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 that I should most read. I believe the summary of the back of the book sums it up excellently so share it wholesale:

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.