This research proposal addresses from a philosophical perspective the greatest unsolved problem of theoretical physics, namely the formulation of a quantum theory of gravity. Quantum mechanics and general relativity are the two main revolutions of 20th century physics. These theories have radically modified our conceptions about time, space, motion, matter and causality. However, the formulation of a quantum theory of gravity capable of harmonizing these new insights in a consistent synthesis remains an open problem. The absence of an experimental guidance, the conceptual nature of some of the obstructions encountered, and the philosophical origin and scope of the problems to which general relativity and quantum mechanics provided a provisional solution explain why philosophy can play an essential role in helping to accomplish this unfinished revolution . The general objective of this research proposal in philosophy of physics is to address the main (interrelated) foundational issues raised by canonical quantum gravity, notably 1) the consequences of canonical quantum gravity for the ontology of space and time, 2) the debate concerning the relational or substantival commitments of canonical quantum gravity, and 3) the so-called problem of time. In order to accomplish this goal, this research proposal relies on two intermediate subprojects. The first one addresses some foundational problems of general relativity which are of direct relevance for its quantization. The second one addresses the philosophy of canonical quantization. Far from tackling these subjects from scratch, this research proposal interlocks my previous work 1) on the philosophy of quantum mechanics, 2) on the philosophy of gauge theories, and 3) on the canonical quantization of gauge theories.