<寄稿論文>IPCC報告書における主観的確率の使用と半透明ボックス化

Abstract

In the IPCC assessment reports on climate change, the authors use language of confidence and likelihood in the main conclusions such as whether global warming is progressing or whether the warming is caused by human influences. The usage of such language has been scrutinized in detail and every assessment report adds some sophistication in the language. As to likelihood, qualitative expressions like ‘virtually certain’ are accompanied by numeral interpretations like ‘99-100 percent’. This case is very interesting in that scientists themselves seem to express subjective probability consciously. One of the reasons why such language is called for is that the IPCC assessment reports are intended for non-experts, rather than experts inside of the research community. In this paper, I examine the relationship between confidence and likelihood in IPCC assessment reports and what Bayesian philosophers has called subjective probability. Then, I propose the notion of ‘translucent-boxing’ as a role of such subjective probability language in science communication. At the end of the paper, I also make proposal for a better language of confidence and likelihood in IPCC assessment reports from this point of view.