From time to time there is a great fuss made about whether some object is a work of art or pornographic. Experts are invited to testify, and mostly ridiculed for their trouble. Witnesses with no expertise at all are treated more courteously; often being commended for their assistance in establishing a community standard. This manoeuvre is prejudiced in two ways. First, those without expertise are not invited to testify in statistically significant numbers, and their opinions are mainly selected and filtered through the calculating minds of lawyers. Second, and perhaps more importantly, no conservative judge and jury seriously believes that a change of mind will ever be the appropriate response to evidence that a more radical opinion than their own is the community standard. (Or vice-versa, for more a radically minded judiciary and a more conservative community standard). All these good people are determined to do the right thing, and no evidence that in the domain of nutrition (for example) eating beef is the community standard will persuade a vegetarian to approve of it. 

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