[mikl_plkcc]

I don't understand why a pass at a high level of auction can be a forcing pass (which forces partner to either double or compete).

Imagine that both have a fit, and assume that we expect to make 4♥.

If they compete to 4♠, is a pass forcing?

If we then compete to 5♥ and they compete to 5♠, is a pass still forcing?

How do someone making a forcing pass know that the opponents aren't bidding a 50/50 contracts, where letting them play is usually a best option?

[P_Marlowe]

mikl_plkcc, on 2025-February-18, 05:10, said:

I don't understand why a pass at a high level of auction can be a forcing pass (which forces partner to either double or compete).

Imagine that both have a fit, and assume that we expect to make 4♥.

If they compete to 4♠, is a pass forcing?

If we then compete to 5♥ and they compete to 5♠, is a pass still forcing?

How do someone making a forcing pass know that the opponents aren't bidding a 50/50 contracts, where letting them play is usually a best option?

If they have bid 4S over your 4H, you can use 4NT to differentiate a 5H that (not) generates a FP situation.
You loose the option to use 4NT as RKCB, but RKCB is of less relevance if the auction is competive.

[jillybean]

mikeh, on 2023-February-09, 12:41, said:

Here’s a very useful and fairly simple plus reliable set of rules

For a FP to exist, obviously we’ve been in the auction and, almost as obviously, our side has announced some significant values

Always ask: how far have we forced ourselves?

For example, 1H (1S) 2S…..assume, as is common. It not universal, that 2S showed an invitational or better heart raise

How how have we forced ourselves?

Were opener to bid 3H, and responder had only a limit raise, clearly we are not forced…we have decided not to bid game.

Thus if the bidding goes 1H (1S) 2S (3S)……thus can’t be a FP because they’ve bid beyond the level to which we forced. Opener passes with hands on which he’d have rejected a limit raise and bids with extras.

Basic rule: if we have not established a game force, but have shown invitational or better values, we are not in a FP if the opps bid beyond our level of force…if we’re bidding a major, then we’re not forced if they bid higher than 3 of our major.

Second rule: if we’ve established a game force…which a limit or better raise does NOT do….then ALL passes are forcing no matter the level

Bear in mind that bidding game doesn’t always show values. 1S (2H) 4S (5H)

4S did, sort of, force to game. But it carried no implication of strength. Indeed, the 4S bidder often expects to fail much of the time. So for a game force to create a FP situation, it must clearly (as in partner must be able to rely upon this) be a bid based on an expectation of making…on power.



Be aware that in some auctions it’s not clear who was bidding to make. In those auctions, my advice is not to play FP.

Iow, FP arises when they are below our level of force, voluntarily set, or at any time when we’ve announced a power-based game force.

No rules are perfect.

Many years ago we had an auction in which, with a combined 25 hcp and a good heart fit, we bid 5H over 4S, and they bid 5S.

Neither of us had what we needed to think that 6H was making, and indeed it would have been one down. So we doubled, simply to honour the force. Unfortunately the hand was a bit of a freak and 5S was cold

Making matters worse, our expert teammates never bid🙁 they sold out to 4H.

Oh well.

One of the most challenging parts of bidding is to recognize that nothing is perfect, and to resist the temptation to change methods every time one gets a bad result. This problem is compounded by the difficulty of recognizing that maybe our methods are flawed….as opposed to the bad outcome being a price one should be willing to pay in order to maximize the more frequent gains from our chosen methods.

Vulnerability? Some people think vulnerability should play a role. I disagree. While the holdings of the opps, for any given auction, may vary according to vulnerability, that makes no difference to the trick making potential of our hands….and FP is all about our hands, not theirs

[DavidKok]

While everything in that mikeh quote is correct, I interpret the OP's question differently. I'll give it my own, concise, attempt:

The idea behind forcing pass is that we, as a partnership, find ourselves in a situation where we refuse to defend undoubled. In this situation, logically, if your partner passes your LHO's bid, and your RHO also passes, by partnership agreement you should not pass (ending the auction).
Normally, partner's pass would show weakness or 'nothing to contribute'. With this agreement of Forcing Pass in place though, we create more bidding sequences. This allows for assigning a different meaning to partner's pass, and lets us more accurately judge when to defend doubled, or when to bid on (and if so, how high). In other words, forcing pass trades the ability to defend undoubled for more accuracy on resulting sequences.

There are many styles of forcing pass agreements. Below I briefly give four examples, but this is not exhaustive:

• "Pass shows extras": 1♠-(P)-2NT*-(3♦), where 2NT was a Jacoby 2NT (game forcing, 4(+)♠). It makes sense here to play 4♠ as weaker than pass, and consequently, pass shows some form of extras. You can elaborate on these extras by assigning meaning to double through 4♥.
  
• "Pass is waiting, not much to say": 1♠-(P)-2♦-(2♥), where 2♦ was GF, 5(+)♦. Most people here reserve bids by opener for shapely hands, and play double as penalties. By negative inference, pass becomes a waiting bid. Arguably it is unlimited, though realistically you won't have many extras on this auction.
  
• "Pass consults partner about defending versus bidding, and shows medium ODR": 1♠-(P)-2NT*-(5♣), where 2NT was a Jacoby 2NT. Here opener doesn't have many options, and a lot of people will reserve double as an offer to defend, any 5-level bid as a really aggressive hand, and pass as 'everything else'. It is asking partner to choose between defending 5♣X, playing 5♠, and trying for slam.
  
