The charge is often made that ID constitutes an argument from ignorance (a charge I’ve shown to be false here). But a case can be made that conventional evolutionary theory, insofar as it tries to explain macroevolutionary changes, itself constitutes an argument from ignorance. In Gary Jason’s book Critical Thinking (p. 133), he characterizes the argument from ignorance as follows:
[The argument from ignorance is] the fallacy of arguing that something must be true because nobody can prove it false or, alternatively, that something must be false because nobody can prove it true. Such arguments involve the illogical notion that one can view the lack of evidence about a proposition as being positive evidence for it or against it. But lack of evidence is lack of evidence, and supports no conclusion. An example of an appeal to ignorance: Styrofoam cups must be safe; after all, no studies have implicated them in cancer. The argument is fallacious because it is possible that no studies have been done on those cups or that what studies have been done have not focused on cancer ( as opposed to other diseases).
In this light, consider how evolutionists attempt to explain the evolution of the bacterial flagellum. Do they provide a detailed, testable Darwinian pathway to the bacterial flagellum? No. The best they do is point to a microsyringe embedded within the flagellum (known as the type three secretory system, or TTSS). But this will hardly do since virtually all engineered systems contain subsystems that are functional in their own right. The challenge is to provide a gradually complexifying sequence of functional intermediates that goes from near zero complexity through the TTSS all the way to the bacterial flagellum. Evolutionists have nothing like this. In other words, they have no positive evidence for the adequacy of the Darwinian or other material evolutionary mechanisms to produce the bacterial flagellum (a point admitted by James Shapiro and Franklin Harold — see here). Moreover, they rule out of court all evidence for design of the flagellum because such evidence fails to exclude all logically possible Darwinian pathways to the flagellum. In other words, because ID proponents haven’t proven that the evolution of the bacterial flagellum could not possibly have happened by purely material means, therefore it happened by purely material means. That fits the bill as an argument from ignorance.