Introduction
There are some bridge rules that we have not encountered yet, namely vulnerability and doubles/redoubles. These two topics will be important particularly since we will discuss competitive bidding soon.
Note: both of these elements affect scoring. If you are interested in learning more about how each deal is scored, check out this article.
Vulnerability
For each board, one partnership can be either vulnerable or non-vulnerable. As a result, there are 4 possible vulnerabilities for each deal: None, North-South, East-West, or Both. The specific vulnerability depends on the board number and it follows a cycle of 16. If EW is vulnerable, we say they are “red”. If EW is non-vulnerable, we say they are “white”.
Vulnerability plays a role in scoring:
If the declaring side is vulnerable,
if they make the contract, they get more points if the contract is a GAME or SLAM.
If they do not make the contract, they lose more points.
If the declaring side is non-vulnerable,
If they make the contract, they do not gain as many points if the contract is a GAME or SLAM
If they do not make the contract, they do not lose as many points.
Vulnerability Examples
Making 4S red = +620 Making 4S white = +420
Making 3S red = +140 Making 3S white = +140
Only games/slams are affected by vulnerability when the contract is made, NOT part scores
Going down 2 red = -200 Going down 2 white = -100
Each vulnerable under trick loses you 100 points, each non-vulnerable under trick loses you 50 points
Double
Instead of making a bid on your turn, you can choose to “double” (dbl) if the latest bid is made by an opponent. A double is obviously not a pass, so 3 consecutive passes after the double will end the auction.
(Fig. 1: Here, the right-hand opponent bids 2D, so double is a valid option)
(Fig. 2: Here, since the last bid is still made by an opponent, double is a valid option)
(Fig 3: Here, since your opponents did not make the last bid, double is not a valid option)
Redouble
You can only redouble when your opponent has doubled your side’s contract (bid by either you or your partner). 3 passes after a redouble will end the auction.
(Fig 4: Here, since your partner’s bid is doubled, redouble is a valid option)
(Fig 5: Here, since your bid is doubled, redouble is a valid option)
Purpose of doubles and redoubles
So, what is the purpose of doubles and redoubles?
In simple words, you double an opponent’s contract to say that “I am pretty sure the opponents cannot make it” and you redouble a contract to say that “I am pretty sure I can make it.”
In terms of scoring, a doubled contract will result in a higher score for the defenders if it went down and will reward the declaring side more if it was made. In essence, a double raises the stakes for both sides. Therefore, in the beginning, doubles are intended to punish the opponents for bidding overly ambitious contracts. For instance, if your opponents are in 7NT and you are on lead with an A, you know for sure that the contract is going down. Then, you may choose to double to penalize them.
Similarly, a redoubled contract further raises the stakes for both sides. Therefore, the original meaning of redouble is punishing your opponents for believing that they can beat you. If you hold the AKQJT98765432 of spades and your opponents double you in 7S, you would obviously redouble them since you cannot go down.
However, the penalizing aspects of doubles and redoubles are less prevalent at lower-level contracts. It is much easier to guarantee to beat 7NT than it is to beat 1NT. As a result, doubles at lower levels are only rarely for penalty. The most frequent use of double is in fact what is known as “takeout double”. A takeout double usually shows shortness in the suit that the opponents bid and length in the other suits, asking partner to bid one of the unbid suits. Read more about all the different kinds of doubles.
Since low-level doubles are not meant as penalty, redouble to say that you can guarantee to make a contract would not work since the opponents can simply bid something else. Therefore, redoubles are often used to show other hands, for instance, strong hands without a clear bid otherwise.
Double Examples
(1C)-x (3C)-x (4C)-x
(1D)-x (2D)-x (3D)-x (4D)-x
(1H)-x (2H)-x (3H)-x (4H)-x
(1S)-x (2S)-x (3S)-x (4S)-x
These doubles are all takeout, not penalty!