Different forms of the Fallacies of Presumption explained with examples

Some arguments are fallacious because they are based on unwarranted assumptions. In these arguments the error arises out of an implicit supposition of some other proposition whose truth is uncertain or questionable. The fallacy of presumption may occur when something is assumed to be true though it is not reasonable to accept it in the relevant context.

Accident:

The fallacy of accident occurs when a rule that is generally applicable is applied to an exceptional case and the exceptional character of the case is ignored. A general rule is applied when circumstances suggest that an exception to the rule should apply. This fallacy is also called the Fallacy of Ignoring the Exception. For example:

(I) The law states that one should not drive faster than 50 km per hour. Therefore, even when the road is empty and you are rushing an emergency patient to the hospital you should not drive faster than 50 km per hour.

(ii) One should return the thing one has borrowed when asked for. Therefore, you should return the pistol to its owner even when he going to commit suicide.

There is also a Converse Fallacy of Accident. It consists in assuming that what holds true under some special circumstances must hold true as a general rule. A man who refuses to take alcohol, even when asked by the doctor, on the ground that alcohol is a poison commits the fallacy of accident.

Conversely, a man has been prescribed to take alcohol when he was ill, but he reasons that it would be alright for him to continue taking it even after getting well. This man commits the converse fallacy of accident.

Begging the Question (petitio principii):

The fallacy of begging the question arises when the truth of the conclusion is assumed by one of the premises. To beg the question is to assume the very point at issue one is arguing for. Often, the conclusion is simply restated in the premises in a slightly different form.

For instance, in the argument "Since I am not lying, it follows that I'm telling the truth" the fallacy of begging the question is obvious or explicit. However there are instances where the fallacy is not obvious. In such cases the premises of the argument implicitly assume the conclusion.

Consider the following argument: "We know that gods exists, because the scriptures say so. What the scriptures say must be true, since gods have written the scriptures". This argument begs the question because one of its premises "Gods have written the scriptures" assumes that gods exist.

It can be noticed that an argument that begs the question is formally valid. The problem here is that this valid argument does not really provide support for the truth of its conclusion. An argument that begs the question will have a premise that will not be accepted by a person who questions the truth of the argument's conclusion.

Fallacy of Complex Question:

This fallacy occurs when someone demands a single answer to a complex question. This is a deceptive form of questioning, in which a single answer is demanded to what is not really a single question. This fallacy is also called the fallacy of many questions.

Consider, for example, the classic example of a complex question "Have you stopped beating your wife?", in which the respondent is asked to answer in simple 'yes' or 'no'. Either answer would lead to an apparent admission of wickedness. The following are some more examples of complex questions:

"Have you stopped smoking?"

"Where are you hiding the money you have stolen?"

"What hair dye are you using?"

"How long will you interfere in our affairs?”

These are loaded questions. Each of these questions presupposes a definite answer to another question which has not been asked.

False Dilemma:

This fallacy occurs when it is presumed that there are only two choices while in fact more options are available. This fallacy is also called "black and white thinking", because it oversimplifies the options by assuming that one of the two extreme views must be true.

The following remarks can be instances of false dilemma or black and white thinking.

Either you are my friend or my enemy.

Either you love a person or hate him.

A person is either wise or a fool.

If your are not for me then your are against me.

If you love your wife, then you will surely buy this saree for her.