Slaves of the Passions. By Mark Schroeder. (Oxford UP, 2007. Pp. 224. Price US$85.00.)

Ron likes to dance. Brad does not. So the fact that there will be dancing at the party is a reason for Ron to go but not for Brad. The difference in Ron and Brad's desires explains the difference in their reasons. Ron has the reason he does because he has a desire whose satisfaction would be promoted by acting on the reason. The Humean Theory of Reason takes these natural and plausible thoughts and generalises them. Desires explain reasons. A reason for A to φ is some truth that contributes to the explanation of how φ‐ing would contribute to some desire of A's. All that needs to be the case for you to have a reason to do something is that you have some desire that would be promoted by doing it. You have a reason, then, to do anything that speaks to any of your desires. This seems to have the unpalatable consequence that we all have a huge number of reasons to do all manner of very silly things. But this consequence, thinks Schroeder, can be made palatable. We have indeed a vast number of reasons to a vast number of things. Given that, bare existential claims about reasons fail to be very informative. (I have a reason to go to Sumatra. How so? Well because I like chocolate and they have chocolate there and because I like being able to breathe and they have air there and so on and so on. And similar considerations will tell you I have reason to go to Melbourne and Timbuctu and Auchtermuchty and really just anywhere.) Given which, Schroeder proposes, Grice's Maxim of Quantity (the injunction to be as informative as is required) tells us such claims normally carry the implicature that the reason in question is relatively weighty, weighty enough to have a significant bearing on what to do. That's what explains the intuition that we have no reason to do many things we do have reasons to do. It is because so many of these reasons are of very low weight, with the consequence that claims that they exist, while true, are not assertible.