The Ship of Theseus: a misleading paradox? The authenticity of wooden built heritage in Japanese conservation practice

ABSTRACT The conservation process of Japanese wooden buildings has often been likened to the Ship of Theseus, whose planks were gradually replaced until its material was completely renewed. This analogy suggests that the primary aim of Japanese conservation is retaining the original form, giving little consideration to material authenticity. However, an in-depth analysis of Japanese conservation practice reveals that this comparison is misleading. An examination of the ratios of remaining original material and its distribution in the building shows that historically, replacements were carried out in a limited manner, and complete renovation of the material did not take place. Instead, timbers in the ‘core’ part of the structure remain for the most part original, while timbers in the ‘periphery’ can be replaced several times. In addition, a review of guidelines for the conservation of heritage buildings in Japan shows that retaining ‘as much as possible of the old material’ was considered a fundamental principle from the beginning of modern heritage conservation. Finally, a survey of repair sites shows how this principle is rigorously observed in contemporary practice. As a result of this analysis, it becomes clear that conservation of material authenticity is, in fact, a fundamental concept in the Japanese approach.