This is an old post that I am bringing up to the present.
Jason in his comment on a previous entry says that Carrier is making a mistake when he claims that our current political dialogue shows that we do a lot of things without making rational inferences. I think Jason is right, and I think I can illustrate his point by explaining one of the great intellectual discoveries that philosophy has ever produced, and that is the Aristotle's distintion between the form and the content of rational arguments.
Consider the following argument:
1. If Saddam Hussein has weapons of mass destruction, the we ought to invade Iraq.
2. Saddam Hussein has weapons of mass destruction.
3.Therefore, we should invade Iraq.
The argument is valid, and even Michael Moore ought to recognize that if the premises are true the conclusion must be true. Anyone who recognizes that the conclusion follows from the premises performs a rational inference. If we couldn't perform inferences like these, we couldn't have political dialogue at all. An argument is valid just in case, if the premises are true, then the conclusion must be true. It has nothing to do with whether or not the premises are true, or whether or not we are rational in believing the premises.
Now we can ask whether the premises were true (in 2003), or whether people were rational in believing them. Maybe the people who not only drew this inference but also accepted the premises and hence the conclusion are guilty of various kinds of irrationality, perhaps suffering from Halliburton bias, or Bush bias. And we can ask how rational people really are in the way in which they make their political choices. I happen to think, with Carrier, there's plenty of irrationality in political belief-formation. Nevertheless they do draw inferences. The argument from reason says that if naturalism is true, we will not find people performing rational inferences at all.