The reason is the capacity of consciously making sense of things, judgments, applying logic, and adapting or justifying practices, institutions, and beliefs based on new or existing information. It is closely associated with such characteristically human activities as philosophy, science, language, mathematics, and art, and is normally considered to be a distinguishing ability possessed by humans.

The reasoning is a process of thinking during which the individual is aware of a problem identifies, evaluates, and decides upon a solution; it is associated with thinking, cognition, and intellect. The field of logic studies ways in which humans reason formally through argument.

Etymology and related words

In the English language and other modern European languages, “reason”, and related words, represent words which have always been used to translate Latin and classical Greek terms in the sense of their philosophical usage.

  • “Reason” comes from the Latin word ratio, a term that in common parlance meant calculation or ratio. It was Cicero who used it to translate the word logos, which, however, in Greek also assumes the additional meaning of speech.
  • The original Greek term was “λόγος” logos, the root of the modern English word “logic” but also a word which could mean for example “speech” or “explanation” or an “account” (of money handled).
  • In the Middle Ages, scholasticism instead used the term ratio to translate the Greek dianoia, which is that faculty opposed to nous that is translated into Latin as intellectus.
  • As a philosophical term logos was translated in its non-linguistic senses in Latin as ratio. This was originally not just a translation used for philosophy, but was also commonly a translation for logos in the sense of an account of money.
  • French raison is derived directly from Latin, and this is the direct source of the English word “reason”.

The earliest major philosophers to publish in English, such as Francis Bacon, Thomas Hobbes, and John Locke also routinely wrote in Latin and French, and compared their terms to Greek, treating the words “logos“, “ratio“, “raison” and “reason” as interchangeable. The meaning of the word “reason” in senses such as “human reason” also overlaps to a large extent with “rationality” and the adjective of “reason” in philosophical contexts is normally “rational”, rather than “reasoned” or “reasonable”. Some philosophers, Thomas Hobbesfor example, also used the word ratiocination as a synonym for “reasoning”.


Reason, in philosophy, is the faculty of the intellect by means of which rational thought is exercised, that is, the one directed to abstract arguments typical of reasoning, as opposed to the sphere of irrationality. Function of human thought whose activity establishes the necessary and universal connections between concepts, realizing a mediated and progressive knowledge, able to offer man an instrument of understanding of reality and guidance of conduct. This concept is referred to the thinkers of classical antiquity, Greek and Latin, who generally distinguish, in the context of thought, the function properly rational from the intuitive. In a second meaning, again in classical thought, reason is understood as the metaphysical principle of universal order. This conception can be seen in Stoic and Neoplatonic thought.

Medieval Christian Scholasticism takes up the classical concept of discursive reason, distinguishing it from the intellect, still understood as the organ of intuitive knowledge. The power of reason, however, is subordinated to faith, considered the only true source of truth. Renaissance thought, on the other hand, asserts the autonomy of reason as an instrument for formalizing experience and as the foundation of true knowledge: scientific knowledge (Leonardo, Galileo).

In the modern age (XVII-XVIII centuries) two interpretations of the concept of reason prevail: the rationalist one that tends to affirm the self-foundation of reason on itself and the empiricist one that recognizes instead as the foundation of reason the experience. The problem of the foundation of reason was explicitly addressed in a critical way by I. Kant at the end of the eighteenth century. He distinguishes in the activity of reason an a priori and universal component (the forms or categories) and an a posteriori component (the data of experience).

On the combination of the two components is based the dual character of rational knowledge: empirical and universal. Nineteenth-century idealistic romanticism insisted instead on the aprioristic and foundational character of reason, which, however, is given a real ontological status and not only formal. This leads to the well-known formulation of Hegel: “What is rational is real, what is real is rational”, which expresses the identity between reality and reason. To the ontological rationalism of idealism are opposed the conceptions of reason expressed by contemporary thought: the pure rationalism of logical neoempiricism considers reasoning as a formal deductive and tautological system.

From phenomenology, reason is seen as the place where the essences of real objects manifest themselves. Similarly, American neorealism (Santayana, Whitehead) distinguishes reason as an organ of knowledge of essences or permanent and universal forms from “animal faith” which is knowledge of the sensitive, material. On the provisionality of the knowledge of reason insists instead Whitehead. In a less theoretical perspective, reason, for pragmatism, is a function that is operationally realized in the transformation and improvement of the environment.

