Logic
<p><b>Logic</b> (from the <a href="https://en.wikipedia.org/wiki/Ancient_Greek" title="Ancient Greek">Ancient Greek</a>: <a href="https://en.wiktionary.org/wiki/%CE%BB%CE%BF%CE%B3%CE%B9%CE%BA%CE%AE" class="extiw" title="wikt:λογική">λογική</a>, <i>logike</i>)<a href="https://en.wikipedia.org/wiki/Logic#cite_note-argumentative-1"><sup id="cite_ref-argumentative_1-0" class="reference">[1]</sup></a> originally meaning <i>the word</i>, or <i>what is spoken</i>, (but coming to mean <i>thought</i> or <i>reason</i>) is generally held to consist of the systematic study of the form of <a href="https://en.wikipedia.org/wiki/Argument" title="Argument">arguments</a>. A valid argument is one where there is a specific relation of logical support between the assumptions of the argument and its conclusion. (In ordinary discourse, the conclusion of such an argument may be signified by words like 'therefore', 'hence', 'ergo' and so on.)
There is no universal agreement as to the exact scope and subject matter of logic (see <a href="https://en.wikipedia.org/wiki/Logic#Rival_conceptions_of_logic">§ Rival conceptions of logic</a>, below), but it has traditionally included the classification of arguments, the systematic exposition of the 'logical form' common to all valid arguments, the study of <a href="https://en.wikipedia.org/wiki/Inference" title="Inference">inference</a>, including <a href="https://en.wikipedia.org/wiki/Fallacies" class="mw-redirect" title="Fallacies">fallacies</a>, and the study of <a href="https://en.wikipedia.org/wiki/Semantics" title="Semantics">semantics</a>, including <a href="https://en.wikipedia.org/wiki/Paradox" title="Paradox">paradoxes</a>. Historically, logic has been studied in <a href="https://en.wikipedia.org/wiki/Philosophy" title="Philosophy">philosophy</a> (since ancient times) and <a href="https://en.wikipedia.org/wiki/Mathematics" title="Mathematics">mathematics</a> (since the mid-1800s), and recently logic has been studied in <a href="https://en.wikipedia.org/wiki/Computer_science" title="Computer science">computer science</a>, <a href="https://en.wikipedia.org/wiki/Linguistics" title="Linguistics">linguistics</a>, <a href="https://en.wikipedia.org/wiki/Psychology" title="Psychology">psychology</a>, and other fields.</p>