text: **Logic**
  
  **Logic**is the study of correct reasoning. It includes both formal and 
  informal logic. Formal logic is the study of deductively valid 
  inferences or logical truths. It examines how conclusions follow 
  from premises based on the structure of arguments alone, 
  independent of their topic and content. Informal logic is associated 
  with informal fallacies, critical thinking, and argumentation 
  theory. Informal logic examines arguments expressed in natural 
  language whereas formal logic uses formal language. When used 
  as a countable noun, the term "a logic" refers to a specific logical 
  formal system that articulates a proof system. Logic plays a 
  central role in many fields, such as philosophy, mathematics, 
  computer science, and linguistics. 
  
  Logic studies valid forms of 
  inference like*modus ponens*. 
  
  Logic studies arguments, which consist of a set of premises that leads to a conclusion. An example is the 
  argument from the premises "it's Sunday" and "if it's Sunday then I don't have to work" leading to the 
  conclusion "I don't have to work".[1] Premises and conclusions express propositions or claims that can be 
  true or false. An important feature of propositions is their internal structure. For example, complex 
  propositions are made up of simpler propositions linked by logical vocabulary like 
  (if...then). Simple propositions also have parts, like "Sunday" or "work" in the example. The truth of a 
  proposition usually depends on the meanings of all of its parts. However, this is not the case for logically 
  true propositions. They are true only because of their logical structure independent of the specific 
  meanings of the individual parts. 
  
   (and) or 