The following five rules for making a valid argument are universally applicable. I mention them here because they are too often not followed.*
PZ Myers criticized Greta Christina for her recent article proposing 6 unlikely developments that could convince her to believe in God. PZ Myers complained that Ebonmuse and Greta Christina are 'conceding too much' by engaging in 'what if' arguments to demonstrate the application of the first criteria for valid argument from the above list. PZ claims that the latter four criteria (his four criteria were defined somewhat differently, see his article http://freethoughtblogs.com/pharyngula/2015/04/04/it-is-not-close-minded-to-demand-reasonable-kinds-of-evidence/) are prerequisites that theists can’t meet and therefore discussion should end there. I disagree. While it is arguably true that theists always fail to simultaneously meet all four of the other criteria simultaneously, those four criteria are corollaries of the first criteria. The insistence on starting with, and being dependent upon, empirical evidence is not secondary to the other criteria. Providing examples of how to apply the first criteria concedes only the supremacy of empirical evidence and is not rendered irrelevant or useless because theists fail to simultaneously meet all of the other four criteria.
* This list of debate rules was inspired by a recent public disagreement between bloggers Greta Christina and PZ Myers and borrows from what they wrote.