a lot of people have looked around pretty hard, therefore it’s probably unlikely that he actually exists, but remains “unproven”.

Keep your ears open for people trying to prove things using inductive reasoning.  And note that just because someone is using an inductive argument doesn’t mean that they’re wrong.  Inductive arguments are very useful for figuring out what is probably true, but it’s a common pitfall to use them to try to prove something as absolute fact.