How to Detect an Android

A number of prominent researchers in Artificial Intelligence look forward to a time when androids will co-exist with humans. In such a world the question 'Can Machines Think?' will be answered in the affirmative, if it is asked at all. A far more pressing problem will be whether androids could be differentiated from humans in some way. It is argued that an undetectable android cannot be manufactured and a method is presented for distinguishing between androids and humans.