This week, a unique event occurred: A group who call themselves the Bogleheads held an investment conference near the Philadelphia headquarters of Vanguard Group. Since its inception in 2000, this annual gathering has brought together dedicated fans of the late Jack Bogle, Vanguard’s founder.

Jack Bogle was beloved by his fans for his authenticity and for his iconoclastic views. He was so self-assured, in fact, that after he retired from Vanguard, he didn’t hesitate to share his opinions, even when he was in the minority and even when he disagreed with Vanguard’s official position.

Among the points on which Bogle disagreed with Vanguard was the question of international diversification. For decades, until the end of his life, Bogle was consistent in his view that investors need not—and probably should not—diversify their portfolios outside the United States. Bogle said that his own portfolio was 100% domestic, and he recommended that others do the same. Vanguard’s official position, on the other hand, was that investors should structure their portfolios to mirror the overall makeup of world markets, of which the U.S. is just 50%. At the very least, Vanguard recommends that investors allocate 40% of their stocks to international markets.

In Bogle’s view, there was no need for international diversification because the U.S. is, “the most innovative economy, the most productive economy, the most technologically advanced economy and the most diverse economy.” And to the extent that an investor did desire exposure to foreign markets, Bogle pointed out that domestic companies derive such a large part of their revenue—nearly 50%—from outside the U.S. that it was unnecessary to buy the stocks of foreign companies. “If you own a domestic stock fund, you already own an international fund,” he said. And finally, Bogle highlighted a number of risks, including currency depreciation and more limited shareholder protections outside the U.S. For all those reasons, he said, “I don’t do international.”

Vanguard’s official view, on the other hand, is based on the logic that investors shouldn’t exclusively favor one country’s stock market just because that’s where they happen to live.

My view: I believe international diversification is useful, but I absolutely worry about the risks that Mr. Bogle always cited. And even Vanguard’s own data indicate that a large majority of foreign stocks’ diversification benefit can be achieved with an allocation of just 20%, which is why that is what I recommend.

I’ve been thinking about this more in recent weeks as the protests in Hong Kong have raged and as the NBA has found itself mired in controversy just because the general manager of the Houston Rockets issued one tweet that Chinese authorities did not like. Even after deleting the offending tweet, the economic fallout for the NBA has been hard-hitting.

These events reinforce my view that, though the U.S. is hardly perfect, our economic system is much less imperfect than many others. And this is why I am happy to limit exposure to international stock markets—and especially emerging markets, where limitations on individual freedoms and government interference in the economy are both more prevalent.

But ironically, for the very same reason, I still wouldn’t recommend taking your international allocation to zero. Recently, the Wall Street Journal described how the consumer market in China has changed in recent years. Owing in part to improvements in domestic brands as well as to growing patriotism, Chinese consumers have moved in large numbers away from foreign brands. Over the past ten years, for example, foreign smartphone manufacturers have lost a dramatic 78 points of market share in China. Today, Apple is down to just 9% there, while four Chinese vendors dominate the market with a combined 84%.

The implication for investors: Owning stocks in American companies may no longer provide sufficient diversification. In the past, it may have been enough to own companies like Apple, Nike and Hershey, since each had such broad international reach. But if they are at risk of having their wings clipped outside the U.S., and particularly in China, you may want to broaden your portfolio to also include their Chinese competitors Huawei, Li Ning and Three Squirrels.

No question, I share Jack Bogle’s concerns about international markets, but for the benefit of your portfolio, I do recommend continuing to keep one foot—very carefully—overseas.