Reasoning Methods and Common Errors
Types of Reasoning
Deductive Reasoning
Deduction and induction. If we start from an accepted and reliable premise and infer partial conclusions, we use deductive reasoning. Deductive reasoning is useful because, if well-constructed, the conclusions are true. A good argument follows from reliable premises. Deductive reasoning does not question if it is true or false, but whether it is correct or incorrect; that is, if the conclusion follows from the premises without doubt.
Inductive Reasoning
Induction, however, starts from a series of partial events that repeat and can be observed in a regular form. Following this series, a general conclusion is inferred. Inductive reasoning is based on the repetition of a series of premises; therefore, the quality of the induction depends on the amount of premises we have.
Reasoning by Analogy
Another common form of argumentative speech is reasoning by analogy. It consists of arguing from a starting point that is similar to the situation or event one wants to argue about.
Rawls’ Theory of Justice
The American philosopher Rawls developed a theory of justice that places emphasis on human rationality as a key component for determining what is fair. His starting hypothesis is that all people are reasonable and, therefore, can decide what is just and what is fine.
Rational vs. Reasonable
A rational individual would be selfish; that is, they would desire what we consider only by considering their own benefit. A reasonable person would take into account the special interests of others and seek cooperation, even if it might be detrimental to themselves.
Rawls’ Two Principles
If we keep these two principles in mind, a stable and fair society can be achieved. According to Rawls, justice in a society and its good results are the fruit of the balance between individual interests and the interests of others. Rawls defines two principles: first, that all people have the most liberties and rights; and second, that economic inequality should always benefit everyone. To ensure this just situation, the state must try its utmost to achieve the well-being of the people within a societal situation. According to Rawls, if the state promoted equal incomes for all, individuals would not have much incentive to work. Rawls always considers natural competition to benefit the least favored.
Common Logical Fallacies
- Paradox: Reasoning with two statements that contradict, therefore cannot be real.
- Petitio principii: To say the same premise twice, alternating word order.
- Ad hoc: It is a statement that is used to save a definition or something that was predicted.
- Ad hominem: When it comes to rebut what one person says by disqualifying that person for their sex, nationality, race, or any other circumstance.
- Ad verecundiam: When, to assert one’s opinion, one resorts to the argument that the same view has been held by some important person or a majority of people.
- Ad populum: Is to argue with reference to the feelings, prejudices, and interests of listeners, without any justification whatsoever.
- Tu quoque: When it is intended to be right because the other has made the same mistake we did.
- Inadequate Generalization: When you get a generalization from insufficient premises for this. This is an improper induction.
- False Cause: It is said that something causes something else because what has happened once, and you try to establish a necessary connection between these two facts without basis for it.
- Fallacy: An argument that seems right but is wrong.
- Sophism: Is a refutation in order to defend something false, confusing the listener or interlocutor by a lie in the argument, which may consist in exposing false premises as true.
- Paralogism: It is a false argument or reasoning, which arises without a will of deception. Unlike a fallacy, the paralogism does not depend on malicious confusion in terms, but an error of reasoning.