A Myth About Identifying Deception

The very expressions on someone's face as they speak, observe, and react in everyday life are never a sure epistemological guarantee of anything more than that one can see a specific facial expression on display.  It is always possible for someone's true thoughts and emotions to be intentionally concealed or even unwittingly obscured by facial expressions.  In other words, there is no such thing as knowledge of what another person is thinking or feeling just by looking at their face.  The most blank face could mask deep reflection, and the most expressive face could be a facade.  The gap between minds, if other minds even exist, cannot be bridged by mere bodily observation.

It remains popular for some people to pretend like they can tell if someone is lying just by looking at them, especially if they display some specific "sign" like looking to the right or left of whenever they are supposedly lying to.  Anxious expressions, abnormal body language, and so on might also be pointed to as alleged proof (when they are not even automatic evidence of deception, much less actual proof).  There is no body language or look in someone's eye that betrays whether they are lying to someone else.  No matter how observant a person is, they can never prove to themselves that someone is or is not trying to deceive by analyzing their outward appearance or behavior.  They must instead start with a mere assumption and let it guide them to some logically unrelated conclusion.

Someone might regularly feel anxious and have their body display outward signs of this internal panic, like sweating or darting eyes, with or without any conscious effort to lie.  Someone who intentionally, knowingly lies about some philosophical or practical matter could seem very confident, very genuine, and not at conflict with himself or herself.  In no situation does it logically follow from lying that one must exhibit some visual "sign" of deception.  The truth is that outward bodily reactions to making any statement could arbitrarily seem suspicious to others, although there is no default connection between lying and giveaways other than conveying incoherent concepts.  A myth about identifying deception will still have its appeal to those willing to make assumptions.

There is also the fact that when it comes to the most important claims of all--claims of explicitly philosophical truth that are rationalistically verifiable--many people are too irrational, uninterested, and incompetent to actually realize whether they are actually lying or not about what is true and what can be known.  As such, someone could inwardly believe or verbally state the grandest lie of all (that logical axioms are not inherently true) without any physical signs that might accompany their verbalization of other lies.  Again, there is simply no absolute certainty in the assumed connection of accidentally stating something false or intentionally lying and having some physical reaction betray the telling of the lie.

Depending on the exact thing a person communicates, it is either impossible to prove someone is lying (sensory perceptions and memories could be misleading, and confirming many claims would require fully verifiable sensory perceptions and memories) or possible to prove they are lying only by recognizing a contradiction or assumption within the claim.  This, of course, is far more difficult for a typical non-rationalist to accept than the idea that they can somehow "just know" that someone else is lying because they feel a certain way or can point to an irrelevant physical reaction like sweating.  Epistemological limitations and red herrings are just not convenient for those eager to make assumptions.