The Simulation Theories of Dreaming: How to Make Theoretical Progress in Dream Science

Among the most pressing challenges for dream science is the difficulty of establishing theoretical unification between the various theories, ideas, and findings that have been presented in the literature to answer the question of how it is possible to construct a solid scientific theory with predictive and explanatory power in dream science. We suggest that the concept of “world-simulation” serves as the core concept for a theoretically unified paradigm to describe and explain dreaming. From this general concept, more specific theories of the function of dreaming can be derived, such as the Threat Simulation Theory (TST) and the Social Simulation Theory (SST) , as we argued in our target article. We agree with Dresler that these two functions may not be the only functions of dreaming, but we still have grounds to believe that they are the strongest contenders. In our reply we first clarify why the functions of sleep should be considered separately from the functions of dreaming. Second, we outline what a good scientific theory of dreaming should be like and what it should be capable of. Furthermore, we evaluate the current state of simulation theories within this context. To conclude, we propose that instead of a general multifunctional theory of sleep and dreaming, where no hypothesis is excluded, the future progress of dream science will benefit more from opposing, competing and mutually exclusive theories about the specific functions of dreaming. This, however, demands that the opposing theories and their predictions must be risky, clearly formulated, and empirically testable.