Why does castling in the Four Knights: Double Spanish opening inadvertantly stop Bxc3? So I am currently working through Chess Fundamentals by Capablanca and he said something I find opaque: following 1.e4, e5 2.Nf3, Nc6 3.Nc3, Nf6 4.Bb5, Bb4 &quot;5.0-0 an indirect way of preventing 5...Bxc3, which more experience or more study will show to be bad.&quot;
I have been trying to figure out why, if for whatever reason white does not castle (lets say 5.d3), then why is taking better for black? I looked all over for ways to exploit the king in the center, or ways to take away the white king's castling rights, but I have found nothing.
One hundred years ago grandmasters, even the great Capablanca, were given to making sweeping judgments about opening positions without supporting evidence, often condemning moves that have been shown to be quite playable. In fact 5...Bxc3 is now considered a &quot;book&quot; move, though 5...O-O is probably slightly better. And as to 5.d3 making the exchange good, after 5.d3 5...Bxc3 is now considered roughly equal to other reasonable moves like 5...O-O or 5...d6.
BTW the Four Knights Game is often casually dismissed as a &quot;drawish&quot; opening, again without supporting evidence. If you study it and try it you'll find that many opponents who expect the more usual 3.Bb5 or 3.Bc4 are unprepared for it.