Reason

===Logical reasoning methods and argumentation===
{{main|Logical reasoning}}
A subdivision of [[philosophy]] and a variety of reasoning is [[logic]]. The traditional main division made in philosophy is between [[deductive reasoning]] and [[inductive reasoning]]. [[Logic|Formal logic]] has been described as ''the science of deduction''.<ref>{{cite book|last=Jeffrey|first=Richard|year=1991|title=Formal logic: its scope and limits|edition=3rd|location=New York|publisher=McGraw-Hill|page=1}}</ref> The study of inductive reasoning is generally carried out within the field known as [[informal logic]] or [[critical thinking]].

====Deductive reasoning====
{{Main|Deductive reasoning}}
Deduction is a form of reasoning in which a conclusion follows necessarily from the stated premises. A deduction is also the name for the conclusion reached by a deductive reasoning process. A classic example of deductive reasoning is evident in [[syllogism]]s like the following:
{| {{Table}}
! Premise 1
| All humans are mortal.
|-
! Premise 2 
| Socrates is a human.
|-
! Conclusion 
| Socrates is mortal.
|}
The reasoning in this argument is deductively [[Validity (logic)|valid]] because there is no way in which both premises could be true and the conclusion be false.

====Inductive reasoning====
{{Main|Inductive reasoning}}
Induction is a form of inference that produces [[category of being|properties or relations]] about unobserved objects or [[type (metaphysics)|types]] based on [[event (philosophy)|previous observations or experiences]], or that formulates general statements or [[law (principle)|laws]] based on limited observations of recurring [[phenomena]]l patterns.

Inductive reasoning contrasts with deductive reasoning in that, even in the strongest cases of inductive reasoning, the truth of the premises does not guarantee the truth of the conclusion. Instead, the conclusion of an inductive argument follows with some degree of [[probability]]. For this reason also, the conclusion of an inductive argument contains more information than is already contained in the premises. Thus, this method of reasoning is ampliative.

A classic example of inductive reasoning comes from the [[empiricist]] [[David Hume]]:
{| {{Table}}
! Premise
| The sun has risen in the east every morning up until now.
|-
! Conclusion 
| The sun will also rise in the east tomorrow.
|}

====Analogical reasoning====
{{Main|Analogical reasoning}}
Analogical reasoning is a form of inductive reasoning from a particular to a particular. It is often used in [[case-based reasoning]], especially legal reasoning.<ref>{{cite book |last=Walton |first=Douglas N. |title=Systematic Approaches to Argument by Analogy |chapter=Argumentation Schemes for Argument from Analogy |author-link=Douglas N. Walton |date=2014 |editor-last=Ribeiro |editor-first=Henrique Jales |series=Argumentation library |volume=25 |location=Cham; New York |publisher=[[Springer Verlag]] |pages=23–40 |isbn=978-3319063331 |oclc=884441074 |doi=10.1007/978-3-319-06334-8_2|chapter-url=https://scholar.uwindsor.ca/crrarpub/15 }}</ref> An example follows:
{| {{Table}}
! Premise 1
| Socrates is human and mortal.
|-
! Premise 2
| Plato is human.
|-
! Conclusion 
| Plato is mortal.
|}

Analogical reasoning is a weaker form of inductive reasoning from a single example, because inductive reasoning typically uses a large number of examples to reason from the particular to the general.<ref>{{cite encyclopedia |last=Henderson |first=Leah |title=The Problem of Induction |encyclopedia= The Stanford Encyclopedia of Philosophy |year=2022 |url=http://plato.stanford.edu/entries/induction-problem/ |publisher=Metaphysics Research Lab, Stanford University }}</ref> Analogical reasoning often leads to wrong conclusions. For example:
{| {{Table}}
! Premise 1
| Socrates is human and male.
|-
! Premise 2
| [[Ada Lovelace]] is human.
|-
! Conclusion 
| Ada Lovelace is male.
|}

====Abductive reasoning====
{{Main|Abductive reasoning}}
Abductive reasoning, or argument to the best explanation, is a form of reasoning that does not fit in either the deductive or inductive categories, since it starts with incomplete set of observations and proceeds with likely possible explanations. The conclusion in an abductive argument does not follow with certainty from its premises and concerns something unobserved. What distinguishes abduction from the other forms of reasoning is an attempt to favour one conclusion above others, by subjective judgement or by attempting to falsify alternative explanations or by demonstrating the likelihood of the favoured conclusion, given a set of more or less disputable assumptions. For example, when a patient displays certain symptoms, there might be various possible causes, but one of these is preferred above others as being more probable.

====Fallacious reasoning====
{{Main|Fallacy|Formal fallacy|Informal fallacy}}
Flawed reasoning in arguments is known as [[fallacy|fallacious reasoning]]. Bad reasoning within arguments can result from either a [[formal fallacy]] or an [[informal fallacy]].

Formal fallacies occur when there is a problem with the form, or structure, of the argument. The word "formal" refers to this link to the ''form'' of the argument. An argument that contains a formal fallacy will always be invalid.

An informal fallacy is an error in reasoning that occurs due to a problem with the ''content'', rather than the form or structure, of the argument.