Knowledge, Truth & Certainty

by | Jan 14, 2015

How can I know the truth and how can I be certain that I know the truth?



Dear Gordon,

In the first part of my answer, absolute truth was defined as any statement that accurately reflects reality at all times and places. I concluded that 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.”

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!

Dr. Phil