The goal of evolutionary theory is to (a) specify the general causal structure of evolving systems and (b) analyze evolutionary consequences that are expected to result from the proposed structure of the model systems. Biologists frequently emphasize the hypothetico-deductive method in evolutionary theory. I will show that this method primarily provides a tactical device for (b), while evolutionary synthesis requires a foundation of a unifying conceptual model for (a). Therefore, any successful strategy for a new synthesis requires both a new conceptual insight of evolving systems, and tactical devices for analyzing new specific aspects of the evolutionary process.