Answers.Body: <p>The principle is to not bring out the queen <em>too</em> early when it can be easily attacked.  In this situation there's no easy way for black to attack the queen on d4, so it's not too early.  So instead of being a weakness, the queen in a central square is a huge strength.</p>
  <p>A very similar phenomenon happens in the following line of the Scotch game where white develops the queen early and gets a +.6 edge and 43%/21% winrate on lichess.</p>
  <pre><code> [FEN &quot;&quot;]
   1. e4 e5 2.Nf3 Nc6, 3.d4 exd4, 4. Nxd4 Nxd4 5.Qxd4
  </code></pre>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-05-13T01:21:46.917Z
Answers.Text: In the line I showed though, the queen *is* attacked immediately and we end up giving away the bishop pair just to deal with the knight. Why is it worth doing this?
Answers.UserDisplayName: James Ko
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-05-13T01:43:34.067Z
Answers.Text: I mean that at the end of the line the queen is safe.  As for losing the Bishop pair, that’s certainly a longterm weakness, but apparently the active queen, stronger center, easier development, and extra tempo compensate.
Answers.UserDisplayName: Noah Snyder
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Answers.CreationDate: 2021-05-13T00:42:09.627Z
Answers.LastActivityDate: 2021-05-13T00:42:09.627Z
Answers.UserDisplayName: Noah Snyder
Answers.Body: <p>This position also arises from the Old Steinitz variation of the Ruy Lopez.</p>
  <pre><code>[FEN &quot;&quot;]
  1. e4 e5 2. Nf3 Nc6 3. Bb5 d6 4. d4 exd4 5. Qxd4
  </code></pre>
  <p>White has achieved the Ruy dream pawn structure and a space advantage. Likely followups are either <strong>c4</strong> or <strong>Nc3</strong> then <strong>Nd5</strong>. Black may give back the bishop-pair to eliminate the strong Knight.</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-05-17T19:15:36.717Z
Answers.LastActivityDate: 2021-05-17T19:15:36.717Z
Answers.UserDisplayName: Andrew Lazarus
Answers.Body: <p>Well, why shouldn't it? It's a developping move that recaptures the pawn. &quot;Don't move your queen early&quot; is not really a &quot;principle&quot;. The correct &quot;principle&quot; would be &quot;activate your pieces better and faster than your opponent&quot;, which often involves some rules of thumb like &quot;don't move your queen early&quot; or &quot;don't move the same piece several times&quot;, but some of those &quot;derived rules&quot; are broken in almost all major openings</p>
  <p>White has a great spatial advantage, and a lead in development. His pieces have better squares to go to. A quick queenside castling followed by an e5 break could be a threat to deal with.</p>
  <p>Anyway please note that <strong>4.Qxd4</strong> scores worse than <strong>4.Nxd4</strong> (ChessTempo's database), so (IF statistics are a valid way to judge it), it's not the best move in that position but rather just another reasonable way to answer <strong>3...exd4?!</strong>. <strong>4.Bc4</strong> scores even better by the way!</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-05-13T07:06:34.210Z
Answers.Text: 4.Bc4 does not score better in the lichess masters db, in fact Black scores better than White there. And even in the lichess games database, looking at e.g. Blitz or longer, 2000 or stronger, once again Bc4 does not score better than the other two moves. There, Qxd4 does in fact score best, however, in the masters DB it is Nxd4 that scores best.
Answers.UserDisplayName: koedem
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-05-13T07:10:02.480Z
Answers.Text: I've chosen ChessTempo's database. With no filters, Bc4 is the best-scoring move. With 2200+ filters it's oddly 4.c3!?, but the sample is small
Answers.UserDisplayName: David
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Answers.CreationDate: 2021-05-13T07:11:07.723Z
Answers.Text: I see. Might be worth adding to the answer since it's not clear from context and the OP mentioned using the lichess db.
Answers.UserDisplayName: koedem
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-05-13T07:12:43.743Z
Answers.Text: @koedem Probably. I'll add it. Anyway that's not the main focus of the answer, but rather the fact that some " opening principles" don't apply to most actual positions.
Answers.UserDisplayName: David
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-05-13T06:48:14.673Z
Answers.LastActivityDate: 2021-05-15T22:23:43.110Z
Answers.LastEditDate: 2021-05-15T22:23:43.110Z
Answers.UserDisplayName: David
Body: <p>I recently learned that this is a valid way for White to play for advantage against the Philidor:</p>
  <pre><code>[FEN &quot;&quot;]
  
  1.e4 e5 2.Nf3 d6 3.d4 exd4 4.Qxd4 Nc6 5.Bb5 Bd7 6.Bxc6 Bxc6
  </code></pre>
  <p>According to the Lichess database, White has won 59% of games from this position, while Black has only won 34%. The Masters database also heavily favors White, with 31% White wins / 17% Black wins.</p>
  <p>What are the ideas behind White's 4.Qxd4 move, and why does it have such a high winrate? What is White's motivation for violating principles like bringing out his queen very early / giving up the bishop pair?</p>
  
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2021-05-13T01:43:12.583Z
Comments.Text: What is your alternative to 4.Qxd4 that doesn't violate any princples? 4.Nxd4 violates principles by moving the same piece twice in the opening.
Comments.UserDisplayName: bof
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2021-05-13T02:03:24.557Z
Comments.Text: in the final position, the queen controls so many squares in the center. And importantly, cannot easilly be kicked away, so basically it exert's it's dominant influence into the game.
Comments.UserDisplayName: CognisMantis
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2021-05-13T06:38:19.750Z
Comments.Text: @bof There is no such principle as "don't move your piece twice" that applies here, since d4 forced Black to move the same pawn twice. You shouldn't think chess in those terms.
Comments.UserDisplayName: David
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2021-05-13T20:33:17.193Z
Comments.Text: These are wavy guidelines, not principles. By involving her Queen, White is obeying higher principles like initiative, forcing captures, rapid development, more advanced pawn center, and not retreating. Computers have taught us this is the best way to play. Your position is with White to move. Compare the Kingsides! Black can barely manage to harass the Queen even if he spent several moves.
Comments.UserDisplayName: BaseZen
Tags: <opening>
Title: What are the ideas behind the 4.Qxd4 variation of Philidor's Defense?
ThreadText: # What are the ideas behind the 4.Qxd4 variation of Philidor's Defense?
  
