What Is Truth? Agreement with Others, Correspondence to Reality, or Mere Opinion?

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The question "What is truth?" is perhaps the hardest one ever posed. Science is based on the correspondence theory of truth, namely, that truth corresponds to reality. But others say that truth is based on consensus, while others say that truth is entirely relative. So, what's the truth about truth?

When I was an undergraduate student, I majored in microbiology and minored in chemistry. And just for kicks, I nearly minored in philosophy, falling just one class short1. But these philosophy classes stuck with me for a lifetime.

From politics to our personal worldview, ultimately everything boils down to philosophy. Even science itself could not exist without its foundation in epistemology (the study of knowledge) and the philosophy of truth.

"What is truth?" is perhaps the hardest question ever asked. Pontius Pilate asked it of Jesus, didn't bother to listen for an answer, then ordered him to be crucified. Two thousand years later, we're still asking the same question.

Despite the internet, which allows us to access the entire sum of human knowledge, and the existence of organizations solely dedicated to fact-checking, the answer remains as elusive as ever. Why is determining the truth so hard? In short, it's because most things that we care about don't have simple yes/no answers. "What is the capital of Virginia?" has a straightforward, fact-based answer. But, "Is the President doing a good job?" does not.

Why does this matter? Because of "fake news" and disinformation. Before we can boldly declare something to be fake or real, we need to know what we even mean by "news," which in itself depends on what we mean by "true."

What Is Truth? Correspondence or Agreement... or Something Else?

As an exercise in understanding the philosophy of truth, we were given in my introductory philosophy class six statements assumed to be true. (We weren't asked to debate whether or not they were true.) Then, we had to assign to them which of two theories -- the correspondence theory (i.e., what we claim as truth must correspond to reality) or the agreement theory (i.e., what we claim as truth must be agreed upon by members of our community who are qualified to judge) -- best explains why they are true2.

There are three things to note: First, I wrote this as an undergraduate student (about 17 years ago!), and some of my thoughts have evolved and matured since then. I indicate where with footnotes. Second, we were only given (if I recall correctly) two choices of truth theories, so the essay is over-simplified. (The part on 9/11 was especially difficult, and I would re-write it entirely today using an argument rooted in objective ethical facts.) Third, this essay helps shed a light on why we have such a problem in 2019 agreeing on what is true or what is "fake news," which is why I have reproduced it here.

Without further ado, here's the essay.


There are statements that can be made that are considered “truths” by many people, but the justification for why they are truths can vary3.  The two dominant theories on truth, Correspondence Theory and Agreement Theory, are in competition with each other as the main explanation for the question, “What is truth?”  Six different statements will be examined, and a conclusion will be reached that decides which theory most adequately explains what makes the statement “true.”

(1) No tattoos are sexy. This statement is clearly one person’s (or a community’s) opinion.  There is no fact that indicates the validity of this argument.  Therefore, this statement can only be considered true by virtue of acceptance among a wide group of people.  Many people do believe that tattoos are not sexy.  Since I also believe that tattoos are not sexy, I must be speaking a truth (or at least a truth to me), because I am in accordance with a community belief.  Thus, this statement is best supported by the Agreement Theory of Truth.

(2) Many people keep dogs as pets.  This common sense statement can be shown to be true factually.  It is a matter of fact that many people (especially in my neighborhood) keep dogs as pets.  The only part of this sentence that could be considered debatable is the word “many.”  How many is many?  It is on this point alone that the statement could be considered best supported by the Agreement Theory, however I do not hold this view.  For the most part, the statement is based on fact, and is therefore upheld by the Correspondence Theory of Truth.

(3) The HIV virus causes AIDS.  Science is based on fact.  This statement is clearly one that is backed by science, for years of research have indicated that HIV indeed is the causative agent of AIDS4.  The scientific community believes this statement, but it is not a truth in the sense of Agreement Theory (a widely accepted community belief).  The truthfulness of the belief is based on hard scientific evidence.  Thus, the Correspondence Theory of Truth upholds the validity of this statement.

