Can we prove that God exists?

A common question posed to Christians, indeed to theists of any stripe, today is whether or not one can "prove" that God exists. While this is a legitimate question to ask, some precautions and clarifications are necessary in responding to theses inquiries.

The first thing to point out is that the term "prove" must be clarified. Technically, to prove something is to show that it is the case with mathematical certainty. In other words, proving something is like showing that we can be as certain of a claim as we are that 2 + 2 = 4. Often, however, that is not what many people mean by "proof" while many others may mean precisely that. This can cause a breakdown in communication.

Because most of the opponents of Christianity tout themselves as relying on "reason" rather than faith (as if the two were mutually exclusive), let's take a look at the various types of reasoning that we can attempt to apply to the investigation of the claims of Christianity. There are three methods of reasoning that we will look at. The first of which is called deductive reasoning.

Of the three forms of reasoning, deductive reasoning is the only form of reasoning that results in the mathematical certainty we just talked about. The weakness of deductive reasoning, however, is the fact that we can learn nothing new from it. With deductive reasoning, all we can do is determine with mathematical certainty what we already know to be true. For example, it is common in philosophy classes to use the following syllogism to teach deductive reasoning:

All men are mortal.
Socrates is a man.
Therefore, Socrates is mortal.

While based on such a syllogism we can arrive at the conclusion that Socrates is mortal with the same amount of certainty we can have the 2+2 = 4 given that both of the premises are true, we have not actually learned anything new. In order to learn new things, this is where the other two forms of reasoning come into play.

The next form of reasoning we will look at is called inductive reasoning. Inductive reasoning is based on common experience. For example, if I were to make the claim that all ravens are black, this claim is based on the experience that all ravens I have ever seen or heard of have always been black. Therefore, using inductive reasoning, we would say "since all ravens we have ever experienced are black, it is highly probable that all ravens are black." Notice, however, that this gives us something that is probably true, not certainly true. This type of reasoning is used by scientists all the time throughout history. It is one method of reasoning that allows us to actually learn new things. But we can never be mathematically certain of our conclusions, only that our conclusions are highly probable.

The third form of reasoning is called abductive reasoning. This is also referred to as "inference to the best explanation." This is the form of reasoning that many detectives use, and also parents, in order to determine events that actually took place. Like in inductive reasoning, with abductive reasoning, we can only determine what is most probably true. In other words, we can determine what is the best explanation for a set of facts. But we cannot determine whether or not that inference is actually true and is necessarily the case.

Abductive reasoning is often used in court cases and by law enforcement agencies. It is used to determine what set of events is probably true. Often circumstantial evidence is vitally important to this form of reasoning. That, however, is not the only common use for abductive reasoning. Another common use for abductive reasoning, is parenting. Often, parents have to determine who broke a particular dish. Or, they have to determine who left the lights on or who made a mess in the room or who is to blame for the crying and fighting upstairs.

In fact, abductive reasoning is probably the most commonly used form of reasoning. While it is been popularly noted that Sherlock Holmes was a major proponent of deductive reasoning, it is actually the case that he used abductive reasoning far more than deduction.

Another important aspect of abductive reasoning is the fact that it allows for other plausible explanations f the facts. Rather than eliminating all other explanations, the goal of abductive reasoning is merely to identify the one the best explains the facts. Other explanations can be offered and even be plausible. But the best explanation is determined by identifying the one that has the best explanatory scope, the best explanatory power, the least ad-hoc parts, etc.

So, to summarize the three types of reasoning, deductive reasoning leads to a conclusion that is 100% certain but gains us no new knowledge. Inductive reasoning helps us to make predictions based on past experience and helps to increase knowledge based on probability. Abductive reasoning helps us explain past events by looking at the facts and inferring the best explanation of those facts.

For more resources:

• Cold Case Christianity - J. Warner Wallace
• The Case for the Resurrection of Jesus - Gary Habermas
• Can You Prove God Exists - Bible.org