They used Tu Vi, an ancient belief system in Vietnam with Taoist roots stretching back to at least 16th century China. Tu Vi offers individuals and couples predictions about future events—such as marriages, births, deaths, business prospects, and travels. These are based on a person’s birth time and moon year of birth in the 12-year zodiac.
Tu Vi’s popularity in Vietnam has ebbed and flowed throughout the 20th century and regained widespread popularity in the last 30 years. But little is known about whether these kinds of religious belief systems, which are independent of any institution or doctrine, influence people’s behavior.
Specifically, Nguyen wondered how much these beliefs actually matter to couples when it comes to making marriage decisions. He also wondered: What are the consequences for their marriages if they have what Tu Vi considers an auspicious match?
In addition, they also found that couples in what are considered happy marriages benefit in measurable ways: they earn more and have a higher standard of living, for example, and their children are less likely to drop out of school.
Which is not to say that the stars were right in their predictions. Nguyen says there’s a self-fulfilling prophecy at work: when a couple’s social circle believes a marriage is auspicious, they’re more likely to step in and offer help, helping the couple through difficult times.
“Happy couples actually end up doing better, and this belief is passed down from generation to generation,” says Nguyen.
Evaluating how important Tu Vi is
The researchers partnered with a think tank to conduct a survey of ethnic Vietnamese in 2020. The results highlighted how widespread Tu Vi is: eighty-two percent knew about the system and how to get information for detailed predictions. 45 percent believed that their family and relatives care about Tu Vi. and 31 percent considered Tu Vi to some extent in their own marriage.
To understand how these beliefs in marital fate affect marriage formation, the researchers turned to census data as well as data from the Vietnam Population Survey, focusing specifically on four regions of the country, two urban and two rural. From the 2009 census, they analyzed a sample of 916,314 married couples. The women in this sample ranged in age from 19 to 33, while the men ranged in age from 21 to 35. The researchers also analyzed similar, but smaller, paired data sets in the 1989 and 1999 censuses, as well as Population Survey data from 2006–2018. In total, the different samples include 1.36 million pairs.
Using information about when each spouse was born, the researchers were able to see how auspicious each match was considered. They found that 34 percent of the matches were auspicious (about half a percent higher than expected from random matching), 53 percent were neutral, and 14 percent were inauspicious (about 3 percent lower than random assignment).
Overall, the researchers found that Tu Vi plays a role in shaping marriages and was actually about 6 to 7 percent as important in marriage matching as the couple’s education and age. Auspicious marriages were more common in provinces where religious observance is higher and social ties stronger, and occurred less often in wealthier areas. But no matter how many variables the researchers looked at, they still found evidence of auspiciousness.
“When we try to account for a lot of other things, like education, age, or the area you live in, auspiciousness still comes into play,” says Nguyen.
What is the impact of a favorable marriage?
The researchers then wanted to understand whether couples in favorable marriages were better off than those in unfavorable matches.
To their surprise, the answer appeared to be yes. The survey data showed that those in favorable marriages earn 2.2 percent more and have household expenses that are 2.7 percent higher than others in their socioeconomic and educational class. They also have a better self-reported standard of living and their children are less likely to fall behind in school.
What drives this good fortune? Nguyen attributes this to the greater support from friends and family of a favorable couple, especially during difficult times. On the other hand, friends and family may see unhappy couples as likely to fail anyway and therefore not worth the extra help.
Indeed, auspicious couples enjoyed 9 percent more support on average than couples who did not follow Tu Vi beliefs, according to the survey data. Lucky couples who were poor were 18 percent more likely to receive such support, while lucky couples who were caring for a family member received 24 percent more support. Such couples are also less likely to be forced to liquidate their assets or take loans from formal institutions (as opposed to friends and family).
Like other values and norms, belief in the auspiciousness of marriage has persisted because it has been passed down through generations and reinforced through community, Nguyen says.
“Even if the couple themselves don’t really believe in it, but they think their family and friends do, there’s an incentive for them to match favorably — if it’s important that they get help from family and friends when you go through difficulties. ” she says.
Having examined the effect of Tu Vi on marriages, Nguyen and her colleagues plan to next study the impact of auspicious beliefs on business relationships. As Tu Vi becomes more popular, researchers are seeing an increasing number of ads from small business owners looking for partners or employees who are a good match.
“There’s definitely something going on,” says Nguyen, “but how big or how important, we don’t know yet.”