"Qualia" provides one of the most difficult questions for the philosophy of mind, since it seems impossible to explain how a phenomenal-sensible quality like color is produced from colorless electronic-chemical processes in a brain. The purpose of this paper is to propose a causal theory of qualia affirming that a qualia is causally produced by some brain state, and thereby "naturalize" qualia in a certain sense. In order to do that, we must, on one hand, eliminate any anthropomorphic implication from the concept of causality, and, on the other hand, abandon the classical concept of matter and substance to fill the conceptual gap between the mental and the physical. We first examine the concept of causality. We distinguish the ordinary concept of causality (1) and the logical concept of causality expressed by counter-factual conditional (2). We use the concept of causality only in a meaning (2), when we explain the relation between brain and qualia causally. We next interpret the philosophy of science of Gaston Bachelard in order to adopt his theory to the problem of qualia. He criticized the classical concept of matter or substance, and affirmed that far from being reducible to a single level, reality involves a hierarchy where lower level structures produce a quality in a higher level. We show that the same can be said about the relation between brain and qualia. Finally, we conclude that we can maintain a causal theory only if we use the logical concept of causality and reject the classical presupposition of substance.