• "Pass-double inversion": 1♠-(P)-2NT*-(5♣), where 2NT was a Jacoby 2NT. Some experts like to flip the meaning of pass and double compared to the previous example, using pass to mean 'I have a penalty double, please double on my behalf' and double to mean 'what do you think, partner?'. This allows for overloading the pass call by defining pass-then-pull (after partner's expected double on our behalf) and creates more sequences.

Notice how this agrees with mikeh's text, and how I've carefully constructed the examples based on the relative level of the interference and our force.

[akwoo]

mikl_plkcc, on 2025-February-18, 05:10, said:

How do someone making a forcing pass know that the opponents aren't bidding a 50/50 contracts, where letting them play is usually a best option?

If you were omniscient, letting them play undoubled would never be the best option. Either they go down, in which case you should have doubled, or they make, in which case you should have bid on, since even if you go down it's less than their score for making.

Now, given that you aren't omniscient, it's good to give yourselves a little bit of slack, but on hands where making a mistake on this isn't likely to be too costly (because there's a good chance that they'll go down AND you'll make if you bid on), you should always be picking one or the other.

Hence, if you should never let them play undoubled, pass is forcing - partner must either double or bid.

[mikl_plkcc]

DavidKok, on 2025-February-18, 11:54, said:

[*]"Pass consults partner about defending versus bidding, and shows medium ODR": 1♠-(P)-2NT*-(5♣), where 2NT was a Jacoby 2NT. Here opener doesn't have many options, and a lot of people will reserve double as an offer to defend, any 5-level bid as a really aggressive hand, and pass as 'everything else'. It is asking partner to choose between defending 5♣X, playing 5♠, and trying for slam.

Why isn't it a situation where their 5♣ is makeable and our 5♠ will likely go down, so letting them play is the best option? If we compete on, how do we know how high to compete before letting them play undoubled?

[DavidKok]

 mikl_plkcc, on 2025-February-19, 09:44, said:

Why isn't it a situation where their 5♣ is makeable and our 5♠ will likely go down, so letting them play is the best option? If we compete on, how do we know how high to compete before letting them play undoubled?

You misunderstand.

• The 2NT was forcing to 4♠, expecting to make. The scenario you are describing corresponds to us having at most 10 tricks in spades and the opponents having at least 11 tricks in clubs, while we have the balance of strength. This is possible, but infrequent. Partnerships playing a forcing pass here agree to take a loss when passing out the opponents was best, in return for greater accuracy when it is not. Each partnership should decide what threshold is sufficient for them to agree that this convention is active. Importantly, all agreements work this way. There's always a chance that it backfires. We are simply playing with the odds, which are very favourable on this particular auction.
  
• The higher they bid, the more tricks they need to take. That makes defending undoubled less likely to be good, not more likely. It is quite common to agree to play a forcing pass "either if they interfere below the level of our force, or if we have shown requisite strength and the opponents interfere at a certain level or higher". You are free to make a different agreement, of choose.

[mycroft]

Shorter David: because you have already agreed with partner that 5♣ isn't likely to make, because you have agreed you have game *on power*.

Sure, it *might* make on even more extreme shape than is expected; and that same shape may mean that 5♠ will go down because the same ruffs happen on defence. But remember, even here you only win defending undoubled if *4♠* doesn't make; that is, if -400 is your best score. That's even less likely.

But almost always, when you have bid game *on power*, not "10 trumps ~= 10 tricks", either you can make 11 tricks, or they can't. Frequently both - and now the question is "is the set worth more than the make?"

So, in this situation, it is worth agreeing to lose to "they can make 11 tricks with their 13 HCP and amazing shape, and that will be our best score" (because it "never" will be) to try to guess better on whether to take the points or bid on and try to take 11. Remember that not everyone will be in this situation; some will let 4♠ play, and if you can't beat that on defence, it doesn't cost you that much more to try for x50 and maybe go down.

And hence, the forcing pass. 5♣ bidder's LHO can say "I don't think we can make 5♠" or "we're getting more than 4♠ was worth" by doubling; he can say "I think we should be able to make 11 tricks" by bidding, or he can say "My hand in this auction might go either way. What does your hand tell you?" without getting the embarrasing +150 or +200 when *one of those two* was the right answer (and maybe both. Or maybe 6♠). They also get the opportunity to show a slam try by passing, and then pulling the double: "Partner, I'm not sure 5♠ is *enough*. What does your hand tell you?" - another option not available if the pass isn't forcing.

And all that trades for "oh no, -400 is par" in situations where -400 is "never" par.

Yes, what is complicated - see MikeH's explanation that jillybean quoted - is "which auctions are 'bid game on power'?" I absolutely agree - and many of your "whatabout" hands come from not understanding that question. But if bridge was easy, we wouldn't play it.

[akwoo]

mikl_plkcc, on 2025-February-19, 09:44, said:

Why isn't it a situation where their 5♣ is makeable and our 5♠ will likely go down, so letting them play is the best option? If we compete on, how do we know how high to compete before letting them play undoubled?

Because your 5♠ won't be going down 3, so going down 2, even doubled, in 5♠ is better (at even or favorable vulnerability) than letting them make 5♣.

At neither vulnerable, 5♠ doubled down 2 is -300, but letting them make 5♣ is -400.

You will never want to let them play undoubled. 6♠ doubled down 3 is -500, but letting them make 6♣ is -920. 7♠ doubled down 4 is -800, but letting them make 7♣ is -1440.