The Development of St ructural Realism through Substantivalism and Relationism Regarding Spacetime in General Relativity

フジタ, ショウ

Fujita, Sho

オオサカ ダイガク ダイガクイン ニンゲン カガク ケンキュウカ シャカイガク ニンゲンガク ジンルイガク ケンキュウシツ

Sociology, Anthropology and Philosophy, Graduate School of Human Sciences, Osaka University

実体説

関係説

構造実在論

一般相対性理論

philosophy of spacetime

substantivalism

relationism

structural realism

General Relativity

There have been ongoing debates on the existence of spacetime for a long time. This paper will offer one way to interpret more recent debates and present the important aspects of the philosophy of spacetime. General Relativity shows spacetime has a curvature and is bent, due to the infl uence of matter. While substantivalists claim that the bent spacetime exists like other matter and fi elds, relationists claim that spacetime should be reduced to such matter or their properties. In 2000, structural spacetime realism was adovocated, and as a new perspective, it reconciled conventional substantivalism and relationism. Structural spacetime realism recognizes spacetime exists as a whole structure made by metric (gravitational) fields and not by manifolds. Physical worlds exemplify this structure and can be described mathematically. However, I think not only this structural spacetime realism but also some substantivalists and relationists can agree that the nature of spacetime consists in metric and the whole structure created by metric is spacetime’s unique identity. Through this paper, making allowance for general covaliance in General Relativity, I will reveal that it is the “relation” which is important, and realists and anti-realists, including structural realists, discuss spacetime in the same way despite differeces in their formulations.