Reasoning

Reasoning is defined very differently depending on the context of the understanding of reason as a form of knowledge. The Logical definition is the act of using reason, to derive a conclusion from certain premises, using a given methodology; and the two most commonly used explicit methods to reach a conclusion are deductive reasoning and inductive reasoning. However, within idealist philosophical contexts, reasoning is the mental process which informs our imagination, perceptions, thoughts, and feelings with whatever intelligibility these appear to contain; and thus links our experience with universal meaning. The specifics of the methods of reasoning are of interest to such disciplines as philosophy, logic, psychology, and artificial intelligence.

Types of logical reasoning
In deductive reasoning, given true premises, the conclusion must follow and it cannot be false. This type of reasoning is non-ampliative - it does not increase one's knowledge base - since the conclusion is inherent to the premises. A classical example of deductive reasoning are syllogisms for example:


 * all humans are mortal,
 * Socrates is a man,
 * therefore, Socrates is mortal.

In inductive reasoning, on the other hand, when the premises are true, then the conclusion follows with some degree of probability. This method of reasoning is ampliative, as it gives more information than what was contained in the premises themselves. A classical example comes from David Hume:


 * The sun rose to the east every morning up till now,
 * therefore the sun will rise to the east also tomorrow.

A third method of reasoning is called abductive reasoning, or inference to the best explanation. This method is more complex in its structure and can involve both inductive and deductive arguments. The main characteristic of abduction is that it is an attempt to favor one conclusion above others by either attempting to falsify alternative explanations, or showing the likelihood of the favored conclusion given a set of more or less disputable assumptions.

A fourth method of reasoning is analogy. Reasoning by analogy goes from a particular to another particular. The conclusion of an analogy is only plausible. Analogical reasoning is very frequent in common sense, science, philosophy and the humanities, but sometimes it is accepted only as an auxiliary method. On inferences by analogy, see Juthe, 2005.