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Caledonian2 comments on Where to Draw the Boundary? - Less Wrong

36 Post author: Eliezer_Yudkowsky 21 February 2008 07:14PM

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Comment author: Caledonian2 23 February 2008 03:50:20PM 0 points [-]

What actually matters is that including dolphins in that category leads to making incorrect inferential predictions [...] as well as weakening the ability to make correct ones.

First off, making any inferential predictions based solely on the fact that two things are in the same category is unwise. Inferences are strong when they are founded in a wide and deep knowledge base. They are always weak when founded on a single point, regardless of what that point is. If we know nothing about the sorts of things that are included in 'aquatic animals' or the criteria that defines the category, having only two examples doesn't permit us to conclude much of anything about how similar those things are.

Secondly, if we try to make category-based inferences anyway, any categorical distinction lends itself to the errors you've mentioned. Even two dolphins have many things that are different between them. That is not a reason to refuse to have the category 'dolphin' or to place things in it.

What kinds of properties is your "aquatic animals" category better at predicting?

Categories and labels are not supposed to be used to predict anything. That is not their purpose or function, and not surprisingly, they are not well-suited for the task. They are used to indicate that a specific set of similarities hold: this set can include many different properties, or only a single one. They say absolutely nothing about additional properties. They're descriptions, and descriptions only.

When words permit us to make additional predictions about properties that we care about, we find those categorical distinctions more useful than others. But useful is not the same as correct, and any correct distinction has an inherent usefulness.