The four papers (Biener, Dupre, Kosman, and Psillos) published in this issue are a subset of those originally presented at the fourth meeting of the biennial Athens-Pittsburgh Symposium in the History and Philosophy of Science and Technology, a joint undertaking of the University of Athens, the National Technical University of Athens, the University of Pittsburgh Center for Philosophy of Science, and European Cultural Center of Delphi. The topic of the symposium, convened at the European Cultural Center of Delphi, was Forms of Proof and Demonstration in Philosophy and Science. These symposia are held every two years in Greece in recognition of Athens as the birthplace of Western philosophy (all of them supported by the University of Athens, the National Technical University of Athens, and the University of Pittsburgh Center for Philosophy of Science). The arst Athens-Pittsburgh Symposium, devoted to the Problem of Anthropomorphism in Science and Philosophy, also took place at the European Cultural Center of Delphi in 1996. The second focused on Greek Medical Traditions from Hippocrates to Harvey, and was held at the University of Athens in 1998. The third, a conference on Experience and Knowledge, met at Rethymnon on the island of Crete in 2000. For the arst three of these symposia, the Latsis Foundation has provided major funding, supplemented by funding from the Harvey and Leslie Wagner Endowment. The European Cultural Center of Delphi was major contributor to the fourth Symposium. The Athens-Pittsburgh Planning Committee consisted of Dionysios Anapolitanos (Athens), Michael Frede (Oxford), John Cooper (Princeton), James Lennox (Pittsburgh), Gerald Massey (Pittsburgh), John McDowell (Pittbsurgh), plus the two symposia co-chairs Baltas and Machamer.