Truth <> Logic

Thanks to a picture forwarded to me by Joey F., who received it in an email from his lovely and gracious daughter, Heidi F., a Republican beauty if there ever was one: What is Truth? Well, the obvious at left.

Truth

Philosophers and logicians have proposed a number of broad theories about truth, which are now frequently sorted into two camps.

Robust Theories

Some theories hold in common that truth is a robust (sometimes inflationary) concept. According to these theories, truth needs explanation and is something about which significant things can be said:

The correspondence theory of truth sees truth as correspondence with objective reality. Thus, a sentence is said to be true just in case it expresses a state of affairs in the world.

The coherence theory sees truth as coherence with some specified set of sentences or, more often, of beliefs. For example, one of a person's beliefs is true just in case it is coherent with all or most of her other beliefs. Usually, coherence is taken to imply something stronger than mere consistency: justification, evidence, and comprehensiveness of the belief set are common restrictions.

The consensus theory holds that truth is whatever is agreed upon, or in some versions, might come to be agreed upon, by some specified group.

Pragmatism sees truth as the success of the practical consequences of an idea, i.e. its utility.
Social constructivism holds that truth is constructed by social processes, and it represents the power struggles within a community.

Semantic theory of truth

The semantic theory of truth has as its general case for a given language: 'P' is true if and only if P where 'P' is a reference to the sentence (the sentence's name), and P is just the sentence itself.
Logician and philosopher Alfred Tarski developed the theory for formal languages (such as formal logic). Here he restricted it in this way: no language could contain its own truth predicate, that is, the expression is true could only apply to sentences in some other language. The latter he called an object language, the language being talked about. (It may, in turn, have a truth predicate that can be applied to sentences in still another language.) The reason for his restriction was that languages that contain their own truth predicate will contain paradoxical sentences like the Liar: This sentence is not true. See The Liar Paradox. As a result Tarski held that the semantic theory could not be applied to any natural language, such as English, because they contain their own truth predicates. Tarski thought of his theory as a species of correspondence theory. Donald Davidson (philosopher) used it as the foundation of his Truth-conditional semantics and linked it to Radical interpretation in a form of Coherentism.

Subjective vs. objective

Subjective truths are those with which we are most intimately acquainted. That I like broccoli or that I have a pain in my foot are both subjectively true. Metaphysical subjectivism holds that all we have are such truths. That is, that all we can know about are, one way or another, our own subjective experiences. This view does not necessarily reject realism. But at the least it claims that we cannot have direct knowledge of the real world.

In contrast, objective truths are supposed in some way to be independent of our subjective beliefs and tastes. Such truths would subsist not in the mind but in the external object.

Relative vs. absolute

Relative truths are statements or propositions that are true only relative to some standard or convention or point-of-view. Usually the standard cited is the tenets of one's own culture. Everyone agrees that the truth or falsity of some statements is relative: That the fork is to the left of the spoon depends on where one stands. But Relativism is the doctrine that all truths within a particular domain (say, morality or aesthetics) are of this form, and Relativism entails that what is true varies across cultures and eras. For example, Moral relativism is the view that moral truths are socially determined. Some logical issues about Relativism are taken up in the article on the relativist fallacy.

Relative truths can be contrasted with absolute truths. The latter are statements or propositions that are taken to be true for all cultures and all eras. For example, for Muslims God is great expresses an absolute truth; for the microeconomist, that the laws of supply and demand determine the value of any consumable in a market economy is true in all situations; for the Kantian, "act only according to that maxim by which you can at the same time will that it should become a universal law" forms an absolute moral truth. They are statements that are often claimed to emanate from the very nature of the universe, God, or some other ultimate essence or transcendental signifier. But some absolutists claim that the doctines they regard as absolute arise from certain universal facts of human nature.

Absolutism in a particular domain of thought is the view that all statements in that domain are either absolutely true or absolutely false: none is true for some cultures or eras while false for other cultures or eras. For example, Moral absolutism is the view that moral claims such as "Abortion is wrong" or "Charity is good" are either true for all people in all times or false for all people in all times.

But don't confuse Truth with Logic. My cousin, Dr. Jenny F., is an expert in the field at Cal State, and drives a motorcycle to boot.

Logic

Logic (from Classical Greek λόγος (logos), originally meaning the word, or what is spoken, but coming to mean thought or reason) is most often said to be the study of arguments, although the exact definition of logic is a matter of controversy amongst philosophers (see below). However the subject is grounded, the task of the logician is the same: to advance an account of valid and fallacious inference to allow one to distinguish good from bad arguments.

Traditionally, logic is studied as a branch of philosophy. Since the mid-1800s logic has been commonly studied in mathematics, and, even more recently, in computer science. As a science, logic investigates and classifies the structure of statements and arguments, and devises schemata by which these are codified. The scope of logic can therefore be very large, including reasoning about probability and causality. Also studied in logic are the structure of fallacious arguments and paradoxes.

Due to its fundamental role in philosophy, the nature of logic has been the object of intense disputation, and it is not possible to give a clear delineation of the bounds of logic in terms acceptable to all rival viewpoints. Nonetheless, the study of logic has, despite this fundamental controversy, been very coherent and technically grounded. Here we characterise logic, firstly by introducing the fundamental ideas about form, then outlining in broad terms some of the most influential rival conceptions of the subject, giving a brief overview of its history and then give an account of its relationship to other science, and then go on to provide an exposition of some essential concepts.

History of Logic

While many cultures have employed intricate systems of reasoning, logic as an explicit analysis of the methods of reasoning received sustained development originally only in three places: China in the 5th century BCE, and India and Greece between the 2nd century BCE and the 1st century BCE.

The formally sophisticated treatment of modern logic apparently descends from the Greek tradition (although it is suggested that the pioneers of Boolean logic were likely aware of Indian logic (Ganeri 2001) but comes not wholly through Europe, but instead comes from the transmission of Aristotelian logic and commentary upon it by Islamic philosophers to Medieval logicians. The traditions outside Europe did not survive into the modern era: in China, the tradition of scholarly investigation into logic was repressed by the Qin dynasty following the legalist philosophy of Han Feizi, in the Islamic world the rise of the Asharite school suppressed original work on logic, and in India, though innovation in the scholastic school continued into the early 18th century, it did not survive long into the colonial period.