In chess, it is against the rules to move into check, or to not move out of check. But why? Obviously, if you went against this rule, you'd immediately lose. But it seems strange to make it illegal to lose in such a way.

Is there a reason for this rule? Is there a reason that chess ends with checkmate rather than capturing the king?

  • 3
    Chess is such an abstract game with such a long history that I don't think it's possible to find clear reasons for individual rules. But I'm happy that the rule is like this, because otherwise stalemate wouldn't exist, and then many endgames would be way less rich than they are. – RemcoGerlich May 5 '13 at 10:03

It is basically just a shortcut that cuts the game short by one move once the outcome is obvious. According to Wikipedia, "In early Sanskrit chess (c. 500–700) the king could be captured and this ended the game. The Persians (c. 700–800) introduced the idea of warning that the king was under attack (announcing check in modern terminology). This was done to avoid the early and accidental end of a game. Later the Persians added the additional rule that a king could not be moved into check or left in check. As a result, the king could not be captured."

The one difference from "real chess" that it does cause is actually rather significant. In a normal game of chess, stalemate is declared a draw, as Black has no legal move. For example:

[title "Black to move"]
[FEN "4k3/4P3/4K3/8/8/8/8/8 w - - 0 1"]

If moving into check were allowed and capturing the king ended the game, Black could move his king in this situation and White would capture it, winning the game. Opinions vary, even among grandmasters, whether stalemate is a good rule for chess or not, but in any case it is a consequence of the check rules, and a large fraction of draws are the result of it. Once again Wikipedia has a good summary of the consequences for endgame theory of abolishing the stalemate rule and making capturing the king the requirement to win the game.

  • 6
    Stalemate allows for some dazzling draw tactics! Of course leave it in! – ldog May 7 '13 at 10:30
  • 6
    Agreed; I personally think that the wide drawing margin of chess is a feature, not a bug. – dfan May 7 '13 at 11:37
  • 1
    Not to turn this into a conversation, but it also shows the strength of the player and/or skill, to be able to move into a draw position and avoid a checkmate. – MDMoore313 May 7 '13 at 13:43
  • 2
    "stalemate ... is declared a draw, as Black has no legal move. ... in any case [stalemate] is a consequence of the check rules" It's certainly a consequence of the check rules that Black has no legal moves once stalemated, but the decision whether or not to call that situation a draw or a win for White is entirely independent of the check rules themselves. And that's played out in the actual history of the game too; there have been periods in which the current check/mate rules were in force, yet stalemate was generally considered a win for the stalemater, contra the modern-day convention. – ETD May 7 '13 at 23:01
  • 1
    Maybe .75 for the stalemate and .25 for the stalemated would be a good compromise in tournaments? – ZL1Corvette Apr 17 '15 at 14:54

Not the answer you're looking for? Browse other questions tagged or ask your own question.