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19 October 2010

Logical Induction

I just finished listening to this week's episode of The Atheist Experience, a weekly, hour-long, call-in show out of Austin that allows dialogue between the atheist hosts and theist callers.

This week's episode (679 in the archive, show notes here) was nominally on the subject of conspiracy theories, however one caller managed to single-handedly derail the show.

The argument went something like this: the cell is an incredibly complex machine and we know that machines are the result of intelligence; therefore, the cell is the result of intelligence. Or, more formally:

  1. Every machine that we have examined is the result of intelligence.
  2. Cells are machines.
  3. ∴ Cells are the result of intelligence.

This is clearly not a deductively valid argument, however at first glance it appears to be fairly straightforward example of logical induction. So that's fine, as far as it goes. If we assume that the proponent of intelligent design is making an inductive argument, I have two main problems with it:

  1. The fellow kept saying that this is what he had deduced. Once wasn't a big deal, but when he said it over and over again I began shouting at my car stereo and swerving all over the road while flailing my arms wildly, much to the alarm of other drivers.
  2. Not only is the argument invalid, the premises are questionable. He never defined what he meant by "machine". This is actually a fairly major problem, as, depending on one's definition, we have some seventy sextillion machines without intelligent creators.*

But the truly glaring problem with the argument is that it actually isn't a good example of induction at all! Let's compare the argument above to actual logical induction:

  1. Every machine that we have examined is the result of intelligence.
  2. ∴ Every machine the result of intelligence.

It seems to me that the first argument is actually an argument by analogy, and not a very good one.

* One such was described by They Might Be Giants as a "miasma of incandescent plasma". The creationist dismissed the "stars as machines" idea out of hand, however, without actually addressing the point, despite the fact that they are fusion reactors responsible for the manufacture and proliferation of heavy elements throughout the cosmos.

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