There are some mental categories we draw that are relatively simple and straightforward. Others get trickier, because they are primarily drawn in such a way that whether or not something fits into that category is important information to our utility function. Deciding whether someone is "alive", for instance. Is someone like Terry Schaivo alive? This issue is why, in part, technology creates new moral dilemmas, and why teaching morality to a computer is so hard.
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This post is part of the Rerunning the Sequences series, where we'll be going through Eliezer Yudkowsky's old posts in order so that people who are interested can (re-)read and discuss them. The previous post was Mirrors and Paintings, and you can use the sequence_reruns tag or rss feed to follow the rest of the series.
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