I think the easiest solution to determining wether you're being lied to or not is to take a good look at who or what is providing the information and if their/the reputation in the past has even included one proven lie then keep it simple and do not trust. If we are in fact sentient then we will in fact take in lies and truth, with the prior taking the chunk of the pie because it seems that people especially, do not feel that the truth can be handled by others when one is given the option to deliver it. It seems that the belief is that the teller is in control of the truth rather than the receiver and only the truth can be brought out if it is worth the consequence of such to the teller. What you said though, is very much worth some thought indeed as it would be a very interesting world of lies were never born. Though I think it is not possible in that it is a safe haven for the vulnerable in many scenarios.