Combining Minds is also the first book-length defence of constitutive panpsychism against all aspects of the 'combination problem'. Constitutive panpsychism is an increasingly prominent theory, holding that consciousness is naturally inherent in matter, with human consciousness built up out of this basic consciousness the same way human bodies are built up out of physical matter. Such a view requires that many very simple conscious minds can compose a single very complex one, and a major objection made against constitutive panpsychism is that they cannot - that minds simply do not combine. This is the combination problem, which Roelofs scrutinizes, dissects, and refutes. It reflects not only contemporary debates but a long philosophical tradition of contrasting the apparently indivisible unity of the mind with the deep and pervasive divisibility of the material world. Combining Minds draws together the threads of this problem and develops a powerful and flexible response to it.