Pete Buttigieg worked nearly three years for the consulting firm McKinsey & Company, and he has presented that experience as a kind of capitalist credential — distinguishing him from some rivals for the Democratic presidential nomination, and inoculating him against Republican attacks.

“They’ll try the socialist thing,” Mr. Buttigieg told an Iowa audience in September, referring to a likely line of attack by President Trump and his allies against whichever Democrat emerges as his opponent in next year’s election, “but the thing is, I got started in the private sector.”

The thing is, Mr. Buttigieg has said precious little about his time at McKinsey. He has not named the clients for whom he worked, nor said much about what he did. He says his lips are sealed by a nondisclosure agreement he signed when he left the firm in 2010 and that he has asked the company to release him from the agreement. It has not yet agreed to do so.

This is not a tenable situation. Mr. Buttigieg owes voters a more complete account of his time at the company. Voters seeking an alternative to Mr. Trump should demand that candidates not only reject Mr. Trump’s positions, but also his behavior — including his refusal to share information about his health and his business dealings. This standard requires Mr. Buttigieg to talk about his time at McKinsey. It similarly requires Joe Biden and Senator Bernie Sanders to stop dragging their feet and release their health records to the public.