Truth

What is it?

Stephen Pinker very nicely describes information in How the Mind Works in this way:

Information is a correlation between two things that is produced by a lawful process, as opposed to coming about by sheer chance. We say that the rings in a stump carry information about the age of the tree because their number correlates with the tree's age. The older the tree, the more rings it has. And the correlation is not an accident, but is caused by the way trees grow. Correlation is a mathematical and logical concept. It is not defined in terms of the stuff that the correlated entities are made of. Information itself is nothing special. It is found wherever causes leave effects.

If we accept that information is a correlation between two things, specifically a representation (an abstract, compressed form) and a referent (the entity being referred to), then the truth value of a given amount of information is based on the strength of the correlation between the representation and the referent.

In Pinker's example, the truth value of the information contained in the tree rings would be very high if there were a strong correlation between the growth of the rings and the age of the tree. However, if some other event added or distorted the rings such that the correlation was low, then the corresponding truth value would be low.

This concept of truth is less in line with the black-and-white, bivalent classical Greek logic, and more in line with the notions of fuzzy logic, where truth is an analog continuum and not an all-or-nothing proposition. To say something is true is to say that something is true to a certain extent or with a particular confidence level, with the understanding that truth is an ideal, and that no representation can ever be 100% true.

The most common representation/referent relationships we are familiar with are the words with which we communicate. Any given word does not have a concrete, unambiguous mapping to the real-world concept it is meant to refer to. However, some combinations of words, or messages, are truer than others, that is, having a stronger correlation with the actual things they are referring to. A lie or falsehood is a message intended to refer to the opposite of the actual state of the world. The truth value of a message can also be lowered by the omission of relevant facts.

However, this conception of truth is not restricted to statements, such as "All men are mortal." Any correlation can be evaluated on the basis of its strength. If a particular metal rod is exactly one meter long, we could evaluate the truth value of the statement "The rod is 1.1 meters long," and the truth value would be reasonably high. However, we could also measure a piece of string along the rod and cut it to use as a representation of the rod. The truth value of the representation (in this case a physical object and not a statement) would depend on the correlation between the lengths of the string and the rod.

Thus, truth is a graded measure of correlation between two entities, regardless of the medium of either the representation or the referent. The next section will discuss the means by which an agent acquires information, and how they may go about evaluating the truth value of correlations in the world.