The scientific standards of the Environmental Protection Agency (EPA) include the use of retrospective meta-analysis. This analysis entails a use of the theory of probability that is only a simulation and cannot accurately measure the confidence that should be placed in the results. The uncertainty necessary for probability is, in a retrospective study, simulated rather than real. There are three logical forms for establishing a proposition. In the logic of the syllogism, a proposition is established by deduction from assumed propositions. In the logic of the physical sciences, a proposition is established by its ability to predict the outcomes of future experiments. In the logic of the courtroom, a proposition is established by its ability to explain past events. The logic of the courtroom operates under the handicap of working with nonrepeatable events. It is more subject to the preferences of the judge than the logic of the physical sciences or that of the syllogism. Because the logic of the courtroom is less reliable than either the logic of the physical sciences or that of the syllogism, it is the logic of last resort, i.e., it is used only when the other two are not applicable. Under the EPA scientific standards, the logic of the courtroom is accepted for establishing propositions about the physical world. As the logic of the courtroom is less reliable than that of the physical sciences, this practice increases the likelihood of errors.