This article shows how the problems of quantity and quality in large-scale public deliberation can be addressed by Logical Argument Mapping (LAM), a method of argument visualization that will be implemented in the interactive web application "AGORA-net: Participate—Deliberate!" The AGORA net will allow users all over the globe to construct arguments and argumentations in graphical form on the web, to add objections, and to engage thus in deliberation. As an example at the boundary between scientific debate and public deliberation, the article analyzes parts of the controversy about the "Stern Review" on The Economics of Climate Change. It focuses especially on ethical assumptions on which Stern's economic models are based and contributes, thus, to the emerging field of "climate ethics."