Tractatus primus

Walter Burley’s Tractatus primus forms part of a broad philosophical project centred on the analysis of natural change. The better-known De intensione et remissione formarum (printed in 1496 and also known as Tractatus secundus) is also part of this project. Burley’s study of qualitative change is based on a notion of contraries that differs from the commonly accepted Aristotelian version. For Burley, contraries are measured against the distance from a quality at its highest degree. Therefore, no specific change can be assumed when passing from hot to cold, which clearly reduces the ontology of qualities. Taking degrees of intensity into consideration, the different degrees of quality entail formal, but not specific, change. To use an example from the text, cold is not fundamentally different from hot; it is simply hot at the lowest degree. By ascribing a leading role to the different degrees of qualities, Burley’s project makes significant progress in the study of natural change.