6 ms·

Funny enough, en passant is the only capture that takes a piece not in the destination square.

Dylan16807 2y ago
That's arguable. The motivation for the rule, and especially the name of the rule, suggest the pawn is not all the way there yet.
- CrazyStat 2y ago
  In what sense is the pawn not all the way there? It occupies the square, prevents any other piece from occupying the square, can deliver check or checkmate from the square, and can be captured on the square.
  - Dylan16807 2y ago
    In the sense that a pawn that's in the perfect position can strike while it is "passing", but if that doesn't happen then it finishes the move and it's too late, the opportunity is gone forever.
    - SamBam 2y ago
      Sure, but we don't have the same rule for a rook or bishop "passing" through a square where a pawn could strike it in passing. It's just it's own unique rule, born from a period of transition between pawns only being able to take one step and being able to take two.
      - Dylan16807 2y ago
        Though castling does take all kinds of strikes in passing into account for the king.
        SamBam 2y ago
        True. It's as if any piece could kill the king in transition. And yet other pieces can't kill that pawn in passing. Only another pawn. We shouldn't try to find too much logic.
        kevindamm 2y ago
        Clearly there's some Heisenberg uncertainty principle where the pawn occupies both the third (or sixth) and fourth (or fifth) rank, in a kind of superposition that only an opponent pawn situated in a certain position would be able to observe.
        FartyMcFarter 2y ago
        I think the logic is based on pragmatism. A different piece has a chance of capturing the pawn later, but a pawn would never be able to since it can't go backwards.
  - Someone 2y ago
    The OP refers to the fact that “en passant” is french for “in passing”, so the move sort-of refers to the idea that the pawn takes the other pawn while it is passing through the third or seventh row, as if the capture starts while the previous move still is in progress. Also, the pawn can’t deliver checkmate, can it, if it can be taken en passant? It probably is possible to construct a position where taking en passant would bring the king into check in another way, but in those cases, the en passant move isn’t possible.
    - Supermancho 2y ago
      Idioms do not have to be interpreted as literal, so I don't understand why anyone would think this. As I understand it: https://lichess.org/editor/rnbqkbnr/pp3ppp/8/3pp3/2pPP3/4K3/PPP2PPP/RNBQ1BNR_w_HAkq_-_0_1?color=white https://lichess.org/editor/rnbqkbnr/pp3ppp/8/3pp3/2pPP3/4K3/... the King is never in check, for the purposes of the game. The piece removed isn't in the destination square.
      - bongodongobob 2y ago
        It's because pawns used to be able to move only one square. En passant was created when they were allowed to move two squares, sort of pretending that it only moved one square and is why you can only do it immediately after the first pawn move, kind of where the pawn "should" be.
    - vitus 2y ago
