Once there was a king who decided to enact a law whereby every arriving foreigner had to state the true reason for his entry into the kingdom; those who did not tell the truth were to be hanged. This prompted a philosopher, who had only arrived a day earlier, to state that his reason for coming was to get hanged on the strength of the law!
An obvious paradox that through its very logic created an impasse. What must the king have done to escape the awkward position in which the philosopher had placed him? When a paradox appears to create an unsolvable situation, the impasse can often be resolved by considering that such a situation is logically impossible and therefore, of little practical importance.
In short, finding better reasons to hang people; and more precise methods for determining truth from lies, would have been in the king’s best interests. But how do you tell when someone is lying? Detecting a lie isn’t easy…even for experienced professionals in law-enforcement. Recall, that what makes an untrue statement a lie is the intent of the communicator. That is, a deliberate attempt to mislead someone or otherwise conceal information. A lie is only meaningful interms of the response it elicits, as is the case with any communication.
If you respond to one who consistently lies no differently than when he is truthful, the lies serve no purpose– no advantage to either the person lying or the recipient. In contrast, when a lie gains the favor of another (in a manner that a truthful statement would have not), it is reinforced and likely will recur.
Sometimes it is the recipient of the lie that strengthens lying. People may deliberately overlook an obvious lie because they want to believe what is being said. For example, if someone, who is frustrated after several failed attempts at dieting, encounters another who simply says, “I think you look fine, your diet must be working”, in desperation, the dieter might be inclined to believe what he or she “knows” to be a lie. Nobody likes to be fooled. Thus, a recipient of a lie may inadvertently strengthen lying by straining to accept that lie, in order to avoid admitting he or she has been fooled.
At times like these, it becomes compelling to be able to determine with reasonable certainty whether or not someone is being truthful or lying. Some research psychologists have systematized date from inordinate hours of videotaped and personal interviews, in order to determine the verbal, physical and emotional signs that commonly relate to a lie. One such individual, Dr. Paul Ekman of the University of California, has devised a series of clues that frequently reveal lying. An interpretation of these is offered below.

• 1- Check the pitch. Is someone throwing a curve? One who knowingly lies and fears being caught may be tense. As a result, his (her) voice might be strained or higher-pitched than normal. And within this changed pitch, the words might be evasive, repetitive or halting.
• 2- When the shoe doesn’t fit… People who relate truthfully are often “congruent” in their delivery of the message. That is, their verbal message, voice, body posture, and facial expressions seem to match. An example of such congruence might be a husband returning from a tennis match whereupon his wife asks how he did. Looking her in the eye he says, “I played great– he couldn’t touch my serve the entire match.” If accompanied by a relaxed posture, a “serving” gesture, smile and an even but enthusiastic tone of voice, this congruent message might be accepted as true. However, what if his statement rose in pitch as it progressed to a sort of squeal, fidgeting with his damp tennis shirt as he spoke, while looking down at the floor? Clearly, stating he was a winner would not have matched the other indicators. This incongruence could indicate he was lying.

Caution: Skilled liars can be adept at achieving congruence! And just when you thought you had a fool-proof method of detection. Unfortunately, there is no infallible system for detecting lies. But you can improve your ability to detect lies by developing and constantly refining your communication skills.