Speaking of “Tom Kelly”:http://www.nd.edu/~tkelly6/projects.html, I just read “his paper”:http://www.nd.edu/~tkelly6/NousSunk.htm on why the Red Sox were justified in continuing to give at-bats to “Tony Clark”:http://www.baseball-reference.com/c/clarkto02.shtml in 2002 as he put up that gaudy .207/.265/.291 batting line.

Well, strictly speaking, Tom doesn’t defend sending Tony Clark out to GIDP every day, just the rationality of _sometimes_ doing what is usually called ‘honouring sunk costs’. (Tom quibbles about whether this is really the best description of this behaviour in a couple of parts of the paper.)

The rough idea is that since the value of an action is partially determined by what happens in the future (just like “the value of an organism”:http://www.nyu.edu/gsas/dept/philo/faculty/harman/papers/Potentiality.pdf) our current actions can be sometimes justified by the redemptive value they confer on past actions. It’s an interesting idea, though I’m not sure how much it should matter in practice. For one thing, I think we need a more comprehensive theory than Tom offers here about which past actions are worth honouring. (I imagine Tom has such a theory but space constraints kept it out of the _Nous_ paper.) It clearly isn’t worth redeeming an off-season waiver claim by running Tony Clark out there every day when it’s really unlikely he’ll hit the ball out of the infield, let alone out of the park. Tom often refers to the kind of actions that are worthy of redemption as ‘sacrifices’, and I wonder if there’s more to be said about what makes those actions redemption worthy.

Tom also notes that honouring sunk costs, or at least being perceived to do so, can have game-theoretic advantages in certain situations. I’m less impressed by this as an argument for the rationality of such actions. (And Tom doesn’t lean on it particularly.) In some games of Chicken, the best thing to do is to unbolt the steering wheel and throw it out the window. The situations where it is best to honour sunk costs remind me of those games of Chicken. When it works, it’s a neat stunt, but it doesn’t take much for circumstances to change and then it becomes a really really _bad_ strategy.