Peter Baumann

The well known Monty Hall-problem has a clear solution if one deals with a long enough series of individual games. However, the situation is different if one switches to probabilities in a single case. This paper presents an argument for Monty Hall situations with two players (not just one, as is usual). It leads to a quite general conclusion: One cannot apply probabilistic considerations (for or against any of the strategies) to isolated single cases. If one does that, one cannot but violate a very plausible non-arbitrariness condition and is led into a Moore-paradoxical incoherence. Even though arguments for switching are correct as applied to series of games, they don’t say anything useful about what rationality demands in a single case.

1. Here is a very simple game. You come up with a number and I come up with a number. If I come up with the higher number, I win; otherwise you win. You go first. Call this ‘The Very Simple Game’. Few would play it if they had to go first and many if they are guaranteed to go second.2. Here is another one. You come up with a number n and I come up with a number m. If m times 1/ n > 1, then I win; if not, then you win. You go first. Call this ‘Still The Very Simple Game’. Since I win just in case m is greater than n, this game collapses into The Very Simple Game. Few people will play it if they have to go first.3. Here is a third one. Let us call it ‘Looks Like A Tricky Game’. Suppose you have a choice between exactly two actions: keep holding on to some thing t ; hand t over to me and accept my offer to give you, with some probability p, some thing with utility m.Suppose, you are a maximizer of expected utility with …

Philip Kitcher recently argued for a reconstruction in philosophy. According to him, the contemporary mainstream of philosophy has deteriorated into something that is of relevance only to a few specialists who communicate with each other in a language nobody else understands. Kitcher proposes to reconstruct philosophy along two axes: a knowledge axis and a value axis. The present article discusses Kitcher's diagnosis as well as his proposal of a therapy. It argues that there are problems with both, and it ends with an alternative view of what some core problems of the profession currently are.

This paper argues against common views that at least in many cases Robert Nozick is not forced to deny common closure principles. More importantly, Nozick does not – despite first (and second) appearances and despite his own words – deny closure. On the contrary, he is defending a more sophisticated and complex principle of closure. This principle does remarkably well though it is not without problems. It is surprising how rarely Nozick’s principle of closure has been discussed. He should be seen not so much as a denier of closure than as someone who’s proposing an alternative, more complex principle of closure.