TUESDAY NIGHT’S vice presidential debate was more of a proxy war between this year’s presidential candidates than a contest about capabilities of the two men on stage. In that sense, it was an unfair fight: Gov. Mike Pence (R-Ind.) had to defend the indefensible Donald Trump. To a large extent, he did so by conjuring a candidate who does not exist — a Reaganesque supporter of a muscular foreign policy, small government and traditional Christian values. It was as if he was defending the running mate he wished he had.

To the extent that Mr. Pence succeeded Tuesday evening, it was in landing blows on Hillary Clinton while declining to defend Mr. Trump’s proposals and record. When Sen. Tim Kaine (D-Va.) listed a variety of Mr. Trump’s offenses — from stoking the racist “birther” movement to attacking Sen. John McCain’s war record to calling women disgusting names — Mr. Pence responded by claiming Ms. Clinton and Mr. Kaine have run an insult-rich campaign.

Similarly, when challenged to defend Mr. Trump’s plans for the budget and entitlement programs, Mr. Pence insisted the Democrats would create “a mountain range of debt,” though Mr. Trump’s tax-cutting plan would, in fact, balloon the debt much more. Mr. Pence played down Mr. Trump’s promises to deport millions of undocumented immigrants and his well-documented skepticism of NATO. He frequently insisted that Mr. Trump would be “strong” where President Obama and Ms. Clinton are “weak,” attacking them for “Russian aggression” under their watch, but he dodged when Mr. Kaine pointed out that Mr. Trump has cozied up to Russian dictator Vladimir Putin.

Mr. Pence’s all-purpose defense of Mr. Trump was that “Donald Trump is a businessman, not a career politician.” He deployed this line when attempting to explain why Mr. Trump has failed to release his tax returns. But the fact that Mr. Trump lacks a public record to scrutinize makes it only more important that he release his tax returns, so the public can see how he conducted the professional life on which he bases his campaign.

This is not to say Mr. Kaine shined. His frequent interruptions made his points about Mr. Trump, which were mostly reasonable, seem less so. Mr. Pence effectively bore in on areas of the world that have becomes less stable during the past eight years. Both candidates, meanwhile, failed to respond to a range of substantive questions from moderator Elaine Quijano. Neither ticket, for example, has a plan to take on the nation’s long-term budget imbalances. Both candidates said that, unlike Mr. Obama, they favor creating a safe zone in Syria, but, when pressed, neither explained how or by whom that zone would be protected. A break from the dodging and insulting came when they thoughtfully debated abortion, with both men fervently defending their very different points of view.

Repeatedly over the course of Tuesday’s debate, Mr. Kaine exclaimed that he could not believe Mr. Pence could defend Mr. Trump’s behavior and record. In a way, Mr. Kaine was right — a polished Mr. Pence largely did not.