Here's a case of a well-thought-out rule. Since nobody can produce a checkmate even if both players cooperate in the demise of one, the game is automatically called a draw.

Easy Cases

The simplest case is king against king. Next simplest is king and minor piece against king. These situations are automatic, because the players could play moves until the cows come home and nobody could ever produce a checkmate. Notice that positions with pawns do not qualify. Pawns can promote, as you will learn in Chapter 5, so there is always sufficient mating material as long as a single pawn is on the board.

Not So Easy

When we get to king and minor piece against king and minor piece, however, we start getting into some trouble. A king and knight cannot checkmate another king and knight, and a king and bishop cannot checkmate another king with a same-colored bishop. But a king and bishop can checkmate a king and knight or a king with an opposite-colored bishop. And a king and knight can checkmate a king and bishop.

All these positions are rather obscure, however. Although checkmates are possible in such positions, they cannot be forced. These checkmates require a cooperative opponent. So for all practical purposes, all such positions are generally abandoned as drawn.

A king and two knights cannot force a lone king into submission. Incredible but true. It takes a rook or queen or two bishops or a bishop and a knight to force a checkmate on a lone king. Or a lonely pawn, who can promote into a rook or queen and thus create enough checkmating material.