So, if you force a polygraph engineer to submit to a polygraph test and then during the test ask them if the machine can accurately detect lies, would that cause a loop in the fabric of causality and could you then cook a burger with it?
Also, no one is claiming that the polygraph actually determines the truth of what someone is saying, only that it determines if the person believes what they are saying to be the truth; and most polygraph examiners likely believe that the polygraph works.
Homeopaths Acupuncturists Most broad-stroke psychometric testing