French Defense query

Was wondering if somebody could offer me some insight here.

I'm a relatively new playerof the French Defense and this position as Black always confuses me.

The accepted line, if you can call it that, is to advance the pawn to c5 once the Bishop has been taken on c3. Apologies for not showing that on the board.

Now, I can't fathom that move. The reason being that my instinct, as white, would be to take the pawn straight away with Black losing the advantage.

On the Game Exlporer only 1 game suggests that White could take the Blck pawn on c5. All others (nearly 2,800) suggest that White should move the Queen to g4.

My question is, why is dxc5 such an awful (or frowned upon) move? I can't see any advantage for Black whatsoever.

Thanks

Guessing white's not wild about the prospect of giving up the center and tripling his pawns all in one fell stroke.

Concretely, after Qc7, attacking both c5 and e5, white has given the pawn back and given up the center for nothing.

As black, you shouldn't consider yourself to be "down a pawn" if the capture results in your opponent creating a tripled, isolated pawn monster. In practical terms, at least one (and probably more) of those pawns will be captured by you sooner or later. They are the walking dead.

More to the point, in the Winawer French (the line you're working with), one of black's primary goals is to undermine white's center, particularly the strongpoint at e5. To this end, black will often wind up with a mutilated pawn position on his kingside following a white attack with Qg4->Qxg7.

Going back to your diagram: if white takes the "free" pawn on c5, black has achieved the goal of undermining white's center, while leaving his kingside pawns (as yet) intact. White's attack will come, but black will get in another move before it begins. To my mind, this tips the balance strongly in black's favor.