No matter how rigorously it might have been tested, every theory is “just a theory.”2 Because of the way that scientific evidence is gathered, it is always theoretically possible that some future piece of data might come along and disprove a theory. This does not mean that scientific theories are unjustified or unworthy of belief. But it does mean that at some point scientists must admit that even their strongest explanations cannot be offered as truth, but only strongly warranted belief based on 20 CHAPTER 2 justification given the evidence. This alleged weakness of scientific reasoning is often exploited by those who would claim that they are the real scientists—that if science is an open process, then it should not be in the business of excluding alternative theories. Until a theory is absolutely proven, they believe, a competing theory could always be true.