One major way to use reason is to learn the facts and what they are and then use the explanation for the facts that is most consistent with the facts. That will be the simplest explanation. The simplest explanation can be a very complex one depending on the circumstances. This thinking is what Occam's Razor is all about.  It does not matter what field of study it is, be it religion or ethics or science, the simplest explanation is the best.  If the Razor is for science not religion as some say then what about religions that use it?  If science looks for the straightforward explanation and religion does not then clearly they are using different methods - science is using a good method and religion a bad one.  The two would be fundamentally incompatible.
A fallacy is an error in logic that looks like sound logic. In the interest of peace and self-confidence everybody needs to know what the most common fallacies are and uproot them from their minds. When you are confident that you can be right your self-esteem grows. People have great regard and trust in the person who thinks carefully before they speak.

If most people agree on some teaching that does not show it is true. The majority have erred and detested the truth countless times. We must remember how far out people – even experts can be. Do not use the huge scale of a view’s supporters to try and prove that any view is right for the majority or what is supposed to be the majority are often wrong and people often judge without thinking properly and are often more interested in justifying their prejudiced feelings than in reason. Remember, quoting learned scholars in your support proves nothing for your opponents can do the same.

Circular reasoning is a popular fallacy and upon it religion invariably depends. It says that X is true for Y says so and Y is right for X is true. You could prove you don’t exist with that logic! It is lying for it equates a guess with a proof and disguises it as such. It makes a guess and then works out something from the guess and says it is therefore proven when it is not proven for it is based on a guess and you would not be guessing if the guess was a proof. For instance, to tell somebody that the reason she can see through a window is because it is transparent is not an answer. That is begging the question for she wouldn’t be saying she saw through the window unless it was transparent. That is circular reasoning, she saw through the window because it was transparent.

Religion, for example, says that God exists because he does miracles and miracles show God exists because they are from God but all miracles would prove is that some force created them but not what that force is or what it is like morally. Miracles would need to show that God is a desirable belief before we could trust them and they cannot do that. The argument doesn’t rest on anything proven but just hangs midair and its failure shows that miracles can’t be from God when they encourage such bad logic.

If A precedes B then A does not necessarily cause B.

Every statement made by a habitual liar need not be untrue. You will have to neither believe it or disbelieve. Many think a statement can be disproved by proving that the people making it were bad. That is an error for they are the ones that are bad not necessarily the statement.

Do not assume that something you are told is untrue just because those speaking to you fail to prove that it is true.

If you have had bad experiences with policemen then do not say that all policemen are bad for your experience of them is limited and they can’t all be bad. Tarring everybody with the same brush is a major cause of racism which plays upon fear of new people who look different.

The parts do not necessarily have to have the same quality as the whole. A good football team can have some bad players and good players and bad players may make a good team. If all the members of a team are good that does not mean that the team is good. The same if you substitute bad for good. And the team being good does not mean that all the members are good either. The members might be terrible but might work well together.
Do not judge any statement until you are sure there is no ambiguity in it. Taking the wrong interpretation and the thing in the wrong sense will throw you off. For example, Jesus, Son of God is God. I am a son of God therefore I am God. Here we mean son of God in different ways and not noticing that gives us the wrong conclusion.

To think that “if x then z, z therefore x “is wrong as is to think that “if x then z, not x therefore not z”.

The most dangerous fallacy of all is letting pity and your feelings tell you what to think. Reason should be the boss. I am not saying you should have no feelings. You will always have feelings but you should think clearly and try to be right as best you can and let your feelings become the representative of reason for you. The intelligent person when hearing something silly will feel that there is something wrong with it even before he has the chance to think because he is in the habit of letting his thinking program his feelings and that is how it should be with regard to emotions. To let emotions rule reason is a disorder and is abnormal and dangerous.
It is said that if we are rational, we will ignore our feelings. Being rational is good. But being rational and enjoying it and feeling good about it is far better. Our feelings will spur us on to passionate adulation for reason and truth. Being rational and emotional are not only compatible but desirable. Our feelings and desires must direct and fuel our rationality.

Truth is stating what is the case though some eccentric creatures maintain that it is what you wish or think or feel to be true. You can prove that they are being unintelligent right now by wishing, thinking and feeling that you never existed.

Now that we have met some of the fallacies let us remember that one false principle can do much damage to the truth and be the foundation of many more. Learn to reason and take care with it for it is dangerous when it is mistaken. Error degrades for the mind is meant to be right.