In logic

Logic

In philosophy, Logic is the formal systematic study of the principles of valid inference and correct reasoning. Logic is used in most intellectual activities, but is studied primarily in the disciplines of philosophy, mathematics, semantics, and computer science...

, a maiore ad minus describes a simple and obvious inference from a claim about a stronger entity, greater quantity, or general class to one about a weaker entity, smaller quantity, or specific member of that class:

• From general to particular ("What holds for all X also holds for one particular X") (essentially a less formal version of modus ponens
  Modus ponens
  In classical logic, modus ponendo ponens or implication elimination is a valid, simple argument form. It is related to another valid form of argument, modus tollens. Both Modus Ponens and Modus Tollens can be mistakenly used when proving arguments...
  
  , the best-known form of the classical syllogism and the one embodied in "All men are mortal. ...")
• From greater to smaller ("If a door is big enough for a person two meters high, then a shorter person may also come through"; "If a canister may store ten liters of petrol, then it may also store three liters of petrol.")
• From the whole to the part ("If the law permits a testator to revoke the entirety of a bequest by destroying or altering the document expressing it, then the law also permits a testator to revoke the portion of a bequest contained in a given portion of a document by destroying or altering that portion of the document.")
• From stronger to weaker ("If one may safely use a rope to tow a truck [in the American usage], one may also use it to tow a car.")

The reverse of this argument

Argument

In philosophy and logic, an argument is an attempt to persuade someone of something, or give evidence or reasons for accepting a particular conclusion.Argument may also refer to:-Mathematics and computer science:...

 is a minore ad maius

A minore ad maius

The a minore ad maius argument denotes an inference from smaller to bigger: In a strictly formulated rule , a more general rule is contained....

. Both of these arguments fall within the class of a fortiori arguments.