In just about all societies, there is an inherent assumption of truth-telling when people communicate. Equally, there is both a legal and an ethical prohibition on lying, and a social ostracization of liars.
We make three general assumptions in communication: 1) that the person speaking has information which at least they believe is true, 2) that the person speaking is attempting to communicate that information, and 3) that the person speaking is attempting to communicate that information accurately. These three add up to the assumption of truth-telling. So long as we assume truth-telling, we can engage in charitable reading, fill in the blanks, or correct apparent discrepancies. This makes communication of content possible, by allowing us to focus on the content, while making the fact-checking function a background issue. Thus, with truth-telling assumption, we focus on the forest – not the trees.
By contrast, professions that do not assume truth-telling (like lawyers, interrogators, etc.) offer no charitable reading. They do not listen for the content, but for the problems in phrasing, accuracy of expressions, mechanical use of language, etc. They do so on the assumption that the speaker is either outright lying or misleading the audience. Without assuming truth-telling or charitable reading, communication of content is lost, because the entire focus shifts away from the content to the otherwise mundane factors. We cannot see the forest, because we’re conducting a thorough analysis of each tree and shrub.
Interestingly, it seems that the absence of the truth-telling assumption leads not just to a slower communication, but effectively leaves us unable to communicate. So long as the statements made by the other side remain suspect, we can never take them to represent the truth, and they can always be interpreted as just another way of deception and obfuscation. Consequently, we get stuck in a scenario where whatever the other party claims, it gets read as “that’s just what a liar would say!” Even when information is verified, we see it as an instance of, perhaps, lulling us into a false sense of security, or more generally a ploy to be used in a later lie.
Once the assumption about truth-telling is lost, there seems to be no way of getting it back.
A good example can be found in the use of torture to extract information. Torture itself is premised on three ideas: 1) the person being tortured has information, 2) the interrogators can tell apart truth and lies, and 3) the interrogators know when there is no more information to be had. The purpose of this kind of torture, then, is to incentivize truth-telling by a person who otherwise lies – at least about having information. This means that, starting with their initial claim of ignorance, we no longer believe the person is telling the truth. However, as has been demonstrated by a variety of failed attempts at information-gathering by torture, there is no way of reestablishing the truth-telling position. Despite the hundreds of hours of torture, year after year, it is later confirmed by outside sources that, the subject not possess information, that they’re not even affiliated with the terrorist organizations we were sure they were a part of, and that their arrest was a matter of mistaken identity.
Here lies the major problem of lying: it undermines the entire structure of functional communication, and makes impossible the reestablishment of the truth-telling assumption. Lying undermines the entire social basis of civilization, which relies on cooperative efforts for its progress and functioning. It is for this reason (among others) that labeling a person a “liar” is seen as such a harsh social blow. It is also the reason why every religion has made lying prohibited and some form of a hell-worthy trespass (or its equivalent).
This problem expresses itself in many ways, and in a variety of settings. However, the behavior of addicts provides a well-known and clear example. When addiction gets bad enough, the addicts will draw on the truth-telling assumption of others, in order to manipulate them, and find a way to fund their habit. However, once the addict is exposed as a liar, they can no longer be trusted. Consequently, they are forced out onto the fringes of society, with the path back being all but impossible. That fringe segment is itself populated with individuals whose truth-telling cannot be assumed even by their fellow outcasts. This creates a kind of nightmare Hobbesian state of nature, where the driving forces of such a society are the “base” urges, but it is impossible to create a coherent sense of social order and move out of the kind of life that is nasty, brutish, and short.
By comparison, other systems of ostracizing people, such as prisons, do not have the same implications. Inside the prisons, there is a series of collectives, where participation serves to protect the individual. Outside the prison, some aspects of society – at least friends and family – tend to reengage with the former prisoner, and the society at large at least pays lip service to the idea of reform through incarceration. Thus, even criminals are afforded a better social status than exposed liars.
Finally, it is worth noting what lying actually is – i.e. why people lie.
While the specific goals of lying are diverse, the underlying (pun intended) factor remains the same. We lie if telling the truth will not produce the desired results. When our goals are such that, if we were to disclose them others would refuse to participate in them, we resort to inventing the kinds of fictions that we think the audience would need to hear, in order to go along with our goals. Sometimes those lies are proactive (e.g. Bernie Madoff), other times they’re reactive (e.g. “it wasn’t my fault!”). Either way, lying is a means of manipulating the other for our benefit – by providing them false information on which they make their decision.
Consequently, lying requires us to place our desires above the most basic social standards, demonstrating a complete disregard for other individuals and society as a whole, so long as our desires are met. When viewed in this light, it is little wonder that people branded as liars become social outcasts (at least traditionally). Additionally, it also explains the reason why religious positions make lying a hell-worthy trespass: to lie is to place one’s own desires above the word of God, and is thus a form of disbelief, heresy, and worship of false gods (in this case, it is the worship of one’s desires, since they apparently override God). A rather extreme example can be found in the story of Moses, where the Pharaoh claimed to be God, and as result of that claim made the people believe that he was justified in his actions – including genocide.
This is not to say that the Deontic prohibition on lying to a homicidal maniac should stand, but rather to note that the nature of lying is perfidious, undermines the ability to be human, and can swiftly insinuate itself into a society to the point of tearing it apart. Case in point, “fake news” is an actual phenomenon (from click-bait to outright fake stories), but one which has now entirely undermined our ability to collectively agree on truth in the media – resulting in different people having different “facts.” Once the truth-telling assumption is lost, it is unclear how the problem can be resolved, and how the people publicly exposed as liars can make their way back into the society.