Acknowledgement
We wish to thank all the participants in the workshop for making it such a fruitful event, and particularly Ariel Rubinstein, who contributed the most to organise it. The authors cooperated in a way that deserves praise. We should acknowledge the always supporting contribution of the Urrutia Elejalde Foundation, as well as the economic support from the Spanish Ministry of Education (grants HUM2005‐01686/FISO and HUM2005‐25447‐E), and from the Department of Logic, History, and Philosophy of Science of UNED.