Candidate Move - Chess Glossary
Candidate Move
Definition
A candidate move is any plausible move that a player consciously selects for deeper analysis during the thinking process. Instead of trying to calculate every legal move—an impossible task except in simple positions—strong players first generate a short list of promising possibilities, known collectively as their candidate moves, and then evaluate each one in turn.
Origin & Historical Context
The term gained wide currency through the writings of Soviet grandmasters, especially Alexander Kotov in his influential 1958 book Think Like a Grandmaster. Kotov described the now-famous “tree of analysis,” arguing that failure to fix a set of candidate moves leads to mental drift and missed tactics. Modern engines use a similar principle, pruning the “search tree” to look only at the most promising branches first (alpha-beta pruning).
Why Candidate Moves Matter Strategically
- Efficiency: Reduces calculation time by focusing on critical moves.
- Error Prevention: Ensures forcing moves (checks, captures, threats) are not overlooked.
- Planning: Helps convert vague positional ideas into concrete, calculable lines.
- Psychology: Trains disciplined thinking—strong players rarely “impulse-move.”
Typical Categories of Candidate Moves
- Checks (e.g., 1…Qh4+)
- Captures (e.g., 1…Bxe4)
- Threat-creating moves (e.g., 1…Nd4 hitting the queen and c2)
- Positional improvements (doubling rooks, seizing an open file)
- Pawns breaks (e.g., f2–f4, c6–c5)
How to Identify Candidate Moves
Grandmasters often follow a mental checklist:
- Scan forcing moves first— checks, captures, discovered threats.
- Match moves to strategic goals— open a file, exchange a bad piece, exploit a weakness.
- Limit the list to 2-5 moves. More can be overwhelming; fewer risks missing resources.
- Order them logically (most forcing first) before calculating.
Illustrative Master Example
Position after 18…c5 in Fischer – Byrne, “Game of the Century,” New York 1956 (White to move):
Fischer’s candidate moves included 19. e5, 19. exd5 and the brilliant 19. Bxh7+. After calculating deeply, he chose 19. Bxh7+, initiating a celebrated king hunt that earned the game its nickname. The move would be easy to overlook without a disciplined candidate-move search starting with checks.
Common Pitfalls
- “Hope chess:” Choosing one attractive move and calculating it alone.
- Over-expanding the list: Spending valuable time on clearly inferior ideas.
- Fixation: Sticking with the initial set of candidates even when new tactical features appear.
Interesting Facts & Anecdotes
- In his own notebooks, Mikhail Tal often wrote only two letters: “C.M.” followed by a list of moves—proof that even the “Magician of Riga” relied on candidate discipline.
- When Kasparov vs. Deep Blue, 1997 was analyzed post-match, engineers noted that the machine’s top four candidate moves were evaluated up to thirty plies deep—illustrating a computer’s literal approach to the concept.
- The phrase “Don’t add a move to the list while you are calculating” is sometimes called “Kotov’s Rule,” a mnemonic used by coaches worldwide.
Practical Exercise
Set up the following FEN: 2r2rk1/pp3pp1/3qb2p/3pN3/3Pn3/2N1P3/PP2BPPP/2RQ1RK1 w - - 0 1.
It is White to move. Write down all your candidate moves before you calculate anything; then analyze each line.
Hint: Checks, captures, and the tactical idea of 1. Nxe4 are critical.
Take-aways
- The concept of candidate moves bridges raw calculation and strategic planning.
- Limiting and ordering the list is just as important as finding the moves themselves.
- Whether you are a grandmaster, club player, or silicon monster, success in chess hinges on choosing the right candidates to investigate.