Two major forms of reasoning are inductive and deductive reasoning. There also exists abductive reasoning.1 The fiction character Sherlock Holmes used the abductive form of reasoning quite often.
Induction is a form of reasoning that makes generalizations based on individual instances or observations. That is, we commonly assume certain truths to be universal truths because all our experience so far seems to indicate no exceptions.
For example, we assume that gravity will pull down on us toward the center of the Earth since we have experienced no other affect of gravity on Earth. We assume that fire is always hot because we have not experienced otherwise. However, our experience regarding the affect of gravity or the hotness of fire does not really prove anything. What are we to do? One answer is to do what we can to understand the principle or process. However, in many cases, a way to do this investigation may allude us, and our experience about a matter is the best information we have.
Deductive reasoning, sometimes called Deductive Logic, is reasoning which uses deductive arguments to move from given statements (statements that are believed to be true--which in this article are called premises), to conclusions derived from those true statements (or premises). The conclusions must be true if the premises are true. An example of deductive reasoning, given by Aristotle, is the following:
All men are mortal. (premise)
Socrates is a man. (premise)
Socrates is mortal. (conclusion)
We can also refer to this as a direct proof. A direct proof is a conclusion based upon deductive reasoning that absolutely must be true if all the premises are true—that is, the conclusion that “Socrates is mortal” is undeniable if BOTH premises are true. Any number of premises may be present. All possible conclusions drawn from them are absolutely true (with NO POSSIBILITY OF ANY FALSE CONCLUSION) if ALL the premises are true AND no logical error(s) were made in drawing conclusions from the premises. Mathematicians have formulated whole areas of mathematics describing the process of drawing such conclusions. Such logical arguments can then be written down mathematically and even entered into computers. Very complex systems of information can then be analyzed logically (deductively).
Let us look at another example of deductive reasoning:
All dogs have tails. (premise)
Rover is a dog. (premise)
Rover has a tail. (undeniable conclusion if BOTH premises are true)
What happens if we cut off Rover's tail?
All dogs have tails. (premise)
Rover is a dog. (premise)
Rover has no tail. (premise)
Conclusions
Rover has a tail. (conclusion from 1 and 2, but contradicts number 3 premise)
Rover is not a dog. (conclusion from 1 and 3, but contradicts number 2 premise)
As you can see, there is something wrong with the conclusions—there are contradictions.
So what do contradictions prove? They absolutely prove that at least one of the premises is NOT TRUE.
If we know that Rover really is a dog and if we know that Rover's tail really was cut off and that he no longer has a tail, then we can rewrite the premises and include a test statement as the following:
Rover is a dog. (premise)
Rover has no tail. (premise)
All dogs have tails. (test statement)
We again come to the same conclusions because we started with the same statements:
Rover has a tail. (conclusion from 1 and 3, but contradicts number 2 premise)
Rover is not a dog. (conclusion from 2 and 3, but contradicts number 1 premise)
Even though we can identify at least two contradictions, it ONLY TAKES A SINGLE CONTRADICTION to form what is called an INDIRECT PROOF. Furthermore, ANY CONTRADICTION implies that something is wrong with the test statement if ALL the premises (statements 1 and 2) are correct. The test statement may ALWAYS COMPLETELY BE CORRECTED by placing a NOT in front of it—that is, NOT all dogs have tails.
One other very significant fact about this is that an indirect proof is JUST AS VALID as a direct proof. We have now PROVEN (with no chance that our conclusion is wrong) that “not all dogs have tails.”
Suppose someone should write down any number of premises that they know are true, and one other test statement that is their assumption that God does not exist. Then they start drawing as many conclusions as they can from combinations of their premises with each other and with the test statement. If they ever come to a contradiction—ANY CONTRADICTION ABOUT ANYTHING while using the test statement with any of the other premises that are known to be true OR any combination of the premises and conclusions drawn from combinations of premises and the test statement, then they have CONSTRUCTED AN INDIRECT PROOF whether they realize it or not. This is because if all the premises are true, then the ONLY possibility for a contradiction exists if the test statement is actually false. Then the test statement can ALWAYS be completely corrected by placing a NOT in front of it, that is, (NOT) that God does not exist—which simply means that God DOES exist. Remember that an INDIRECT PROOF is just as valid as a direct proof. The key is making sure that all the premises are indeed true.
With regard to proving that God exists, please note that, everything in our physical world is interrelated, that is, when a thing happens or an effect is produced, the thing producing the happening or effect is also affected. For example, when someone throws a ball, the affect on the one throwing the ball is to be pushed in the opposite direction as the force on the ball. There is always an effect on the producer in the form of a change in energy, momentum, or chemical or structural state. Sometimes the effect on the producer is not immediately evident when the effect is too small for us to see visually. For example, light coming from any source (such as a light bulb or the sun) exerts a pressure on our body or anything it illuminates due to the momentum of light photons. The pressure is too small to be seen (without special laboratory instrumentation) in our everyday life. However, we can easily see it when looking at a comet. When a comet approaches the sun, its tail will ALWAYS point away from the sun regardless of the direction of its travel. This happens because the molecules or cloud of particles (such as water crystals) in its tail are extremely small so that light from the sun can move them in a way similar to the way billiard balls are moved when one ball hits another. Since the photons of light are moving directly away from the sun, the general direction of the particles will also be away from the sun—especially after the sun's photons of light repeatedly interact with the particles.
The Scientific Method
Some individuals may say that they only believe that which is subject to being proven by the scientific method, with the assumption that ALL information that can be known is possible to discover through the scientific method. They believe that if the Creator exists, that fact will be finally discovered through scientific experiments and the analyses of data. However, matter and energy, space and time, and the universe itself would be subject to the Creator that made it—not the other way around. It is possible to find evidence through science of a beginning of our universe. Furthermore, science can ONLY prove dependencies, that is, processes, circumstances, or events that are interrelated or dependent upon one another. God does NOT depend upon His creation—rather His creation depends upon Him.
However, a great deal of evidence (overwhelming evidence) can be provided for His existence. Within the realm of science, much of this evidence is composed of observations that cannot be explained by scientific methods and lead to the conclusion that for the observation to be true, a supernatural force must be behind it, or else there is some physical phenomenon or law that we are unaware of that could explain the observation. Some of these observations are so profound that the thinking person should at least allow for the possibility of God's existence—in fact after due consideration one may logically conclude that these observations constitute overwhelming proof of the existence of God.
Also, within the realm of God's written word, some of the many things that should be considered are the prophecies. After examination of evidence available about the Scripture (including information regarding when the Scripture was written), one can then believe God's word to be inspired when it is seen that the prophecies actually came true. After consideration of many profound observations, the thinking individual should also conclude that the existence of God is fact, from this point of view also. I may discuss some of these observations in a future update. One of these observations that I have already written about on this website comes from the consideration of that which is ever before us—our self-awareness, that is, the implications of the essence of self-awareness.
There are many problems that people have in accepting the existence of God. Some of them typically have to do with the “problem of evil” or the apparent age of the earth and the universe and comparing that to what “they think” the Bible says without truly searching what the Bible has to say—and especially without understanding what the Bible has to say concerning the nature of God. These individuals have a preconceived view of what the nature of God must be. If He does not fit into their preconceived view, then they reject his existence—and that is irrational. I may discuss some of these questions in a future update.
1Abduction, or inference to the best explanation, is a method of reasoning in which one chooses the hypothesis that would, if true, best explain the relevant evidence. Abductive reasoning starts from a set of accepted facts and infers their most likely, or best, explanations.