Loki's Wager is a form of logical fallacy. It is the unreasonable insistence that a concept cannot be defined, and therefore cannot be discussed.

Loki

Loki

In Norse mythology, Loki or Loke is a god or jötunn . Loki is the son of Fárbauti and Laufey, and the brother of Helblindi and Býleistr. By the jötunn Angrboða, Loki is the father of Hel, the wolf Fenrir, and the world serpent Jörmungandr. By his wife Sigyn, Loki is the father of Nari or Narfi...

 is a trickster

Trickster

In mythology, and in the study of folklore and religion, a trickster is a god, goddess, spirit, man, woman, or anthropomorphic animal who plays tricks or otherwise disobeys normal rules and conventional behavior. It is suggested by Hansen that the term "Trickster" was probably first used in this...

 god in Norse mythology

Norse mythology

Norse mythology, a subset of Germanic mythology, is the overall term for the myths, legends and beliefs about supernatural beings of Norse pagans. It flourished prior to the Christianization of Scandinavia, during the Early Middle Ages, and passed into Nordic folklore, with some aspects surviving...

, who, legend has it, once made a bet with some dwarves. It was agreed that the price, should Loki lose the wager, would be his head. Loki lost the bet, and in due time the dwarves came to collect the head which had become rightfully theirs. Loki had no problem with giving up his head, but he insisted they had absolutely no right to take any part of his neck. Everyone concerned discussed the matter; certain parts were obviously head, and certain parts were obviously neck, but neither side could agree exactly where the one ended and the other began. As a result, Loki keeps his head indefinitely (although in the specific example, he got his lips stitched shut as payback for getting out of the bet with tricky wordplay).

The fallacy's focus on over-specification makes it in some ways the opposite of hasty generalization

Hasty generalization

Hasty generalization is a logical fallacy of faulty generalization by reaching an inductive generalization based on insufficient evidence essentially making a hasty conclusion without considering all of the variables...

 and could be considered an extreme form of equivocation

Equivocation

Equivocation is classified as both a formal and informal logical fallacy. It is the misleading use of a term with more than one meaning or sense...

.

The fallacy can be dealt with by attempting to establish a reasonable working definition of the term at play or by showing that the other party is being unreasonable and avoiding the argument.

See also

• Draupnir
  Draupnir
  In Norse mythology, Draupnir is a gold ring possessed by the god Odin with the ability to multiply itself: Every ninth night eight new rings 'drip' from Draupnir, each one of the same size and weight as the original....
  
  
• Brokkr
• No true Scotsman
  No true Scotsman
  No true Scotsman is an informal logical fallacy, an ad hoc attempt to retain an unreasoned assertion. When faced with a counterexample to a universal claim, rather than denying the counterexample or rejecting the original universal claim, this fallacy modifies the subject of the assertion to...
  
  
• The Merchant of Venice
  The Merchant of Venice
  The Merchant of Venice is a tragic comedy by William Shakespeare, believed to have been written between 1596 and 1598. Though classified as a comedy in the First Folio and sharing certain aspects with Shakespeare's other romantic comedies, the play is perhaps most remembered for its dramatic...
  
   — A similar argument over a pound of flesh erupts at the end of the play.
• Quibble
  Quibble (plot device)
  In literature, a quibble is a common plot device, used to fulfill the exact verbal conditions of an agreement in order to avoid the intended meaning. Its most common uses are in legal bargains and, in fantasy, magically enforced ones....
  
   — the use of the fallacy as a plot device.
• Vagueness
  Vagueness
  The term vagueness denotes a property of concepts . A concept is vague:* if the concept's extension is unclear;* if there are objects which one cannot say with certainty whether belong to a group of objects which are identified with this concept or which exhibit characteristics that have this...