Rationality and Intelligence: A Brief Update

Abstract The long-term goal of AI is the creation and understanding of intelligence. This requires a notion of intelligence that is precise enough to allow the cumulative development of robust systems and general results. The concept of rational agency has long been considered a leading candidate to fulfill this role. This paper, which updates a much earlier version (Russell, 1997), reviews the sequence of conceptual shifts leading to a different candidate, bounded optimality, that is closer to our in-formal conception of intelligence and reduces the gap between theory and practice. Some promising recent developments are also described. 1 Artificial Intelligence AI is a field whose ultimate goal has often been somewhat ill-defined and subject to dispute. Some researchers aim to emulate human cognition, others aim at the creation of intelligence without concern for human characteristics, and still others aim to create useful artifacts without concern for abstract notions of intelligence. My own motivation for studying AI is to create and understand intelligence as a general property of systems, rather than as a specific attribute of humans. I believe this to be an appropriate goal for the field as a whole, and it certainly includes the creation of useful artifacts—both as a spin-off from and a driving force for techno-logical development. The difficulty with this “creation of intelligence ” view, how-ever, is that it presupposes that we have some productive notion of what intelligence is. Cognitive scientists can say “Look, my model correctly predicted this experi-mental observation of human cognition, ” and artifact developers can say “Look, my system is worth billions of euros, ” but few of us are happy with papers saying “Look, my system is intelligent.” A definition of intelligence needs to be formal—a property of the system’s input, structure, and output—so that it can support analysis and synthesis. The Turing test does not meet this requirement, because it references an informal (and parochial) human standard. A definition also needs to be general, rather than a list of special