      > Also, the pawn can’t deliver checkmate, can it, if it can be taken en passant? It probably is possible to construct a position where taking en passant would bring the king into check in another way, but in those cases, the en passant move isn’t possible. I believe I've managed to construct a situation where this is the case. The key is that the pawn that would be able to take en passant is being pinned (e.g. by a queen or rook) with the king directly behind it, such that the pawn cannot perform any captures. Then, you just need to make sure all of the squares adjacent to the king are threatened, and finally actually put the king into check via a pawn advancing two squares. Technically, the c4 pawn cannot be taken en passant (i.e. this is an illegal move) because it would expose the black king to a different check. But I think this is in the spirit of your question. Contrived game (which you should be able to import into https://www.chess.com/analysis https://www.chess.com/analysis or https://lichess.org/analysis https://lichess.org/analysis): 1. e4 d6 2. e5 Kd7 3. h4 Kc6 4. Rh3 d5 5. a4 d4 6. Raa3 Kc5 7. Rhg3 Kb4 8. Rg4 Qe8 9. Rag3 Qd8 10. Rg5 Kxa4 11. Rd3 Kb5 12. Ra3+ Kb6 13. d3 Kb5 14. Be2 Kc5 15. Bg4 Qd5 16. Rb3 Qe4+ 17. Ne2 Qxd3 18. Qxd3 Kd5 19. Rb6 a6 20. Nbc3+ Kc5 21. Na4+ Kd5 22. c4# Or, if you just want to see the end state: blob:https://www.chess.com/20486c7e-a582-41ef-9f1a-bb6fdea2ca36 https://www.chess.com/20486c7e-a582-41ef-9f1a-bb6fdea2ca36 (seems to work in Chrome, not in Firefox) (also: https://lichess.org/editor/rnb2bnr/1pp1pppp/pR6/3kP1R1/N1Pp2BP/3Q4/1P2NPP1/2B1K3_b_-_c3_0_22?color=black https://lichess.org/editor/rnb2bnr/1pp1pppp/pR6/3kP1R1/N1Pp2...)
- deleted 2y ago
  [deleted]
- bobmcnamara 2y ago
  That's a good way to look at it. Practically, game engines model this with an extra state variable in the tree indicating the capturable square.
Someone 2y ago
It would be fun to have a chess variant where en passant applied to every move: - you play bishop a3×e7 taking my queen - I reply with bishop a7×c5, taking your bishop en passant, getting my queen back (your bishop got taken before it reached my queen) - you reply with knight a4×b6, taking my bishop while it’s on route to intercept your bishop that took my queen. You get back your bishop, it does end up on e7, and I do lose my queen again - I reply, taking your knight while it moves through a5. Your bishop dies again, I get back my queen. - etc. For knight’s moves, I think you’d have to either make a hard rule as to what square they move over, or let the player say how they moved on every move. Also, two pieces could be taken in one move (a piece on the target square and the knight that just hopped over it) Standard chess already has some of this in the rules for castling. There, you aren’t allowed to move your king through a position where it would be attacked by an enemy piece. That’s like saying it can be taken en passant.
- jerf 2y ago
  https://www.chessvariants.org/difftaking.dir/enpassant.html https://www.chessvariants.org/difftaking.dir/enpassant.html From: https://www.chessvariants.org/alphabet.html https://www.chessvariants.org/alphabet.html Standard Wiki/TVTropes-esque warning applies.
- thaumasiotes 2y ago
  > I reply, taking your knight while it moves through a5 Knights don't move through intermediate spaces. They are unlike every other chess piece in that regard.