Finally, the latest forms of positive existentialism consider reason as the instrument that man has to manage his own freedom, identifying for it possible spaces of intervention and realization. § Average and extreme reason, in knowledge is the relationship that reason establishes between the concepts considered, so that having realized that the first derives from the second, it does not need to dwell on the average one, but goes straight to the extreme. Spinoza gives this explanation: in a numerical progression when we suddenly see the relationship between the first number and the second we can go immediately to the last without dwelling on the intermediate one.


The notion called reason or cause (causa petendi according to the terminology of the Romanesque tradition), or even claim, responds to the need, that the study of the process feels, for a link between substantive law and process through the statements of the party who, taking the initiative of the judgment, aspires to be right. Therefore, the reason is essentially intended to recall and represent in the process the legal situation at issue according to the unilateral appreciation of the party that takes the initiative of the judgment. The reason relied on by the latter is nothing more than a unilateral and disputable presentation of the existing situation; and whether or not it is based on facts cannot be established while the trial is pending. It follows that, in the field of procedural law, it can and must be spoken of as a reason relied on, even if, upon investigation by the judge, it appears not to correspond to the real situation of law, that is, wholly or partially unfounded.

Company name: the name of a company, that is the sign with which it distinguishes itself and differs from similar companies with which it has relations. It consists of the name of one or more partners with the indication of the corporate relationship. We speak of company name for general and limited partnerships. For the joint stock company, limited partnership and limited liability company, the law speaks of company name.

Reason made: an expression equivalent to: doing justice to oneself, without the necessary recourse to the competent authority. It is, of course, contrary to the law, because the opposing party has no way of making his reasons heard before a neutral judge and because it is opposed to the very concept of justice, which resides as a right in the people, who delegate the exercise of it to their legitimate representatives; consequently, only the judges are the sole depositaries of the right authorized to exercise it.


Reason for exchange, ratio between imports and exports in an economic system. It can be expressed in terms of price (ratio between the price indices of the two incoming and outgoing flows) or quantity or value.

The terms of trade calculated on the basis of price indices are more widely used and significant because they “highlight how the competitive strength of exporters and importers operating respectively in the economic system in question and in the rest of the world changes over time”.

If export prices increase more than import prices, the terms of trade worsen: this means that the system concerned finds itself at a disadvantage compared to the rest of the world, having to sell more cheaply than it buys (it will naturally find itself at an advantage in the opposite case).

Logical reasoning methods and argumentation

Deductive reasoning

Deductive reasoning or deduction is the process of thinking from one or more statements (premises) to reach a logically certain conclusion (the type of logic used in hypothesis-based science); is a form of logical thinking that uses a general principle or law to forecast specific results.

In science, deduction is used to reach conclusions believed to be true. A hypothesis is formed; then evidence is collected to support it. If observations support its truth, the hypothesis is confirmed. In deductive reason, the pattern of thinking moves in the opposite direction as compared to inductive reasoning. From those general principles, a scientist can extrapolate and predict the specific results that would be valid as long as the general principles are correct.

Studies in climate change can illustrate this type of reasoning. For example, scientists may predict that if the climate becomes warmer in a particular region, then the distribution of plants and animals should change. These predictions have been made and tested, and many such changes have been found, such as the modification of arable areas for agriculture, with change based on temperature averages.

Both types of logical thinking are related to the two central pathways of scientific study: descriptive science and hypothesis-based science. Descriptive (or discovery) science, which is usually inductive, aims to observe, explore, and discover, while hypothesis-based science, which is typically deductive, begins with a specific question or problem and a potential answer or solution that can be tested. The boundary between these two forms of study is often blurred, and most scientific endeavors combine both approaches. The fuzzy boundary becomes apparent when thinking about how easily observation can lead to specific questions.

Inductive reasoning

Inductive reasoning (as opposed to deductive reasoning or abductive reasoning) is a method of reasoning in which the premises are viewed as supplying some evidence for the truth of the conclusion; is a form of logical thinking that uses related observations to arrive at a general conclusion.

