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As the study of argument is of clear importance to the reasons that we hold things to be true,
logic Logic is the study of correct reasoning. It includes both formal and informal logic. Formal logic is the science of deductively valid inferences or of logical truths. It is a formal science investigating how conclusions follow from premis ...
is of essential importance to rationality.
Argument An argument is a statement or group of statements called premises intended to determine the degree of truth or acceptability of another statement called conclusion. Arguments can be studied from three main perspectives: the logical, the dialect ...
s may be logical if they are "conducted or assessed according to strict principles of
validity Validity or Valid may refer to: Science/mathematics/statistics: * Validity (logic), a property of a logical argument * Scientific: ** Internal validity, the validity of causal inferences within scientific studies, usually based on experiments ...
", while they are rational according to the broader requirement that they are based on
reason Reason is the capacity of Consciousness, consciously applying logic by Logical consequence, drawing conclusions from new or existing information, with the aim of seeking the truth. It is closely associated with such characteristically human activ ...
and
knowledge Knowledge can be defined as awareness of facts or as practical skills, and may also refer to familiarity with objects or situations. Knowledge of facts, also called propositional knowledge, is often defined as true belief that is disti ...
. Logic and rationality have each been taken as fundamental concepts in philosophy. They are not one of the same thing. Philosophical
rationalism In philosophy, rationalism is the epistemological view that "regards reason as the chief source and test of knowledge" or "any view appealing to reason as a source of knowledge or justification".Lacey, A.R. (1996), ''A Dictionary of Philosophy' ...
in its most extreme form is the doctrine that knowledge can ultimately be founded on pure reason, while
logicism In the philosophy of mathematics, logicism is a programme comprising one or more of the theses that — for some coherent meaning of 'logic' — mathematics is an extension of logic, some or all of mathematics is reducible to logic, or some or a ...
is the doctrine that mathematical concepts, among others are reducible to pure logic.


Forms of reasoning

Deductive reasoning Deductive reasoning is the mental process of drawing deductive inferences. An inference is deductively valid if its conclusion follows logically from its premises, i.e. if it is impossible for the premises to be true and the conclusion to be false ...
concerns the logical consequence of given premises. On a narrow conception of logic, logic concerns just deductive reasoning, although such a narrow conception controversially excludes most of what is called informal logic from the discipline. Other forms of reasoning are sometimes also taken to be part of logic, such as inductive reasoning and
abductive reasoning Abductive reasoning (also called abduction,For example: abductive inference, or retroduction) is a form of logical inference formulated and advanced by American philosopher Charles Sanders Peirce beginning in the last third of the 19th centur ...
, which are forms of reasoning that are not purely deductive, but include
material inference In logic, inference is the process of deriving logical conclusions from premises known or assumed to be true. In checking a logical inference for formal and material validity, the meaning of only its logical vocabulary and of both its logical an ...
. Similarly, it is important to distinguish deductive validity and inductive validity (called "strength"). An inference is deductively valid
if and only if In logic and related fields such as mathematics and philosophy, "if and only if" (shortened as "iff") is a biconditional logical connective between statements, where either both statements are true or both are false. The connective is bi ...
there is no possible situation in which all the premises are true but the conclusion false. An inference is inductively strong if and only if its premises give some degree of probability to its conclusion. The notion of deductive validity can be rigorously stated for systems of formal logic in terms of the well-understood notions of
semantics Semantics (from grc, σημαντικός ''sēmantikós'', "significant") is the study of reference, meaning, or truth. The term can be used to refer to subfields of several distinct disciplines, including philosophy, linguistics and compu ...
. Inductive validity, on the other hand, requires us to define a reliable generalization of some set of observations. The task of providing this definition may be approached in various ways, some less formal than others; some of these definitions may use logical association
rule induction Rule induction is an area of machine learning in which formal rules are extracted from a set of observations. The rules extracted may represent a full scientific model of the data, or merely represent local patterns in the data. Data mining i ...
, while others may use
mathematical model A mathematical model is a description of a system using mathematical concepts and language. The process of developing a mathematical model is termed mathematical modeling. Mathematical models are used in the natural sciences (such as physics, ...
s of probability such as
decision tree A decision tree is a decision support tool that uses a tree-like model of decisions and their possible consequences, including chance event outcomes, resource costs, and utility. It is one way to display an algorithm that only contains co ...
s. For the most part this discussion of logic deals only with deductive logic. Abductive reasoning is a form of
inference Inferences are steps in reasoning, moving from premises to logical consequences; etymologically, the word '' infer'' means to "carry forward". Inference is theoretically traditionally divided into deduction and induction, a distinction that ...
which goes from an observation to a
theory A theory is a rational type of abstract thinking about a phenomenon, or the results of such thinking. The process of contemplative and rational thinking is often associated with such processes as observational study or research. Theories may ...
which accounts for the observation, ideally seeking to find the simplest and most likely explanation. In abductive reasoning, unlike in deductive reasoning, the premises do not guarantee the conclusion. One can understand abductive reasoning as "inference to the best explanation".


Critical thinking

Critical thinking, also called critical analysis, is clear, rational thinking involving
critique Critique is a method of disciplined, systematic study of a written or oral discourse. Although critique is commonly understood as fault finding and negative judgment, Rodolphe Gasché (2007''The honor of thinking: critique, theory, philosophy' ...
.


Dialectic

Dialectic Dialectic ( grc-gre, διαλεκτική, ''dialektikḗ''; related to dialogue; german: Dialektik), also known as the dialectical method, is a discourse between two or more people holding different points of view about a subject but wishing to ...
is a discourse between two or more people holding different points of view about a subject but wishing to establish the truth through reasoned arguments. It has been the object of study since ancient times, but only recently has it been the subject of attempts at formalisation.


Illogical thinking and irrational processes

Illogicality As the study of argument is of clear importance to the reasons that we hold things to be true, logic is of essential importance to rationality. Arguments may be logical if they are "conducted or assessed according to strict principles of validity", ...
in terms of thinking processes are, as defined by researchers such as Aaron T. Beck, cognitive distortions that cause abnormal functioning. The state of depression often feeds off of illogical thinking and results in victims being mired in self-defeating conclusions. Patients seeking psychological help may suffer from problems of over-generalization, becoming mired in general, negative conclusions on the basis of essentially insignificant life events.
Cognitive behavioral therapy Cognitive behavioral therapy (CBT) is a psycho-social intervention that aims to reduce symptoms of various mental health conditions, primarily depression and anxiety disorders. CBT focuses on challenging and changing cognitive distortions (su ...
can assist individuals in recognizing their own habits of faulty logic and slanted interpretations of past experiences. On the other hand, depression in the sense of "Weltschmerz" in its non-aesthetically realistic and non-positivistic nature is intrinsically logical and rational. Some philosophers assert that the question of value of life has not been answered in psychologically pleasing way without embracing circular reasoning fallacy. In the socio-political context, the ability to amalgamate disparate, conflicting interests and passions into an illogical synthesis has been labeled as a possible strength, albeit one with concurrent weaknesses, by literary publications such as ''
Blackwood's Magazine ''Blackwood's Magazine'' was a British magazine and miscellany printed between 1817 and 1980. It was founded by the publisher William Blackwood and was originally called the ''Edinburgh Monthly Magazine''. The first number appeared in April 18 ...
'':


See also

* Alogia * Dysrationalia


References

{{Reflist


Bibliography

*Robert Hanna, 2009. Rationality and Logic. MIT Press. Logic Reasoning