Apparently he doesn't know that himself. Perhaps you should tell him.
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an assumption is being made that the sign is decietful and thus lying. That sign really is in fact a lie
detector, be it not an electronic one, but a lie detector in a primitive form. So you would be wrong about your assumptions.
I am not saying that you are lying, as that would be the same error. I would rather say that you misunderstood a creationist and perhaps accused him of lying about a lie detector, that does in fact detect lies (just not electronically).
You would have to believe that all lie detectors are of an electronic polygraph type, and this would be wrong. Not to mention the several lie detectors that were used before the polygraph.
early electronic type:In 1921 Larson criticized Marston's intermittent blood pressure method because emotional changes were so brief they could be lost. To adjust for this he modified the Erlanger sphymograph to give a continuous blood pressure and pulse curve and used it to study 4,000 criminals
word counting as a lie detection:
James Pennebaker uses the method of Linguistic Inquiry and Word Count (LIWC), published by Lawrence Erlbaum, to conduct an analysis of written content. He claims it has accuracy in predicting lying. Pennebaker cites his method as "significantly more effective than human judges in correctly identifying deceptive or truthful writing samples"; there is a 67% accuracy rate with his method, while trained people have 52% accuracy. His studies have identified that deception carries three primary written markers. The first is fewer first-person pronouns. Those lying "avoid statements of ownership, distance themselves from their stories and avoid taking responsibility for their behavior" while also using more negative emotion words such as "hate, worthless and sad." Second, they use "few exclusionary words such as except, but or nor" when "distinguish[ing] what they did from what they did not do."
above, from wikipedia on lie detection
