text: **Deviant**
  
  Deviant logics are logical systems that reject some of the basic intuitions of classical logic. Because of 
  this, they are usually seen not as its supplements but as its rivals. Deviant logical systems differ from each 
  other either because they reject different classical intuitions or because they propose different alternatives 
  to the same issue.[134] 
  
  Intuitionistic logic is a restricted version of classical logic.[135] It uses the same symbols but excludes 
  some rules of inference. For example, according to the law of double negation elimination, if a sentence 
  . This is a valid rule of inference in 
  is not not true, then it is true. This means that 
  classical logic but it is invalid in intuitionistic logic. Another classical principle not part of intuitionistic 
  logic is the law of excluded middle. It states that for every sentence, either it or its negation is true. This 
   is true.[135] These deviations from classical logic are 
  means that every proposition of the form 
  based on the idea that truth is established by verification using a proof. Intuitionistic logic is especially 
  prominent in the field of constructive mathematics, which emphasizes the need to find or construct a 
  specific example to prove its existence.[136] 
  
   follows from 