Knowledge, Truth and Certainty

by | Jan 14, 2015

What is truth, and how can I know that I know it?



Dear Gordon,

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.

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 (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.”

In my next column, I’ll cover knowing truth and certainty in our knowledge.

Dr. Phil