Philosophical Theories of Truth and Knowledge
The Knowledge and Truth
The fundamental philosophical problem underlying the question of knowledge is the distinction between true and false, and, above all, the question of whether it is possible to reach the truth. The philosophical question of knowledge is: Can we really know?
Parmenides, in the sixth century BC, distinguished between truth and opinion. For Plato, there was only one kind of knowledge, *true*, and that knowledge is an infallible authority; the error falls within the view. For Plato and Aristotle, and generally for all ancient philosophy, to know is to know truth.
As we know, the process of knowledge involves two elements: an object and a subject. This relationship has been understood in different ways throughout the history of philosophy:
- a) If we focus on the subject, then it is he who will build the knowledge: idealism.
- b) If we focus on the object, then the outside world takes precedence over the idea and we have realism.
In the field of philosophy, there are three fundamental ways of understanding knowledge and the criterion of truth, namely:
- Idealism maintains that you cannot see the situation, but the human cognitive structure is imposed and determines the way of seeing things. There is an unbridgeable distance between what things are and what they look like to the subject; thus, the criterion and truth is in the subject and not the object.
- Realism defends the possibility of objective knowledge. You can get to see the situation as if the subject did not intervene. The world is the only source of knowledge and the only criterion of truth.
- Consensus Theories and Pragmatic Theories. For these theories, the criterion of truth is the agreement among individuals in a society. These theoretical positions may lead to relativism.
Theories of Truth
Truth is a property of language, of the statements we make about the world. The question that leads us to find the criterion of truth is: What are the conditions under which we may qualify a statement as true?
Truth as Correspondence
The classical formulation of the notion of truth as correspondence says that truth is the correspondence between the intellect and things. Correspondence or adequacy as truth is a realistic criterion of truth, since it is part of the same assumptions of realism:
- a) There is a reality independent of the subject.
- b) The subject may know the actual event.
The first to formulate the notion of truth as correspondence was Aristotle in the fourth century BC. Later, in the Middle Ages, Thomas Aquinas finally made the concept of truth as correspondence. Now, in the twentieth century, the theory of truth as correspondence was reformulated by Bertrand Russell, who redefined it as an isomorphism between reality and thought: “For a proposition to be true, there must exist in reality all the facts to which it refers.”
Finally, Alfred Tarski made this notion of truth in semantic terms, that is, in terms of meaning. The adjustment now occurs between a statement of the object language and a statement of the metalanguage. In Tarski’s formulation, language acquires a relevant role as a repository and mediator in any regard to truth. Truth is a property of language.
The Truth as Coherence
Historically, coherence theories of truth have been defended by idealistic and rationalist authors like Spinoza, Leibniz, or Hegel. For coherentism, it is not necessary to contrast the truth or falsity of a proposition with the outside world, because a proposition is true when it does not contradict the other propositions of a system or theory. The truth or falsity of a statement depends on the logical relationship it has with other statements of the system.