This article originally appeared in The New York Times If you’d like to know where American political debates are headed, the data suggest a simple answer. The next major struggle — in economic terms at least — will be over whether taxes on personal wealth should rise — and by how much. The mathematical reality is that wealth is becoming more important, relative to income. In a new paper,“Capital Is Back: Wealth-Income Ratios in Rich Countries 1700-2010,”Professors Thomas Piketty and Gabriel Zucman of the Paris School of Economics have performed the heroic task of measuring wealth for eight leading economies: the United States, Canada, Britain, France, Italy, Germany, Japan and Australia. Their estimates reveal some striking trends. For instance, wealth accumulation in these eight countries has risen relative to yearly production. Wealth-to-income ratios in these nations climbed from a range of 200 to 300 percent in 1970 to a range of 400 to 600 percent in 2010. Behind the changing ratios is some bad news, namely that slow productivity growth and slow population growth have depressed income growth, but also some good news — that relative peace and capital gains have preserved wealth. Focusing on the wealth of economies lets us reframe our recent debates about government debt in useful ways. A look at the ratio of debt to gross national product, for example, can be scary, but the ratio of debt to wealth is far less forbidding. If, say, a nation’s debt-to-G.D.P. ratio is 100 percent — often considered a dangerous level — and national wealth is 10 times yearly national income, the debt-to-wealth ratio is thus 10 percent, which is comparable to owing $100,000 on a $1 million home. Not so scary. Using the wealth numbers provided by Professors Piketty and Zucman, we can understand how Japan, despite a debt-to-G.D.P. ratio of more than 200 percent, can maintain low interest rates; Japan has a wealth-to-income ratio of about 600 percent. In essence, creditors think the Japanese political system will be able to drum up enough support for the requisite taxes, pulled out of national wealth if necessary, when the time comes. But don’t relax too quickly, because fiscal problems remain very real for many countries. While virtually every government could pay off its debts by taxing wealth, such taxes are often politically unacceptable. In other words, fiscal problems are best regarded as problems of dysfunctional governance. In the…