Informal logic is the study of arguments as presented in ordinary language, as contrasted with the presentations of arguments in an artificial (technical) or formal language (see formal logic). The focus of informal logic lies in distinguishing good arguments (valid, cogent) from bad arguments or fallacies (invalid, uncogent). The activity of analysing argument structures in ordinary language and representing them in a diagramatic manner is normally regarded as part of informal logic. An argument is an attempt to demonstrate the truth of an assertion called a conclusion, based on the truth of a set of assertions called premises. ...
Logic (from ancient Greek λόγος (logos), meaning reason) is the study of arguments. ...
Logic (from Classical Greek Î»ÏŒÎ³Î¿Ï‚ (logos), originally meaning the word, or what is spoken, (but coming to mean thought or reason) is most often said to be the study of arguments, although the exact definition of logic is a matter of controversy amongst philosophers (see below). ...
Opinion pieces of newspapers provide illustrative textbook examples of informal logic (see the Walton reference), usually because these pieces are short and often fallacious. However, informal logic is also used to reason about events in the human and social sciences. In fact, most reasoning from known facts to unknown facts that uses natural language, even if combined with mathematical or statistical reasoning can be regarded as an application of informal logic so long as it does not rely on additional empirical evidence.
Mathematics and the natural sciences In mathematics the reasoning that occurs in proofs, though informal, is often regarded as a close approximation to a formal proof, that is one which is carried out in a formal system of logic. Note that in practice, however, the separation between an informal mathematical proof and its formal idealization is so large that hardly anyone attempts to bridge that gap. This gap arises because most steps in informal proofs accumulate an enormous number of simple logical inferences, or other proof steps which are straightforward to most readers with enough mathematical experience. Moreover, many mathematical researchers regard proof as something other than a sequence of inference steps. See platonism in mathematics. Nevertheless, one of the goals of the Mizar project is to formalize the entire body of informal proofs of mathematics. Wikibooks Wikiversity has more about this subject: School of Mathematics Wikiquote has a collection of quotations related to: Mathematics Look up Mathematics on Wiktionary, the free dictionary Wikimedia Commons has media related to: Mathematics Bogomolny, Alexander: Interactive Mathematics Miscellany and Puzzles. ...
The Mizar system consists of a language for writing strictly formalized mathematical definitions and proofs, a computer program which is able to check proofs written in this language, and a library of definitions and proved theorems which can be referred to and used in new articles. ...
In theoretical physics, arguments are used to derive new formulas or physical principles. These arguments often use mathematics, although in many cases the relations between assertions in a derivation contain mathematically serious gaps. Examples of these mathematical gaps are failure to prove convergence of an infinite series or an integral (or worse, rely on an expression whose value is known to be divergent) or ignoring quantities which are small in a limiting sense. Despite mathematical gaps, arguments used in physical derivations are generally considered to be valid arguments. Since antiquity, people have tried to understand the behavior of matter: why unsupported objects drop to the ground, why different materials have different properties, and so forth. ...
In mathematics, a series is a sum of a sequence of terms. ...
In calculus, the integral of a function is a generalization of area, mass, volume, sum, and total. ...
In mathematics, the concept of a limit is used to describe the behavior of a function, as its argument gets close to either some point, or infinity; or the behavior of a sequences elements, as their index approaches infinity. ...
Social sciences In the social sciences many arguments are based on applications of statistics to demonstrate correlation or lack thereof between sets of variables, such as levels of income and education, ethnicity and wealth and so on. Such arguments are based on theories of statistical hypothesis testing together with empirical data accumulated by polling, collection of historical records, long term studies etc. Econometrics is the branch of economics concerned with applying statistics to economics. Besides statistics, economists use a wide variety of analytical tools including Calculus, qualitative reasoning about: solutions to equations (for instance, in reasoning about supply and demand), asymptotic analysis (for example theories of growth) etc. The social sciences are a group of academic disciplines that study the human aspects of the world. ...
A statistic (singular) is the result of applying a statistical algorithm to a set of data. ...
In politics, polling is the surveying of public opinion on an issue. ...
Econometrics literally means economic measurement. It is a combination of mathematical economics, statistics, economic statistics and economic theory. ...
Law and politics An extremely intricate form of reasoning is legal reasoning since it involves such considerations as legal precedent and existing law. The nature of the propositions used in legal reasoning is one of the concerns of legal theory. Precedent is the principle in law of using the past in order to assist in current interpretation and decisionmaking. ...
This article is about law in society. ...
See also sophistry. Sophism was originally a term for the techniques taught by a highly respected group of philosophy and rhetoric teachers in ancient Greece. ...
References  David Hackett Fischer, Historian's Fallacies, New York, Harper and Row, 1970.
 Douglas N. Walton, Informal Logic. A Handbook for Critical Argumentation, cambridge University Press, 1989.
See also are you kiddin ? i was lookin for it for hours ...
A logical fallacy is an error in logical argument which is independent of the truth of the premises. ...
External links  Stanford Encyclopedia of Philosophy: informal logic
