This is something I had on another site since 2006, but since it was hardly ever accessed there, I thought, why not post it here as well so there would be another place from which people could choose not to read it!
Investigative Strategy and Assumptive Differences - Reliability versus True or False
The noted philosopher and logician, Bertrand Russell, at age 92, wrote that reason had its limitations. "Beware of rational argument," he reminded us; "you need only one false premise in order to prove anything you please by logic." Leading me to an illustration of how, when it comes to investigative strategies, the rational parts of our brain are more prone to error than we might have suspected:
Take for example this version of the liar paradox (also a subject of Russell's writings), which was ascribed to the ancient Greek, Epimenides the Cretan, who said that, ’All Cretans are liars.’ We have here a statement that seemingly cannot, by traditional logic, be judged either true or false. Can it be true if this Cretan is not a liar, yet can it then be false if this Cretan is not lying?
But instead of just reading that statement, imagine that you actually met Epimenides, and he said to you personally: "All Cretans are liars." Your first reaction might be to wonder why, being a Cretan, would he say that, even if he thought it was true. And secondly, does he mean all Cretans always lie, or that no Cretan always tells the truth, or no Cretan ever tells the truth?
Your "emotional" and intuitive brain areas are thus examining signals reflecting the degree of probability that the statement is or is not reliable, as reliability is the key concept here. In a face to face encounter, these parts of the brain will automatically consider multiple scenarios, such as the speaker's motives, rather than operate from a presumption that the statement will be either true or false. It's the "rational" brain's assumption that things have to be one or the other that creates the apparent paradox.
"Paradox" has been defined as an assertion that is essentially self-contradictory, though based on a valid deduction from acceptable premises. And of course there's no paradox if Epimenides is simply lying about being a liar. Or if he is simply wrong and doesn't see the contradiction implicit in his also being a Cretan. But because we can't make a valid deduction without having more evidence available, we will intuitively treat the statement as unreliable, yet not necessarily know why, or know how to resolve the apparent contradictions.
Clearly, an assumptive premise that a thing is either true or false would be the flaw in this process, and without the input from the rest of the brain that the statement may be deliberately deceptive, for example, the rational brain, given that initial premise, would have a harder time realizing that this additional aspect of assessing "reliability" can be in fact the key to the problem.
The inference to be drawn here is that a "true or false" assessment alone is not sufficient as part of a successful investigative strategy. It is reliability that we are seeking through these strategies, and the concepts of "true" and "reliable" are not interchangeable. Truth is a part of the reliability assessment, but the main component is the degree of predictability involved. The brain is essentially a predictor of consequences, and the reliability of these predictions is more important to it than assessments of whether they are simply right or wrong.
Aphorism for thought: We might find more truth in a search for reliability, than find reliability in a search for the truth.
As to the paradox per se, here's its simplest form: "This sentence is false." Is it true? If so, it's false. Is it false? If so, it's true. My own solution: It's not necessary that it's either, especially if it's both. Because it's simply true that it's false. Or not so simply.
Because it's not false that it's true.