That's arguable. The motivation for the rule, and especially the name of the rule, suggest the pawn is not all the way there yet.

CrazyStat 2y ago
In what sense is the pawn not all the way there? It occupies the square, prevents any other piece from occupying the square, can deliver check or checkmate from the square, and can be captured on the square.
- Dylan16807 2y ago
  In the sense that a pawn that's in the perfect position can strike while it is "passing", but if that doesn't happen then it finishes the move and it's too late, the opportunity is gone forever.
  - SamBam 2y ago
    Sure, but we don't have the same rule for a rook or bishop "passing" through a square where a pawn could strike it in passing. It's just it's own unique rule, born from a period of transition between pawns only being able to take one step and being able to take two.
    - Dylan16807 2y ago
      Though castling does take all kinds of strikes in passing into account for the king.
      - SamBam 2y ago
        True. It's as if any piece could kill the king in transition. And yet other pieces can't kill that pawn in passing. Only another pawn. We shouldn't try to find too much logic.
        kevindamm 2y ago
        Clearly there's some Heisenberg uncertainty principle where the pawn occupies both the third (or sixth) and fourth (or fifth) rank, in a kind of superposition that only an opponent pawn situated in a certain position would be able to observe.
        FartyMcFarter 2y ago
        I think the logic is based on pragmatism. A different piece has a chance of capturing the pawn later, but a pawn would never be able to since it can't go backwards.
- Someone 2y ago
  The OP refers to the fact that “en passant” is french for “in passing”, so the move sort-of refers to the idea that the pawn takes the other pawn while it is passing through the third or seventh row, as if the capture starts while the previous move still is in progress. Also, the pawn can’t deliver checkmate, can it, if it can be taken en passant? It probably is possible to construct a position where taking en passant would bring the king into check in another way, but in those cases, the en passant move isn’t possible.
  - Supermancho 2y ago
    Idioms do not have to be interpreted as literal, so I don't understand why anyone would think this. As I understand it: https://lichess.org/editor/rnbqkbnr/pp3ppp/8/3pp3/2pPP3/4K3/PPP2PPP/RNBQ1BNR_w_HAkq_-_0_1?color=white https://lichess.org/editor/rnbqkbnr/pp3ppp/8/3pp3/2pPP3/4K3/... the King is never in check, for the purposes of the game. The piece removed isn't in the destination square.
    - bongodongobob 2y ago
      It's because pawns used to be able to move only one square. En passant was created when they were allowed to move two squares, sort of pretending that it only moved one square and is why you can only do it immediately after the first pawn move, kind of where the pawn "should" be.
  - vitus 2y ago
    > Also, the pawn can’t deliver checkmate, can it, if it can be taken en passant? It probably is possible to construct a position where taking en passant would bring the king into check in another way, but in those cases, the en passant move isn’t possible. I believe I've managed to construct a situation where this is the case. The key is that the pawn that would be able to take en passant is being pinned (e.g. by a queen or rook) with the king directly behind it, such that the pawn cannot perform any captures. Then, you just need to make sure all of the squares adjacent to the king are threatened, and finally actually put the king into check via a pawn advancing two squares. Technically, the c4 pawn cannot be taken en passant (i.e. this is an illegal move) because it would expose the black king to a different check. But I think this is in the spirit of your question. Contrived game (which you should be able to import into https://www.chess.com/analysis https://www.chess.com/analysis or https://lichess.org/analysis https://lichess.org/analysis): 1. e4 d6 2. e5 Kd7 3. h4 Kc6 4. Rh3 d5 5. a4 d4 6. Raa3 Kc5 7. Rhg3 Kb4 8. Rg4 Qe8 9. Rag3 Qd8 10. Rg5 Kxa4 11. Rd3 Kb5 12. Ra3+ Kb6 13. d3 Kb5 14. Be2 Kc5 15. Bg4 Qd5 16. Rb3 Qe4+ 17. Ne2 Qxd3 18. Qxd3 Kd5 19. Rb6 a6 20. Nbc3+ Kc5 21. Na4+ Kd5 22. c4# Or, if you just want to see the end state: blob:https://www.chess.com/20486c7e-a582-41ef-9f1a-bb6fdea2ca36 https://www.chess.com/20486c7e-a582-41ef-9f1a-bb6fdea2ca36 (seems to work in Chrome, not in Firefox) (also: https://lichess.org/editor/rnb2bnr/1pp1pppp/pR6/3kP1R1/N1Pp2BP/3Q4/1P2NPP1/2B1K3_b_-_c3_0_22?color=black https://lichess.org/editor/rnb2bnr/1pp1pppp/pR6/3kP1R1/N1Pp2...)
deleted 2y ago
[deleted]
bobmcnamara 2y ago
That's a good way to look at it. Practically, game engines model this with an extra state variable in the tree indicating the capturable square.

Someone 2y ago

It would be fun to have a chess variant where en passant applied to every move: - you play bishop a3×e7 taking my queen - I reply with bishop a7×c5, taking your bishop en passant, getting my queen back (your bishop got taken before it reached my queen) - you reply with knight a4×b6, taking my bishop while it’s on route to intercept your bishop that took my queen. You get back your bishop, it does end up on e7, and I do lose my queen again - I reply, taking your knight while it moves through a5. Your bishop dies again, I get back my queen. - etc. For knight’s moves, I think you’d have to either make a hard rule as to what square they move over, or let the player say how they moved on every move. Also, two pieces could be taken in one move (a piece on the target square and the knight that just hopped over it) Standard chess already has some of this in the rules for castling. There, you aren’t allowed to move your king through a position where it would be attacked by an enemy piece. That’s like saying it can be taken en passant.

jerf 2y ago
https://www.chessvariants.org/difftaking.dir/enpassant.html https://www.chessvariants.org/difftaking.dir/enpassant.html From: https://www.chessvariants.org/alphabet.html https://www.chessvariants.org/alphabet.html Standard Wiki/TVTropes-esque warning applies.
thaumasiotes 2y ago
> I reply, taking your knight while it moves through a5 Knights don't move through intermediate spaces. They are unlike every other chess piece in that regard.