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“Science or Faith” or “Science and Faith”? (4 of 5)

A second assumption underlying the apparent conflict between science and faith is, “I should only believe what I can prove with certainty and therefore know to be true. This is only true of science. So I choose science over faith.” When we look more closely at this assumption, it turns out to be equally false.

Those holding this assumption express it in many ways. I’ve often had conversations like this:

Steve: “Do you know God exists?”

Me: “Yes, I do.”

Steve: “Can you prove God exists? Isn’t it possible that you are wrong?”

Me:     “Yes, it is possible that I am wrong.”

Steve: “Well, then, you don’t have proof and can’t be certain. God’s existence is just something you take by faith. I am only interested in what I can prove and therefore be certain of—the facts of science.”

This assumption has a long history, playing a central role in the “Enlightenment.” It is the assumption that we can only know what we can be certain about (what we can fully prove—what we cannot be wrong about). Since only scientific claims can be proven with 100% certainty, only what science tells us is true.

As popular as this assumption is, it is wrong. It fails in at least three ways.


Response #1: Requiring Certainty is Too High a Standard for Scientific Knowledge

If we must have certainty before we can claim to know something, then this not only rules out religious knowledge, it rules out scientific knowledge as well. Surely this can’t be right.

Consider the practice of science. Scientists run experiments, collect data, and draw conclusions. However, the data never confirms or disconfirms the hypothesis completely. There is always some contrary data. For instance, the majority of experiments may confirm a hypothesis, but a few experiments do not. Most of the evidence in a trial points to the defendant’s guilt, but there is some evidence that seems to vindicate him. Even dentists aren’t certain about chewing sugarless gum: Only “Four out of five dentists recommend Trident.”

If we require 100% certainty to declare something scientifically proven and therefore something we know, we cannot claim to have scientific knowledge of anything, since nothing meets this standard. Actually, scientific proof is not based on 100% certainty. It is based on the preponderance of evidence that makes a scientific hypothesis more probable than not. That which the majority of data supports is proven, and counts as scientific knowledge.

Once we lower the “bar” for scientific proof and knowledge from certainty to probability based on the majority of data, the distinction between scientific knowledge and religious knowledge evaporates. Similar to scientific beliefs, no religious belief can be proven with 100% certainty. But religious beliefs can be proven based on the majority of evidence, whether it is evidence for God existing, Jesus being God, the Bible being God’s revelation, and so on. Like scientific knowledge, religious knowledge is also based on the preponderance of evidence that makes a religious belief more probable than not. That which the majority of data supports is proven, and counts as religious knowledge.

So science and faith are on equal footing in this regard. We can have proof and knowledge of both scientific and religious truth claims without being 100% certain. In both cases, our knowledge is based on what the majority of evidence supports. This is one reason the assumption that knowledge requires certainty should be rejected.


Response #2: Requiring Certainty is Too High a Standard for Any Knowledge

In fact, the implications of this assumption are far worse. If we assume 100% certainty (complete proof) is required to know something, then we can’t say we know much of anything! All we can be 100% certain of is our thought life. However, beyond that, we can’t be certain of anything, including what those thoughts are about.

This was the dilemma René Descartes (1596-1650) discussed in his Meditations. Assuming certainty is required for knowledge, he rejected everything he might be wrong about. He may be deceived about the external world. So he no longer know it exists. He may be deceived about other persons (other minds) existing. So he can no longer know they exist. And so it continued until finally, he found the one thing he could not be wrong about: his very own thinking. He exclaimed, “Cogito ergo sum!” (“I think, therefore I am.”) Assuming 100% certainty is required before we can claim to know something landed Descartes in the pit of skepticism.

Descartes was able to climb out of this pit by reasoning that God must exist (via a form of the ontological argument, since he couldn’t reason from anything observed in the external world). He then reasoned that since God exists, God would ensure that his senses and intellect would give him knowledge of what is outside his mind. And, voilà, all of reality is back for Descartes!

However, for many who follow Descartes into the pit of skepticism by agreeing that one needs 100% certainty to have knowledge, few can climb back out with him. If they don’t believe that his ontological argument for God’s existence works, they find themselves forever trapped in an all-encompassing skepticism about everything outside their mental life. This is indeed a sad way to live.

The good news is that most don’t follow Descartes into this pit of skepticism in the first place. Almost everyone intuitively understands that we know many things without having 100% certainty. For instance, when you get into your car you cannot be 100% certain that you will not die in an auto accident. But you weigh the probabilities, and know, based on these probabilities, that you will be able to make the meeting at 10:00. Similarly, when your wife tells you she loves you, you know this to be the case based on all the evidence available to you, though there is always the remote possibility she is lying.

The point is that none of us require 100% certainty to claim we know countless things each day. We do know many things, including truths about the world around us and about other people.

This is a second reason to reject the assumption that “I should only believe what I can prove with certainty and therefore know to be true. This is only true of science. So I choose science over faith.”


Response #3: Requiring Certainty May Cause Us To Miss Reasons to Believe

There is yet a third reason to reject this assumption. It may turn out that by assuming this, we are less able to see the evidence we are seeking.

It is a known fact that our attitudes and pre-conceived ideas have an important influence on what we do and do not see. This is one of the points philosophers of science make when talking about “paradigm shifts.” If all scientists in a given field are accustomed to interpreting data one way because they are certain their theory is correct, it is hard to “see” new data which contradicts their prevailing paradigm.

This is also true concerning belief in God. If someone has a preconceived notion that nothing counts as evidence for God’s existence that is not completely proven and therefore known with 100% certainty, then he will miss much of the evidence God has provided. A condition of belief may be the desire to find out if God exists, and apply the same standard applied to all other areas of knowledge—requiring good reasons, but not 100% certainty.

Blaise Pascal (1623-62), the great French mathematician, summed this up well when he observed that God has provided enough evidence to make his existence sufficiently clear for a true seeker, but not so much as to force those who are not truly seeking him:

Willing to appear openly to those who seek him with all their heart, and to be hidden from those who flee from him with all their heart, God so regulates the knowledge of himself that he has given indications of himself which are visible to those who seek him and not to those who do not seek him. There is enough light for those to see who only desire to see, and enough obscurity for those who have a contrary disposition. —Blaise Pascal, Pensées (New York: E.P. Dutton & Co., Inc., 1958), p. 118.

This seems to be the way God works. Furthermore, it is, in fact, what we should expect of God. We can know much of him and come to know him personally through the evidences he has provided. Yet these evidences are not overwhelming to the point of overpowering our free will. God is knowable because he is immanent (with us and revealing himself to us). Yet he is also transcendent—beyond our “frame” and ability to fully comprehend. Therefore we can have knowledge of him, yet not 100% certainty of all we know. Therein lies the mystery.



Therefore, there are at least three reasons to reject the assumption that “I should only believe what I can prove with certainty. I can prove matters of science, but I can’t prove matters of faith. So I choose science over faith.” (1) Scientific knowledge is not based on 100% certainty. It, like Christian belief, is based on probability. (2) We know nothing, outside our thoughts, with complete certainty. Therefore, this assumption leads to complete skepticism, which is unlivable. (3) Requiring 100% certainty before belief in God may well be detrimental to our belief in and knowledge of God.

For these reasons, this second assumption should be rejected. Next week I’ll discuss the third assumption underlying this popular story of the war between science and faith.

Until then, grace and peace.


For further reading I suggest Philosophical Foundations for a Christian Worldview by J.P. Moreland and William Lane Craig, Chapter 4: The Problem of Skepticism


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