+ And, again, socio-psychological facts like character assessments are precisely those for which we have the _most_ reason to distrust each other's judgement: if I like Mary, I might say favorable but false things about her even if I would never tell a lie about homotopy groups. In the absence of a objectively calibrated compassion-o-meter, psychological scientists who want to study individual differences in compassion are mostly limited to doing statistics on people's verbal self-reports and other-reports—but if you don't trust what people _say_, it's at least not _obvious_ whether or how much more you should trust statistical analyses of what people say, in accordance with the ancient dictum: ["garbage in, garbage out."](https://en.wikipedia.org/wiki/Garbage_in,_garbage_out) Probably the neuroscientists are working on the compassion-o-meter, but they too face the problem of ensuring that their interpretations of their brain scans actually mean what they say they mean.
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