Induction can be strong or weak. If an inductive argument is strong, the truth of the premise would mean the conclusion is likely. If an inductive argument is weak, the logic connecting the premise and conclusion is incorrect. While the outcome of a deductive argument is satisfied, the truth of the end of an inductive argument may be probable, based upon the evidence given. There are several key types of inductive reasoning:

  • Generalized → Draws a conclusion from a generalization. For example, “All the swans I have seen are white; therefore, all swans are probably white.”
  • Statistical → Draws a conclusion based on statistics. For example, “95 percent of swans are white” (an arbitrary figure, of course); “therefore, a randomly selected swan will probably be white.”
  • Sample → Draws a conclusion about one group based on a different, sample group. For example, “There are ten swans in this pond and all are white; therefore, the swans in my neighbor’s pond are probably also white.”
  • Analogous → Draws a conclusion based on shared properties of two groups. For example, “All Aylesbury ducks are white. Swans are similar to Aylesbury ducks. Therefore, all swans are probably white.”
  • Predictive → Draws a conclusion based on a prediction made using a past sample. For example, “I visited this pond last year and all the swans were white. Therefore, when I visit again, all the swans will probably be white.”
  • Causal inference → Draws a conclusion based on a causal connection. For example, “All the swans in this pond are white. I just saw a white bird in the pond. The bird was probably a swan.”

A scientist makes observations and records them. These data can be qualitative or quantitative, and the raw data can be supplemented with drawings, pictures, photos, or videos. From many observations, the scientist can infer conclusions (inductions) based on evidence. Inductive reasoning involves formulating generalizations inferred from careful consideration and the analysis of a large amount of data.

Analogical reasoning

Analogical reasoning is a method of information processing that compares similarities between new and understood concepts, then uses those similarities to understand the new concept. It is a form of inductive reasoning because it strives to provide understanding of what is likely to be true, rather than deductively proving something as fact. This method can be used by children and adults as a way to learn new information or as part of a persuasive argument.

Analogical reasoning is fundamental to human thought and, arguably, to some nonhuman animals as well. Historically, analogical reasoning has played an important, but sometimes mysterious, role in a wide range of problem-solving contexts. The explicit use of analogical arguments, since antiquity, has been a distinctive feature of scientific, philosophical and legal reasoning.

The process of analogical reasoning begins with a person determining the target domain or new idea to be learned or explained. It is then compared to a general matching domain or idea that is already well understood. The two domains must be sufficiently similar to make a valid and substantive comparison. Specific qualities that belong to the matching domain are chosen, then related elements in the target domain are sought to tie the two domains together. For example, the effect of food on the human body may be an analogy to the effect of gasoline on a car because both are responsible for the proper functioning of the entities.

Analogical reasoning is based on the brain’s ability to form patterns by association. The brain may be able to understand new concepts more easily if they are perceived as part of a pattern. If a new concept is compared to something the brain already knows, the brain is more likely to store the new information more easily.

The study of the process and effectiveness of analogical reasoning has applications in many fields. Because analogies demonstrate the likelihood of similarities rather than actually proving them, lawyers can use analogical arguments during cases that do not have much evidence. Such an argument indicates a shared similarity between two ideas or objects, then uses that shared similarity to argue that the ideas are likely to have other things in common as well. For example, a lawyer may form an analogy between his client and a previous court case for the same crime in which the person was found not guilty. Because the circumstances of the charges are similar, a lawyer will argue that the results should also be similar.

The field of science also uses this type of reasoning, but it is used to come up with new concepts rather than persuasion. Scientists will often compare a proven scientific process with an unproven one to form hypotheses on which to base new research. They may think that because two processes are similar in one way, they are more likely to have more things in common.

Psychologists often focus on the cognitive aspects of reasoning. They may perform research to determine how and why the brain retains information through analogies. Psychologists may also study the differences between how children and adults use them.

Abductive reasoning

Abductive reasoning is a form of logical inference typically begins with an observation or an incomplete set of observations then seeks to find the simplest and most likely explanation. This process, unlike deductive reasoning, yields a plausible conclusion but does not positively verify it. Abductive conclusions are thus qualified as having a remnant of uncertainty or doubt, which is expressed in retreat terms such as “best available” or “most likely.”

One can understand the abductive reasoning as an inference to the best explanation, although not all uses of the terms abduction and inference to the best explanation are precisely equivalent.

Fallacious reasoning

Flawed reasoning in arguments is known as fallacious reasoning. Bad reasoning within arguments can be because it commits either a formal fallacy or an informal fallacy. A charge of fallacious reasoning always needs to be justified. The burden of proof is on your shoulders when you claim that someone’s reasoning is fallacious. Even if you do not explicitly give your reasons, it is your responsibility to be able to give them if challenged.

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 mere structure, of the argument.

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