This book develops the paradigm that any complex entity must have an accurate internal model to inform it of the available resources and opportunities given its nature and environment. Such knowledge is necessary to make the entity's complexity compatible with the second law. The model's accuracy may only be maintained through Bayesian inference; updating the model upon the reception of new data or experience in accordance with Bayes' theorem. I argue further that Darwinian processes are a physical implementation of Bayesian inference. In quantum systems the internal model takes the form of the wave function and the process of Quantum Darwinism is seen as responsible for maintaining the predictive accuracy of the wave function.Such systems may be found throughout nature and include (system -internal model - theory explaining inference):1.Quantum systems - wave function - quantum Darwinism2.Biological systems - genome - natural selection3.Brains - neural connections - Bayesian Brain & Synaptic Darwinism4.Cultures - cultural knowledge, for example science - evolutionary epistemologyThe huge number of scientific theories in subject matter as diverse as quantum theory, cosmology and archeology which employ a Darwinian process to explain the creation and evolution of their subject matter motivates the meta-theory of Universal Darwinism, developed by Dawkins, Dennett, Blackmore and others. This book attempts to further develop this theory and to put it on the foundation of information theory.