What are rational, justifiable reasons to take the actions that define our lives. What is personal identity? Who am I? Who are you? How do we relate?

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Derek Parfitt is a bastion of the Effective Altruism community and I was told that this was the book of his I should most read. The summary on the back of the book sums it up excellently:

Reasons and Persons challenges, with several powerful arguments, some of our deepest beliefs about rationality, morality, and personal identity. The author claims that we have a false view of our own nature; that it is often rational to act against our own best interests; that most of us have moral views that are directly self-defeating; that we often act wrongly, even though there will be no one with any serious ground for a complaint; and that, when we consider future generations, it is very hard to avoid conclusions which most of us will find disturbing. The author concludes that non-religious moral philosophy is a young subject, with a promising but unpredictable future.

The book took a great amount of focus to get through but the philosophical form of reasoning and ideas presented were highly stimulating. Why should you read this book? What are my biggest takeaways from having read it?

In order of significance:

• Personal identity is very flimsy across someone’s life.
• The Repugnant Conclusion is a major challenge to all ethical theories (if you believe it is a problem… more on this later).
• Dispositions are hard to change. They can result in blameless wrongdoing.
• Self interest theory has a number of problems. Primarily how it treats temporal discounting.
• Consequentialism != Utilitarianism
• The best moral theory is some combination of standard morality and Utilitarianism. This can potentially be encompassed inside the Critical Present Aim Theory.

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Personal Identity is all down to psychological connectedness and continuity

Boat of …

Empty questions.

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The Repugnant Conclusion

The CDF of a normal distribution should do it?

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List of thought experiments:

Footnotes

Thanks to Joe Choo-Choy, Paul Forrester]() Davis Brown for reading drafts of this piece. All remaining errors are mine and mine alone.