“…To say of what is that it is, or of what is not that it is not, is true.” Aristotle
What is true? The answer is quite straightforward. True is a property of any statement referred to as a proposition or assertive phrase. All such statements have the property of either true or false. This property is not relative, but absolute. If a statement is true, it is true for everyone.
The more difficult question is what does it mean to say something is true? Philosophers have struggled with this question for at least five hundred years without coming up with a universally accepted answer. When you add the extra factors of language and its usage and understanding the problem becomes even more difficult. Bertrand Russell spent a lifetime wrestling with this problem and never solved it. I will spend what seems like a lifetime, but will only be fifteen minutes or so.
A brief philosophical answer. Initially philosophers argued that true statements have a correspondence with reality. That is, a matching up between the statement and beliefs and reality. However, this did not stand up to close scrutiny.
Another way to approach the problem is to categorize statements relative to the truth property. The first type is referred to as necessary. They are statements that are true on their face, ie. a priori. An example would be “All triangles have three sides.” The second type is contingent, based upon experience, or a posteriori statement. Their truth is dependent upon empirical data. An example would be “This triangle is blue.”
There are several modern philosophical theories of truth. The coherence theory argues that a statement is true if and only if it is consistent and fits in (coheres) with generally accepted beliefs. Truth is measured in terms of its consistency with other truths. A second theory is the pragmatic theory. It argues that a statement is true if its use is expedient, if using it leads to successful consequences, ie. if it is pragmatic. Truth is measured in terms of its practical utility.
What true isn’t! How is it misused?
Reality or perception is not subject to being true or false. Everyone’s reality is different because it is created by one’s senses gathering secondary qualitites. Galileo has told us that they are subjective.
Religion and religions concepts are not subject to be true or false. Religion is based upon faith, not science. It consists of nonfalsifiable beliefs.
The opposite of true is false, not a lie. This is not about “speaking the truth.”