(4) The attack on the Trade Center in NYC was morally wrong.  This statement on ethics is clearly a matter of opinion.  The opinion, in this case, is based on community belief rooted in religious values5.  We, as Americans, believed that the attack on the World Trade Center was the epitome of human evil.  This “truth” is based on the community belief that life is sacred (especially the lives of innocent civilians) and that murder is morally wrong.  However, the community belief of the Islamic radicals is that “jihad” and murder of “infidels” is morally sound.  Thus, a clear contrast of community beliefs is seen.  What is true for Americans differs from that of the “terrorists” because we come from different communities with different beliefs.  This is a clear cut example of a statement that is supported by the Agreement Theory of truth6.

(5) God exists.  Religion and the belief in God could be legitimately supported by both theories of truth.  While there are no hard facts that point directly to the existence of God, there is much evidence that does.  Mathematicians have used probability to show that evolution is highly unlikely7.  Observance of order in the universe also points to the existence of God.  The idea of the “unmoved Mover” is another rational thought that points to the existence of God.  While there is no absolute fact that undeniably proves God exists, there is very strong evidence that indicates that God exists.  A belief in God, therefore, could be a statement supported by the Correspondence Theory of Truth.  However, there is also a general consensus among most individuals in the world that God (or at least a Divine Authority) exists.  I make this assertion because of the vast number of religions that claim the existence of God or gods (e.g., Christianity, Islam, Hinduism, etc.)  Because of a vast worldwide community that believes in God, an individual’s belief in God is therefore justified.  This statement would then be supported by the Agreement Theory of Truth.

(6) Beethoven’s Fifth Symphony is a great work of art.  As with the first statement that was examined, this is clearly a matter of personal opinion.  There is no fact that indicates the validity of this claim, but instead the statement is a widely held belief among individuals throughout the world.  This would then correlate to the Agreement Theory of Truth.

Looking back on the way that I categorized the above statements, in can be generalized that statements of opinion (#1, 4, 6) are best supported by the Agreement Theory of Truth8.  This is because there are no solid facts to back up the statements.  These “truths” are based solely on community beliefs.  Statements on “common sense” (#2) could swing either way since “common sense” is largely dictated by culture.  However, in this case, statement #2 happens to correspond with facts.  Scientific statements (#3) will almost always be statements supported by the Correspondence Theory of Truth.  Science is based on fact, and the resulting beliefs are backed by those facts.  If a belief happens to not correspond with the facts (e.g., that the Earth is the center of the universe), then the belief is false (as opposed to being true by virtue of the Agreement Theory of Truth).  Finally, statements of religion and the existence of God (#5) could be supported by either theory.  These truths are partially based on historical facts, scientific evidence, community beliefs, and religious values.

An assessment of statements of this sort can help each and every one of us to determine what is truth.  By determining for ourselves the best definition of truth, we will be more able to separate fact from opinion and truth from falsehood.



(1) I took an eclectic mix of courses: Introduction to Philosophy, Elementary Logic, The Irrationality of Western Science, and an independent study on Greek philosophy regarding the cosmos and natural phenomena. The latter two courses were taken with a person I consider a mentor and friend, Prof. Robert Hahn, who is also my favorite teacher of all time.

(2) The agreement theory is better known as the consensus theory of truth. There are many other theories of truth.

(3) Notice that I used two spaces after each sentence. The early 2000's were barbaric times.

(4) Unbelievably, there are people who deny that HIV causes AIDS. We call them, rather uncreatively, AIDS deniers.

(5) The constraints of this assignment made it difficult to express my actual view: I believe that there are knowable ethical truths, such as "killing innocent people is wrong." That would make me an ethical or moral objectivist, and the claim that 9/11 was wrong would be based on correspondence to such objective ethical facts. But I didn't think of that at the time.

(6) Of course, this does not mean that both sides really are behaving ethically. That would be moral relativism, which I thoroughly reject.

(7) My views on this have evolved (pun intended). I adhere to the view endorsed by NIH Director Francis Collins and others like him, called theistic evolution, which finds great compatibility between Christian faith and scientific theory, including evolution.

(8) Once again, I would frame this differently in regard to the 9/11 statement. "Killing innocent civilians is wrong" is not merely an opinion; I would argue it corresponds to an objective ethical fact.