Very complicated chess question. I'm stunned.

Play what the position allows for you to play. Maxims and rules of thumb are only vaguely helpful, whereas concrete analysis keeps you in sync with what opportunities actually exist in each moment. just my 2 cents as a total patzer

This is excellent, excellent advice.

For players 2000+

But for mere mortals like you or I, we are better off sticking to attack. 

Attack is what we know. It is what we are good at.

Okay, we may be competent enough to stave off one attack, And true, some of us may play more passively and technically than others. But we do not play entire games of defense. 

Not well, anyway.

We do not have the confidence or the skills to set up and maintain an impregnable position, allow our opponent all the time and Initiative she likes, look her in the eye, and say "Do your worst." 

Not like the Masters of Defense we see, like Karpov or Karjakin do it.

Because to be a successful defender, you need to know if your position is breech-able, or not. And to do that,  you need to be able to see everything your opponent can play.

And that concept remains foreign to us. We are better off learning Ancient Greek.

I've slept on this problem and have been having a think. Maybe Boris Gulko recommends not playing "active" when in a worse position as long as the move you play instead of an active move is a "useful" defensive move, for example in the game he recommend Ne8 and said it's generally better not to play active and Ne8 defends d6, if the knight defends d6 that means it's at least performing a useful function.

Have you ever had those game where you were just better than your opponent the entire game, much more active and even thought you were winning but it just never came to fruition?

Maybe they happened to play defensive "useful" moves rather than active or passive moves.

This is my theory on the statement so far but as I say I might be able to ask a GM next week.

Think of it this way. When you are 3-0 down in football with 10 mins to go, you hold you accept you have lost and you buckle down and make it hard for your opponents to score more. You dont at that point start throwing everyone forward and compound your defeat.

Similarly in chess when you are in a lost position keep things closed make your opponenet work for the win and don't make it easy for him to find open lines to your king.

I guess that is what he is trying to say.

I strongly disagree, sorry.

Being 3-0 down in a football match is very different from being even on material in a slightly worse position in a chess game.

I see it like this: for any player (and especially for an amateur) psychologically it's much easier to play actively than passively. And by passive play I mean patient maneuvering. It's not easy to play a move like Ne8. So we should be aware of this inherent bias and evaluate moves objectively even if this passive line looks annoying at first.

Two examples from my OTB games. In 1st I got a slightly inferior knight endgame against a higher rated player. Instead of patient maneuvering I started playing "actively" - pushing pawns, offering exchanges... and lost quickly. In 2nd game I misplayed the opening and got really cramped and unpleasant position. I was limited to rather passive play just trying to answer the immediate threats. And somehow my opponent (some 150 points above me) got overconfident and started making mistakes one after another. After a long struggle I could win that game.

1. c4 e6 2. Nf3 c5 3. g3 Nf6 4. Bg2 d5 5. O-O Nc6 6. d4 Be7 7. dxc5 Bxc5 8. a3 a6 9. b4 Ba7 10. Bb2 O-O 11. Nbd2 Qe7 12. Qc2 Rd8 13. e4 dxe4 14. Nxe4 e5 15. Rad1 Bg4 16. c5 Nxe4

f

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1. it is good
2. 100 out of 100

yup. he is spot on mate.

there are endgame or late middle game fortresses where you can just try to defend when you are at some disadvantage (rating, material, black...etc). But, in a normal middle game situation or even normal end game situations, it's better to be active than passive. Counter play... 

Ok so I spoke with an FM and a GM, here is the general jist of what they said: 

FM: depends on the position.

GM: depends on the position although if you try to attack from a weaker state it could make things worse.

Personally, I like the "muddy the waters" comment.  May not playing "actively" is related to rule of "exchange Pawns not Pieces when you're behind."

When I'm behind, muddying the waters is what I try to do.

Here's a game where I blundered and dropped a Rook.  I knew my only chance to win was to aim every piece I had at my opponent's King and attack - while trying to keep as many of my Pieces on the board as was practical. I was very active here, but note in the commentary where a couple times Stockfish preferred an exchanging move that would have been better in terms of Pawn Equivalents but would have been stupid in terms of trying to win the game - maybe that's what Gulko meant about not being "active." This is one of my favorite games: