Jeff maintains that in a competitive auction, after we have found a fit, we should use double to penalize the opponents, bid with an offensive hand, and pass otherwise [I hope I have this right]. And I would guess that at least 95% of active bridge players would agree with him. I recognize that I am in the minority.
So, I'd like to explain why I think my style is better. But, first, I'd better summarize it. When we find a fit at the two-level, we usually don't know whether it's a single eight-card fit, a nine-card-plus fit or some kind of double fit. I say "usually" because pairs playing Bergen raises and perhaps some other conventions actually do know. But, I am talking about the normal situation where the auction has gone, say, 1♥ (p) 2♥ or perhaps 1♦ (p) 1♥ (p) 2♥, although for simplicity I will only discuss the first of these auctions. Let's say that the last bid is immediately overcalled by 2♠. Or perhaps there is a double, taken out to 2♠. How should we proceed?
I recommend what amounts to a pass-double inversion, just like some expert pairs play at higher levels when they're in a forcing pass situation. Here, we're not in a force, of course, but I should say that we will do something probably 75% of the time or more. Pass says either "I have neither extra strength nor extra distribution" or "I have a hand which would like to defend a doubled contract if you have extra strength." Double says "I'm relatively short in their suit [usually a doubleton], and I have extra strength but no clear bid." Much of the time, therefore, we will bid on, sometimes we will "nail" the opponents and sometimes we will meekly pass and let them have the contract.
The first thing we notice is that we no longer have a good way to invite game. All of our Kokish game tries, help-suit game tries and their like are essentially out the window. We can show a second suit, bid 2NT or we can bid 3♥ (higher bids will commit our side to game anyway). But those bids can also be used simply to compete with an offensively-oriented hand. Which style makes most sense? I believe that the scoring table favors an approach which goes: declare before game before slam. I don't have the space to justify this idea here but I do talk about it some more in Two golden rules of bidding. But very briefly: if they have intervened with 2♠, and can make it while you can take ten tricks not-vulnerable in hearts, you will earn 7 imps just by bidding on to 3♥ and only a further 4 imps by actually bidding game. If you think you might be able to make game but have no good way to find out partner's opinion, just bid it. If you're right you'll gain 11 imps, if you're wrong then at least you break even over letting them play even if they do double.
Here, I'm going to make an assumption that may shock you. Once we have established that our side has approximately half the deck (that's to say the high cards) or more, we do not need much in the way of extras to compete. It's a question of pigs at the trough—if you don't get in there you will starve. The most important issue we're faced with therefore is: declare or defend? (DoD). In other words, we are now trying to determine the absolute par contract whereas, before the intervention, we were only concerned with determining our (directional) par contract, which frequently is not the same thing. At pairs, quite a few matchpoints may be riding on whether we reach par or not. At teams, there is no difference between +100 and +110 for instance. But at matchpoints, getting it right could easily swing 25% of a board. Trying for game or trying for a big penalty are also possibilities of course, but they have to take a back seat to the main issue. So, we look at the possible tools we have available and, if there are two possible uses, we choose the meaning that most helps us to decide the DoD question. If we have sufficient tools still available to help us try for game, for example, then we use them for that purpose.
What tools do we have after the auction described above: 1♥ (p) 2♥ (2♠) ? Pass, double, 2NT, 3 of a minor, 3♥ (as mentioned above). By general agreement, pass and three of our suit (3♥ here) are non-forward going. Since defending 2♠ may be the par contract, we have to include pass in our arsenal for both players in a pair.
We are therefore left with double, 2NT, 3♦ and 3♣. I hope we all agree without any further explanation that 2NT, 3♦ and 3♣ are not logical contracts. One of these bids can be used as a game try and the other two can be used as you prefer for a different kind of game try, or simply a competitive bid. Personally, I think that the lowest of the available bids should be the game try (as it leaves the most room for partner to respond with some useful information) and the higher bids should be used to further describe your hand when you have good distribution. If RHO had bid 2NT, that would obviously remove one option... and so on until a 3♦ intervention leaves us no room for a game try at all. Let me put it on record that I do not like the "maximal double" here as an artificial game try.
Trying to penalize the opponents at this low-level is generally not going to work out profitably. If we can set their contract by two tricks doubled, that will be a very nice +300. But, wait a moment, if there are 16 total tricks available (most deals have at least this many total tricks) that means we could have made ten tricks in hearts for +420. Hence doubling for penalties won't be very profitable at equal or unfavorable vulnerability. Only at favorable vulnerability will it work out well, and even then it's only at matchpoints that the result will be a triumph. So, if we rule out wanting to penalize the opponents with a direct double, it frees up that call to show extra values and relative shortness in the enemy suit. Something like a short-suit game try. If partner has an extra trump, he will take the double out automatically. Likewise if he too is short in the enemy suit. All suit bids can be used to show extra distribution, and might even help us find that magic double fit that produces game even on minimum hands.
