user27380: As a beginner, one quickly learns about chess principles, and in particular, opening principles.
The first openings most beginners learn are the Open Games. These were historically discovered first due to them being so logical and principled.
From the four objectively best replies to 1. e4, 1. ..e5 seems to be the most logical to me, closely followed by 1. ..c5.
..c6 theoretically and objectively speaking is on par with the aforementioned moves, but seems much less logical to me for the following (not exhaustive list of) reasons:

c6 takes less space in the center and allows White to grab the full center and a space advantage in the advance variation. In the classical mainline's pawn structure, Black doesn't even have a pawn in the center, with pawns on e6 and c6.
Instead of preparing to put a pawn in the center with c6, Black could have placed a pawn in the center immediately with e5.
to activate the bishop before closing the pawn chain, it needs to be moved several times, and then it is simply traded off by White.


..c6 does not do anything for development. Not only doesn't it open lines for the bishops, it even blocks the natural development square of the knight. c5 seems much more natural for unbalancing the pawn structure, because we achieve c5 in one move, control part of the center from the side, and do not block c6 for the knight.



So what is the reason for it being such a good opening, despite the violation of some fundamental opening principles?
If one assumes that the principles are valid (i.e. breaking them will result in some disadvantage) and that there were no good reasons c6 allows Black to get other advantages in return to compensate the disadvantage(s) resulting from the violation of principles, then there must be a refutation (i.e. White should be able to prove a sizeable advantage).

user31978: As a decent club player for fun only, I dislike facing c6 because for non-advanced book players, it often means my opponent is going to have a lot of canned responses to exploit any slight errors I make.  As to your comments about taking over the center, as you move from beginner level -- if you prefer principles over book memorization as I do, I'd suggest focusing on relative strength of knights vs bishops -- lot of good books on that which made me much stronger.  Combine that with learning to avoid holes in your pawn structure as pawns can advance but never back up, and the two edged sword of pawn moves will become more fascinating.  I recommend Pandolfini - traps and zaps to help learn patterns, his endgame and mid-game tactics were good reads as well.  While never venturing higher than expert myself, I built a chess engine who evaluated positions based on Pandolfini's techniques as much as I could and it plays at the master level and higher for blitz -- even if I turned off it's opening book.  Most clubs -- inperson, or online have some classes where they will go through advanced positions and games -- even if you're like me and not planning on memorizing all the openings, these are usually rewarding.  Happy hunting!

user30239: The Caro-Kann and for that matter the French Defense are improvements on the Scandinavian Defense. They prepare 2...d5. By preparing 2...d5 with c6 or e6, White no longer prefers to respond immediately with exd5 because now black can promote the defensive c6 or e6 pawn to d5 and Black no longer loses a tempo from 2...Qxd5.
If White plays 3.exd5 then all of the disadvantages mentioned for c6 will be removed when Black responds with cxd5. Hence, this is not White's best response.
In the main line, 1.e4 c6 2.d4 d5 3.Nc3 the center is blocked and black is fighting for control of the center. It's not clear still how White can take advantage of Black's weaknesses in this closed center. It should be noted that Fischer's main weaknesses in the opening were against the Caro-Kann and French Defenses. Fischer was a classical styled player but could never find a way to satisfactorily show how to take advantage of the weakness of either of these defenses.

user26382: 
c6 is quite good for fighting for the center: black essentially premoves d5 to challenge White's pawns. If you trade, the c-pawn becomes central. If White plays e5, the game becomes closed and all the "chess principles" give way to a completely different kind of play. (Or Black can even go for the second-main 3... c5 claiming that White's pawns are rather weak than intimidating and White himself has not done much with constant pawn moves.) Otherwise, e4 is hanging.
The bishop is moved one time: Bf5 or Bg4. If White attacks the bishop and it moves away, it's not a wasted tempo. Compare to French or Queen's gambit where the bishop is at best stupid and at worst just plain dead. Black would be happy to get rid of it at the cost of 2-3 moves.
It prepares other moves that are essential for development. If you play d5 immediately, you lose tempos after e:d5. If you play e5, White immediately gets the initiative attacking the pawn. e6, d6 block the bishops. Moreover, due to the relatively close nature of the positions arising, Black does not have to rush to develop pieces as fast as possible.

