Antonin Scalia’s death has caused political tumult. But we should have seen it coming. Scalia was a month shy of 80.

The U.S. Supreme Court’s elderly membership indicates a strange blindness about mortality and old age. Justice John Paul Stevens retired in 2010, at age 90. Justice Anthony Kennedy is nearly 80. Justice Ruth Bader Ginsburg is almost 83. Since so much depends on the longevity of the justices, it’s natural to wonder whether there should be a mandatory retirement age.

Socrates was content to die at 70, yielding his place in the race, as he said, to younger and faster runners. Dare we ask: how old is too old to run a country?

These days 70 seems young. Older people keep on running. Ronald Reagan – who appointed Scalia – was the oldest president. Reagan left office at 77. If elected, Bernie Sanders would be 75 on inauguration day. Gov. Jerry Brown is 77. Sen. Dianne Feinstein is 82.

Sumner Redstone, chairman of Viacom and CBS, resigned this year at age 92 amid rumors of failing health. Other aged execs include Rupert Murdoch, who is 84, and Warren Buffett, who is 85.

Given all of these active elders, it seems wrong to judge people based on age. It’s ability that matters, after all.

But does that same principle apply at the other end of life?

California Assemblywoman Lorena Gonzalez is leading an effort to lower the voting age. Citing studies that show little difference between the deliberative power of 18-year-olds and 16-year-olds, Gonzalez wants to allow 16- and 17-year-olds to vote in school board elections.

We might protest that children are uninformed and immature. But some 16- and 17-year-olds are as informed and mature as some adults. Malala Yousafzai won the Nobel Peace Prize at 17. Perhaps we should trust 16-year-olds with the franchise if we trust them to drive cars and flip burgers.

If we prevent young people from voting because we don’t trust their rationality or the independence of their judgment, what about those at the other end of life, who are dependent or who suffer from dementia?

It seems like ageism to say that people are too young or too old. Some 84-year-olds are vibrant, smart and engaged. So are some 14-year-olds. And some 44-year-olds are ignorant and uninformed.

Our age limits seem arbitrary and unfair. 18-year-olds can vote and join the military. But they cannot drown their sorrows after battle. Nor can 18-year-olds run for national office. You must be 25 to be elected to the House, 30 to be elected senator, and 35 to be elected president.

Those age limits are antiques of the pre-Facebook era. Mark Zuckerberg started Facebook before he was old enough to drink. Zuckerberg is one of the most powerful men on earth. But at 31, he is still not old enough to run for president.

One modest proposal would eliminate age as a criterion by focusing on skills. We could test individuals for maturity, rationality and basic knowledge. We have a test for driver’s licenses. Why not also create a licensing exam for voting, drinking or serving in office?

Of course, that sounds quite undemocratic. We let adults vote without examining their knowledge, maturity or decision-making skills. We also let people run for office without testing their IQ.

Behind all of this, there is a basic conflict between respecting people as individuals and creating social policy for the masses. In dealing with age, we generalize. But general rules often unfairly impinge on the rights of individuals.

Someday a 30-year-old president may meet with a 100-year-old Supreme Court justice and laugh about the bad old days when 16-year-olds were too young to vote. In the meantime, we need careful reflection about age and ageism – and honest discussion about the role of youths and the elderly in our society.

Young people would learn to be better citizens if they were encouraged to participate. Old people do better when they remain active and engaged. And everyone needs to acknowledge that it is impossible to outrun death.