What is Truth, and How Can I Be Certain That I Know the Truth?


Question: What is truth, and how can I be certain that I know the truth?

That’s a deep one! Buckle in. There are, I think, three parts to this question: truth, knowledge, and certainty.


Let’s begin by getting a handle on the word “truth.” We use the word “truth” in at least two ways. If it is raining outside and I say, “It’s raining outside now,” I’m telling the truth.

However, that statement will cease to be truth as soon as it stops raining. This may be called “situational truth.” Situational truth is any statement that accurately reflects reality in a given, limited situation. Many of the truth claims we make are of this sort.

We also use the word “truth” when we’re referring to “absolute truth.” Absolute truth is any statement that accurately reflects reality at all times and places. Some statements are always or absolutely true by virtue of the definitions of the terms used.

For example, it is always true that circles are round and that the sum of the angles of any Euclidean triangle is 180 degrees. Other statements are absolutely true by virtue of the nature of the things to which they refer. For example, the statements “God is wise” or “God is good” are always true because of the nature of God.

When Jesus said to Philip, “I am the way, the truth, and the life,” he did not mean that he is “a statement that accurately reflects reality.” Nor did he it mean that “truth” is a person, though this is nearer the mark. Jesus meant that he is the person who is the source of all truth.

He is the absolute, unchanging, and permanent source of all that is. He created all things (John 1:3). He sustains all things (Heb. 1:3). Since he is the source and sustainer of all reality, all that he says about reality is true—absolutely true.

Since Jesus is the source and sustainer of all reality, all that he says about reality is true—absolutely true.

It has been in vogue for the past 50 years to deny that absolute truth exists. But such a denial is self-refuting: Is it absolute truth that absolute truth does not exist? Faced with this obvious contradiction, radical truth-deniers retreat to a softer, more subtle denial. They shift to the ground of uncertainty, saying, “I don’t know whether absolute truth exists or not, and I don’t know how I can know it.” That brings us to the second part of our question: How can I know?


Before trying to answer how we can know the truth, let’s ask a bigger question: how can we know anything? In order to know anything, we must have some means of perceiving both ourselves and the objects around us and must exercise belief about our perceptions. Perhaps that sounds strange, but it is as necessary for the atheist as it is for the theist. The atheist must believe his senses can be trusted.

He must believe that there is a reality to perceive, consider, and experience. He must believe that his mind can produce conclusions that reflect reality accurately. To deny such basic beliefs (truths) is logically incoherent and, again, self-refuting.

The very first chapters of God’s word tell us how it is that we can believe and so know: the Triune God made us in His image.

The very first chapters of God’s word tell us how it is that we can believe and so know: the Triune God made us in His image (Gen. 1:27) with the capacity to have knowledge, and hence knowledge of reality as it is—just as God knows reality (Gen. 3:22). When what we believe about reality is accurate, we believe the truth. When we can justify our accurate beliefs about reality, those beliefs count as “knowledge.” The short way of saying this is “knowledge is justified true belief.”

Certainty in Our Knowledge

Once we understand that all knowledge begins properly with belief, we can then proceed to the three avenues through which we acquire and justify our beliefs about reality: observation, reason, and authority.

When you observe the world around you, you aren’t observing all of reality, but what you are observing is real. This is why science is possible. Using the scientific method of observation, testing, and repetition, we learn much truth about the world God created. However, observation has its limits. It is limited by our finitude.

We cannot be everywhere and observe everything. All statements based on observation must be conditioned by this fact. Further, observation by itself cannot tell us how our observations are related. It can’t tell us the difference between cause and effect. To make such connections we must use reason.

Reason, a key part of the image of God in us, is the second avenue through we gain knowledge. Through reason, we are able to evaluate and understand the relationship between events, ideas, people, qualities, and so on. We use reason to identify how an author connected his words and sentences into meaningful ideas.

Most importantly for knowing truth, we use reason to draw conclusions from observations and to identify whether those conclusions are valid or invalid, necessary or potential. For example, Paul says that observation of the world leads to the reasonable conclusion that there is a Creator God who is eternal and powerful (Rom. 1:20).

Authority is the third avenue through which we obtain knowledge. Since each of us is limited in our time and opportunities to learn through observation and reason, we are largely dependent upon others who have acquired justified true beliefs and teach them to us. Much of what we “know” has been received from authorities: teachers, parents, literature (print/digital), and pastors.

Our belief that Scripture is God’s word is rooted in all three of these avenues of how we acquire and justify our beliefs. First-century men and women heard Jesus claim to be God’s Son (Luke 22:70-71), to be equal with God (John 5:18). They listened to him predict that he would suffer, die, and rise from the dead three days later (Luke 9:22). Over five hundred of them observed him alive after his resurrection (1 Cor. 15:6). From Jesus’ fulfilled prediction of his resurrection, they reasoned that he must be who he claimed to be (1 Cor. 15:20ff.).

Based, then, upon Jesus’ authority as the risen Son of God, we accept his instruction to believe “all that the prophets have spoken” (Luke 24:25), that “Scripture cannot be broken” (John 10:35), and that the Holy Spirit would guide the apostles into all the truth (John 16:13).

Knowledge of absolute truth and absolute certainty regarding such knowledge must never be confused. Some claim that one must have absolute certainty to know absolute truth. This is false. Infallible confidence based upon a comprehensive awareness of reality (absolute certainty) is possible only for God.

In no sphere of life can we or do we have “absolute” certainty. Rather, we operate in all spheres of life based upon reasonable certainty. This is, in fact, the way God requires us to operate (Matt. 18:16).

The Scriptures teach that God is the universe’s ultimate authority. He knows reality perfectly, and He has revealed to us much about reality in His word. Thus, it is through His word and upon the basis of His authority that we can have certain knowledge of absolute truth.

Within His infallible word, God has provided us all we need to have an unshakeable confidence regarding our knowledge of how to live a godly life that will lead us to His heavenly kingdom (Heb. 12:28; 2 Pet. 1:3). Praise God!

Originally published in God’s Revivalist. Used by permission.

Philip Brown
Philip Brownhttp://apbrown2.net
Dr. Philip Brown is Graduate Program Director and Professor at God's Bible School & College. He holds a PhD in Old Testament Interpretation from Bob Jones University and is the author of A Reader's Hebrew Bible (Zondervan Academic, 2008).