The Circularity of the Design Inference
|November 14, 2014||Posted by Winston Ewert under Intelligent Design|
Keith S is right. Sort of.
As highlighted in a recent post by vjtorley, Keith S has argued that Dembski’s Design Inference is a circular argument. As Keith describes the argument:
In other words, we conclude that something didn’t evolve only if we already know that it didn’t evolve. CSI is just window dressing for this rather uninteresting fact.
In its most basic form, a specified complexity argument takes a form something like:
- Premise 1) The evolution of the bacterial flagellum is astronomically improbable.
- Premise 2) The bacterial flagellum is highly specified.
- Conclusion) The bacterial flagellum did not evolve.
Keith’s point is that in order to show that the bacterial flagellum did not evolve, we have to first show that the evolution of the bacterial flagellum is astronomically improbable, which is almost the same thing. Specified complexity moves the argument from arguing that evolution is improbable to arguing that evolution didn’t happen. The difficult part is showing that evolution is improbable. Once we’ve established that evolution is vastly improbable, it seems a very minor obvious point that it would therefore not have occurred.
In some cases, people have understood Dembski’s argument incorrectly, propounding or attack some variation on:
- The evolution of the bacterial flagellum is highly improbable.
- Therefore the bacterial flagellum exhibits high CSI
- Therefore the evolution of the bacterial flagellum is highly improbable
- Therefore the bacterial flagellum did not evolve.
This is indeed a very silly argument and people need to stop arguing about it. CSI and Specified complexity do not help in any way to establish that the evolution of the bacterial flagellum is improbable. Rather, the only way to establish that the bacterial flagellum exhibits CSI is to first show that it was improbable. Any attempt to use CSI to establish the improbability of evolution is deeply fallacious.
If specified complexity doesn’t help establish the improbability of evolution what good is it? What’s the point of the specified complexity argument? Consider the following argument:
- Each snowflake pattern is astronomically improbable.
- Therefore it doesn’t snow.
Obviously, it does snow, and the argument must be fallacious. The fact that an event or object is improbable is insufficient to establish that it formed by natural means. That’s why Dembski developed the notion of specified complexity, arguing that in order to reject chance events they must both be complex and specified. Hence, its not the same thing to say that the evolution of the bacterial flagellum is improbable and that it didn’t happen. If the bacterial flagellum were not specified, it would be perfectly possible to evolve it even thought it is vastly improbable.
The notion of specified complexity exists for one purpose: to give force to probability arguments. If we look at Behe’s irreducible complexity, Axe’s work on proteins, or practically any work by any intelligent design proponent, the work seeks to demonstrate that the Darwinian account of evolution is vastly improbable. Dembski’s work on specified complexity and design inference works to show why that improbability gives us reason to reject Darwinian evolution and accept design.
So Keith is right, arguing for the improbability of evolution on the basis of specified complexity is circular. However, specified complexity, as developed by Dembski, isn’t designed for the purpose of demonstrating the improbability of evolution. When used for its proper role, specified complexity is a valid, though limited argument.