Thus, double is the most flexible DoD invitation. It has the advantage that if partner does decide to defend—and assuming he's right and that we don't choke during the defense—we get the greatest possible consolation for our "equity" (the score we were hoping to achieve with our two-of-a-major contract). But you mustn't abuse double here or you will end up with lots of -470s and -670s. See my various other posts in this series (DSIP). Generally, you will have a balanced hand with two cards in the opponent's suit. In this context, that means 5422, 5332, or possibly 5431 shape—not 5521 or anything like that. That's what the other suit bids are for. However, you might double your singleton (or void) suit if you've already shown two suits. And, if partner has a biddable suit in response to your double (or extra length in a suit he's already shown), he should take the double out.
So, does that mean that our opponents can enter into our auctions with impunity, safe in the knowledge that they can never be caught speeding? Not at all. Often they will escape relatively unscathed when we bid on to a successful contract or we let them play undoubled when we have nothing extra. But when the trap does close, they will find that the player with the most high-card points has the short holding in trumps. His partner will have the longer holding and these conditions are perfectly suited to extracting the largest possible penalty.
Sometimes, even when we do "catch them speeding," they can wriggle out into a better contract. So, give up on waiting for juicy doubles of low-level intervention after we've found a fit—it's better to use double as an essentially constructive tool and get the occasional penalty as a bonus.
Here's a typical layout from a recent instant tournament on BBO. At the table, all were vulnerable and West made a poor decision to reopen with double. Perhaps he should have considered the board number first. All looked good at first when East bid 2♠ and N/S passed, but things went rapidly downhill thereafter, resulting in -300, a very poor matchpoint score.
Declarer could have played it a bit better and saved a trick. Perhaps North should have redoubled over the first double to show a balanced hand with maximum points. South might then feel able to double the contract for a gain of 800 to N/S. But that's being a little greedy. N/S took no risk of anything bad happening and ended up with better than an 80% board.
Now let's look at some other variations and see how they might play out using the ideas described above. We leave the E/W hands to distribute themselves as they see fit and bid as before.
In the first example on the left, South is the one with extra strength, a balanced hand and a doubleton spade: hence double. The final contract is 2♠X for +100 (assuming an unchanged E/W layout). This loses an IMP to the par contract of +140 for 3♥.
In the second variation (right) neither North nor South can bid on over 2♠ and the opponents "escape". Nevertheless, they go down two for +200 to N/S. Surprisingly, again assuming E/W remain the same, N/S can actually make 4♥ on this layout. But is it reasonable to expect anyone to bid it? +200 is therefore likely to win at least average if not better.
And, in fairness, here's a hand that appears to deflate my arguments. It's from long ago (2006) on OKbridge (I found this using Stephen Pickett's wonderful program BridgeBrowser) where the players were all good. East/West were playing "standard" and the 500 they reaped was worth 7.35 IMPs.
Playing my recommended system, the result would almost surely be only 200 (no double) for only 0.75 IMPs. This is exactly what happened at another good table but this time, the defenders did even better and extracted 300 for 3.27 IMPs. In any case, I dare say the actions would be the same at matchpoints and there the difference is much smaller: 49/51 matchpoints for 500, 48 for 300, and 41 for 200. That's still an 80% board! In other words, you will get a very good matchpoint result on this hand without having to double.
And here's a hand which many players got seriously wrong (from the same source)—again all good players at the table shown.
Par on this board is +100 for N/S for 2♠X-1. The only reasonable way to get that result is for N/S to be playing according to my system and have South double with his extras and spade shortness. North will have no reason to take it out and par will be achieved. In practice many Easts took fewer than their allotted seven tricks and at those tables 2♠X would have done very nicely for N/S. Note that although this N/S did get a fine 300, it was only because West made a dreadful bid in my opinion. They were almost surely going to escape for -50 until then.
Now for a board where N/S use double to win the declaration:
Note that in almost every real-life playing of this hand, after the first six calls, South made a very undisciplined raise to 3♥. He has no shape and could have been summarily punished an a bad day. The safe way to show your extras is with a double as shown here. North, with four hearts and a doubleton spade will take it out to 3♥ and all will be well. If E/W bid on they will be -200 or, even worse, if N/S decide to take the push to 4♥ on their 21 hcp they will be extraordinarily lucky, given their lack of useful shape, and score game.