Generally, chess is a concrete game whose principles can't be reduced to a short list of rules. Still, general principles is not something Caro-Cann approach goes against, I believe: one just has to look deeper (point 3 here being an illustration).

user924: Some things I want to add to what has already been said:
You don't control the center just by placing pawns there, but by controlling center squares. The move 1...c6 does directly fight for the center: it controls d5. When black puts a pawn there next, it will be protected by another pawn.
Yes, in the typical pawn structure, black has pawns on c6 and e6. But that implies a lot of control over the central square d5, especially since white's e4 pawn doesn't control it anymore. That makes it a very solid structure, there are no real weaknesses.
Black can develop quite freely, and will aim for the pawn break ...c5 later. White's e4 pawn was already exchanged, and if his d4 pawn can be exchanged as well, what's left of that great central control by white?
It's true that 1...c6 doesn't immediately help with development. The c-pawn will have to move again, or the knight has to go to d7. But all black replies to 1.e4 have some downside, chess would be very boring if there was an opening move with only pros and no cons. That black's position is very solid will help with achieving full development, a bit later.

user13012: An opening move (really any move) can be good for one of two basic reasons.
A. It accomplishes something you want to do.
B. It prevents the opponent doing something they want to do.
Because White starts, they can to some extent do what they want, and classically this means putting Pawns in the center on e4 and d4. Black must accept that this can happen, and after 1.e4 has four different policies to counter it.

Try to do the same with  ..e5. (strategy A)

Challenge Whites center with ..d5 (strategy B)

Weaken the d4 followup with ..c5 (strategy C)

Allow the center with moves like ..d6, ..g6, ..b6 and snipe at it later (wait and see)


All four policies have proved to be viable. Assume that we have picked no. 2. Playing 1 ..d5 immediately is possible, but not everyone is happy with the loss of time involved in recovering the Pawn after 2.exd5, so more commonly the move is prepared with either ..e6 or ..c6. As you say, these moves delay development (especially ..c6), and do not directly occupy the center. What they do accomplish, as pointed out by Jonathan Rowson, is make White declare their intentions. When ..d5 comes, will White a. push, b. exchange or c. keep the tension? Black can base their future play on the choice made.
I do not think there is any strong a priori idea why this is a good idea,
but it has turned out to work. The miracle of chess is that what seems to be a set of arbitrary rules just turns out to have philosophical implications.

27380: <p>As a beginner, one quickly learns about chess principles, and in particular, opening principles.</p>
<p>The first openings most beginners learn are the Open Games. These were historically discovered first due to them being so logical and principled.</p>
<p>From the four objectively best replies to 1. e4, 1. ..e5 seems to be the most logical to me, closely followed by 1. ..c5.</p>
<p>..c6 theoretically and objectively speaking is on par with the aforementioned moves, but seems much less logical to me for the following (not exhaustive list of) reasons:</p>
<ol>
<li>c6 takes less space in the center and allows White to grab the full center and a space advantage in the advance variation. In the classical mainline's pawn structure, Black doesn't even have a pawn in the center, with pawns on e6 and c6.
Instead of preparing to put a pawn in the center with c6, Black could have placed a pawn in the center immediately with e5.</li>
<li>to activate the bishop before closing the pawn chain, it needs to be moved several times, and then it is simply traded off by White.</li>
<li>
<ol>
<li>..c6 does not do anything for development. Not only doesn't it open lines for the bishops, it even blocks the natural development square of the knight. c5 seems much more natural for unbalancing the pawn structure, because we achieve c5 in one move, control part of the center from the side, and do not block c6 for the knight.</li>
</ol>
</li>
</ol>
<p>So what is the reason for it being such a good opening, despite the violation of some fundamental opening principles?</p>
<p>If one assumes that the principles are valid (i.e. breaking them will result in some disadvantage) and that there were no good reasons c6 allows Black to get other advantages in return to compensate the disadvantage(s) resulting from the violation of principles, then there must be a refutation (i.e. White should be able to prove a sizeable advantage).</p>
 31978: <p>As a decent club player for fun only, I dislike facing c6 because for non-advanced book players, it often means my opponent is going to have a lot of canned responses to exploit any slight errors I make.  As to your comments about taking over the center, as you move from beginner level -- if you prefer principles over book memorization as I do, I'd suggest focusing on relative strength of knights vs bishops -- lot of good books on that which made me much stronger.  Combine that with learning to avoid holes in your pawn structure as pawns can advance but never back up, and the two edged sword of pawn moves will become more fascinating.  I recommend Pandolfini - traps and zaps to help learn patterns, his endgame and mid-game tactics were good reads as well.  While never venturing higher than expert myself, I built a chess engine who evaluated positions based on Pandolfini's techniques as much as I could and it plays at the master level and higher for blitz -- even if I turned off it's opening book.  Most clubs -- inperson, or online have some classes where they will go through advanced positions and games -- even if you're like me and not planning on memorizing all the openings, these are usually rewarding.  Happy hunting!</p>
 30239: <p>The Caro-Kann and for that matter the French Defense are improvements on the Scandinavian Defense. They prepare 2...d5. By preparing 2...d5 with c6 or e6, White no longer prefers to respond immediately with exd5 because now black can promote the defensive c6 or e6 pawn to d5 and Black no longer loses a tempo from 2...Qxd5.</p>
<p>If White plays 3.exd5 then all of the disadvantages mentioned for c6 will be removed when Black responds with cxd5. Hence, this is not White's best response.</p>
<p>In the main line, 1.e4 c6 2.d4 d5 3.Nc3 the center is blocked and black is fighting for control of the center. It's not clear still how White can take advantage of Black's weaknesses in this closed center. It should be noted that Fischer's main weaknesses in the opening were against the Caro-Kann and French Defenses. Fischer was a classical styled player but could never find a way to satisfactorily show how to take advantage of the weakness of either of these defenses.</p>
 26382: <ol>
<li>c6 is quite good for fighting for the center: black essentially premoves d5 to challenge White's pawns. If you trade, the c-pawn becomes central. If White plays e5, the game becomes closed and all the &quot;chess principles&quot; give way to a completely different kind of play. (Or Black can even go for the second-main 3... c5 claiming that White's pawns are rather weak than intimidating and White himself has not done much with constant pawn moves.) Otherwise, e4 is hanging.</li>
<li>The bishop is moved one time: Bf5 or Bg4. If White attacks the bishop and it moves away, it's not a wasted tempo. Compare to French or Queen's gambit where the bishop is at best stupid and at worst just plain dead. Black would be happy to get rid of it at the cost of 2-3 moves.</li>
<li>It prepares other moves that are essential for development. If you play d5 immediately, you lose tempos after e:d5. If you play e5, White immediately gets the initiative attacking the pawn. e6, d6 block the bishops. Moreover, due to the relatively close nature of the positions arising, Black does not have to rush to develop pieces as fast as possible.</li>
</ol>
<p>Generally, chess is a concrete game whose principles can't be reduced to a short list of rules. Still, general principles is not something Caro-Cann approach goes against, I believe: one just has to look deeper (point 3 here being an illustration).</p>
 924: <p>Some things I want to add to what has already been said:</p>
<p>You don't control the center just by <em>placing</em> pawns there, but by <em>controlling center squares</em>. The move 1...c6 does directly fight for the center: it controls d5. When black puts a pawn there next, it will be protected by another pawn.</p>
<p>Yes, in the typical pawn structure, black has pawns on c6 and e6. But that implies a lot of control over the central square d5, especially since white's e4 pawn doesn't control it anymore. That makes it a very solid structure, there are no real weaknesses.</p>
<p>Black can develop quite freely, and will aim for the pawn break ...c5 later. White's e4 pawn was already exchanged, and if his d4 pawn can be exchanged as well, what's left of that great central control by white?</p>
<p>It's true that 1...c6 doesn't immediately help with development. The c-pawn will have to move again, or the knight has to go to d7. But all black replies to 1.e4 have <em>some</em> downside, chess would be very boring if there was an opening move with only pros and no cons. That black's position is very solid will help with achieving full development, a bit later.</p>
 13012: <p>An opening move (really any move) can be good for one of two basic reasons.</p>
<p>A. It accomplishes something you want to do.</p>
<p>B. It prevents the opponent doing something they want to do.</p>
<p>Because White starts, they can to some extent do what they want, and classically this means putting Pawns in the center on e4 and d4. Black must accept that this can happen, and after 1.e4 has four different policies to counter it.</p>
<ol>
<li><p>Try to do the same with  ..e5. (strategy A)</p>
</li>
<li><p>Challenge Whites center with ..d5 (strategy B)</p>
</li>
<li><p>Weaken the d4 followup with ..c5 (strategy C)</p>
</li>
<li><p>Allow the center with moves like ..d6, ..g6, ..b6 and snipe at it later (wait and see)</p>
</li>
</ol>
<p>All four policies have proved to be viable. Assume that we have picked no. 2. Playing 1 ..d5 immediately is possible, but not everyone is happy with the loss of time involved in recovering the Pawn after 2.exd5, so more commonly the move is prepared with either ..e6 or ..c6. As you say, these moves delay development (especially ..c6), and do not directly occupy the center. What they do accomplish, as pointed out by Jonathan Rowson, is make White declare their intentions. When ..d5 comes, will White a. push, b. exchange or c. keep the tension? Black can base their future play on the choice made.</p>
<p>I do not think there is any strong a priori idea why this is a good idea,
but it has turned out to work. The miracle of chess is that what seems to be a set of arbitrary rules just turns out to have philosophical implications.</p>
