Semyon Dukach is an entrepreneur and angel investor in Boston, known for his role in the MIT student blackjack team.

The drastic increase in Americans’ life expectancy over the past century has shifted the balance of power between the old and the young. In the United States, voting begins at 18, but voters are typically living until their 80s, decades longer than they used to. Political power has shifted toward people in the sunset of their lives, and it is probably no coincidence that the country has taken on massive debt not to invest in its future but largely to address the medical and material needs of retirees.

Prudent personal finance shows that it can be productive to use long-term debt to fund investments that have a greater potential return than the interest rate, such as financing a house, starting a business or obtaining an effective education. But borrowing over prolonged periods will succeed only in incurring ever greater amounts of debt, unless this borrowed wealth is used for some kind of productive investment.

Investments in new transportation or clean-energy infrastructures, expanded exploration of science and meaningful education reform are long-term. They will bring no direct benefits to older people and limited benefits to the middle-aged but huge benefits to their children and the next generation. Who is more likely to politically support such investments — seniors who depend on Medicare and Social Security and who only occasionally interact with young people, or working parents who think every day about their responsibilities toward their children? Yet our increased longevity has transferred political power from young parents to grandparents, with the disastrous — although natural — consequence of national under-investment in our future.

Three major extensions of voting rights have been implemented since our republic was founded. The 15th Amendment extended suffrage to former slaves after the Civil War. The 19th Amendment gave women the right to vote in 1920. And the 26th Amendment lowered the voting age from 21 to 18, to match the draft age during the Vietnam War.

There is one clear path for our nation to navigate today’s crisis of political deadlock, growing debt, and under-investment in infrastructure, core science and education. We must lead the world by expanding our democracy and amending our Constitution. We should include those who remain unrepresented in our democratic process: children.

The most straightforward solution to reasonably represent the interests of children younger than 13 is known as “Demeny voting,” after the demographer who raised the issue in the 1980s. Under the Demeny system, the parents or guardians of these children split the vote of each child. In cases in which legal custody is shared between a father and mother, both would control an additional half-vote at the polls for each of their children age 13 and younger.

For example, if a couple has two children, each parent would wield two votes (one each for themselves and a half-vote for each child). A family of four would have four votes. In a family of five, with two adults and three children, each parent would have 2.5 votes (one for themselves and 1.5 for the three children). Again, this adds up to the total number of people in the family. If a single parent had sole custody, he or she would get the entire extra vote.

For adolescents, a simple variation of the Demeny voting scheme could allow them to be gradually emancipated. They could cast 20 percent of their vote at age 14, 40 percent at 15, 60 percent at 16, 80 percent at 17 and 100 percent at 18 (as they may today). The remaining diminishing percentage of their vote would be split each year between their parents or legal guardians, just as in Demeny voting, so that the total number of votes eligible to be cast in the nation will always be equal to the total number of citizens of all ages.

This voting scheme has drawbacks, including that it gives excessive power to parents of large families. And some parents might vote to protect their own interests instead of their children’s. But it would still be a crucial improvement over the status quo. Giving people younger than 18 indirect political representation will result in a more forward-looking balance of power among Americans. It would enable more political investment in our children’s future. Most important, by completing our national journey from a country ruled by landowning white men to one run on the principle of “one person, one vote,” we would lead the world in securing the inalienable universal human right to democratic representation.