Bayesian Investor Blog

Ramblings of a somewhat libertarian stock market speculator

Parfit’s Reasons and Persons

Posted by Peter on July 31, 2007
Posted in: Book Reviews. Tagged: ethics, mind uploading.

Book review: Reasons and Persons by Derek Parfit.
This book does a very good job of pointing out inconsistencies in common moral intuitions, and does a very mixed job of analyzing how to resolve them.
The largest section of the book deals with personal identity, using a bit of neuroscience plus scenarios such as a Star Trek transporter to show that nonreductionsist approaches produce conclusions which are strange enough to disturb most people. I suspect this analysis was fairly original when it was written, but I’ve seen most of the ideas elsewhere. His analysis is more compelling than most other versions, but it’s not concise enough for many to read it.
The most valuable part of the book is the last section, weighing conflicts of interest between actual people and people who could potentially exist in the future. His description of the mere addition paradox convinced me that it’s harder than I thought to specify plausible beliefs which don’t lead to the Repugnant Conclusion (i.e. that some very large number of people with lives barely worth living can be a morally better result than some smaller number of very happy people). He ends by concluding he hasn’t found a way resolve the conflicts between the principles he thinks morality ought to satisfy.
It appears that if he had applied the critical analysis that makes up most of the book to the principle of impersonal ethics, he would see signs that his dilemma results from trying to satisfy incompatible intuitions. Human desire for ethical rules that are more impersonal is widespread when the changes are close to Pareto improvements, but human intuition seems to be generally incompatible with impersonal ethical rules that are as far from Pareto improvements as the Repugnant Conclusion appears to be. Thus it appears Parfit could only resolve the dilemma by finding a source of morality that transcends human intuition and logical consistency (he wisely avoids looking for non-human sources of morality, but intuition doesn’t seem quite the right way to find a human source) or by resolving the conflicting intuitions people seem to have about impersonal ethics.
The most disappointing part of the book is the argument that consequentialism is self-defeating. The critical part of his argument involves a scenario where a mother must choose between saving her child and saving two strangers. His conclusion depends on an assumption about the special relationship between parent and child which consequentialists have no obvious obligation to agree with. He isn’t clear enough about what that assumption is for me to figure out why we disagree.
I find it especially annoying that the book’s index only covers names, since it’s a long book whose subjects aren’t simple enough for me to fully remember.

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