  (Asked by: username_0 on 2021-05-13)
  
  I recently learned that this is a valid way for White to play for advantage against the Philidor:
  
  ```
  [FEN ""]
  
  1.e4 e5 2.Nf3 d6 3.d4 exd4 4.Qxd4 Nc6 5.Bb5 Bd7 6.Bxc6 Bxc6
  
  ```
  
  According to the Lichess database, White has won 59% of games from this position, while Black has only won 34%. The Masters database also heavily favors White, with 31% White wins / 17% Black wins.
  
  What are the ideas behind White's 4.Qxd4 move, and why does it have such a high winrate? What is White's motivation for violating principles like bringing out his queen very early / giving up the bishop pair?
  
  **Tags:** opening
  
  > **Comments:**
  > **username_1**: What is your alternative to 4.Qxd4 that doesn't violate any princples? 4.Nxd4 violates principles by moving the same piece twice in the opening.  
  > **username_2**: in the final position, the queen controls so many squares in the center. And importantly, cannot easilly be kicked away, so basically it exert's it's dominant influence into the game.  
  > **username_3**: @username_1 There is no such principle as "don't move your piece twice" that applies here, since d4 forced Black to move the same pawn twice. You shouldn't think chess in those terms.  
  > **username_4**: These are wavy guidelines, not principles. By involving her Queen, White is obeying higher principles like initiative, forcing captures, rapid development, more advanced pawn center, and not retreating. Computers have taught us this is the best way to play. Your position is with White to move. Compare the Kingsides! Black can barely manage to harass the Queen even if he spent several moves.  
  
  ---
  
  ## 3 answers
  
  ### Answer by username_5 on 2021-05-13. Score: 9
  
  The principle is to not bring out the queen *too* early when it can be easily attacked. In this situation there's no easy way for black to attack the queen on d4, so it's not too early. So instead of being a weakness, the queen in a central square is a huge strength.
  
  A very similar phenomenon happens in the following line of the Scotch game where white develops the queen early and gets a +.6 edge and 43%/21% winrate on lichess.
  
  ```
   [FEN ""]
   1. e4 e5 2.Nf3 Nc6, 3.d4 exd4, 4. Nxd4 Nxd4 5.Qxd4
  
  ```
  
  > **Comments:**
  > **username_0**: In the line I showed though, the queen *is* attacked immediately and we end up giving away the bishop pair just to deal with the knight. Why is it worth doing this?  
  > **username_5**: I mean that at the end of the line the queen is safe.  As for losing the Bishop pair, that’s certainly a longterm weakness, but apparently the active queen, stronger center, easier development, and extra tempo compensate.  
  
  ---
  
  ### Answer by username_6 on 2021-05-17. Score: 3
  
  This position also arises from the Old Steinitz variation of the Ruy Lopez.
  
  ```
  [FEN ""]
  1. e4 e5 2. Nf3 Nc6 3. Bb5 d6 4. d4 exd4 5. Qxd4
  
  ```
  
  White has achieved the Ruy dream pawn structure and a space advantage. Likely followups are either **c4** or **Nc3** then **Nd5**. Black may give back the bishop-pair to eliminate the strong Knight.
  
  
  ---
  
  ### Answer by username_3 on 2021-05-13. Score: 2
  
  Well, why shouldn't it? It's a developping move that recaptures the pawn. "Don't move your queen early" is not really a "principle". The correct "principle" would be "activate your pieces better and faster than your opponent", which often involves some rules of thumb like "don't move your queen early" or "don't move the same piece several times", but some of those "derived rules" are broken in almost all major openings
  
  White has a great spatial advantage, and a lead in development. His pieces have better squares to go to. A quick queenside castling followed by an e5 break could be a threat to deal with.
  
  Anyway please note that **4.Qxd4** scores worse than **4.Nxd4** (ChessTempo's database), so (IF statistics are a valid way to judge it), it's not the best move in that position but rather just another reasonable way to answer **3...exd4?!**. **4.Bc4** scores even better by the way!
  
  > **Comments:**
  > **username_7**: 4.Bc4 does not score better in the lichess masters db, in fact Black scores better than White there. And even in the lichess games database, looking at e.g. Blitz or longer, 2000 or stronger, once again Bc4 does not score better than the other two moves. There, Qxd4 does in fact score best, however, in the masters DB it is Nxd4 that scores best.  
  > **username_3**: I've chosen ChessTempo's database. With no filters, Bc4 is the best-scoring move. With 2200+ filters it's oddly 4.c3!?, but the sample is small  
  > **username_7**: I see. Might be worth adding to the answer since it's not clear from context and the OP mentioned using the lichess db.  
  > **username_3**: @username_7 Probably. I'll add it. Anyway that's not the main focus of the answer, but rather the fact that some " opening principles" don't apply to most actual positions.  
  
  ---
  
  