Policy, not personality, takes centre stage at VP debate, but to what end?

Voters in the United States and viewers around the world might have been pleasantly surprised to watch vice-presidential hopefuls JD Vance and Tim Walz debate each other in a civil manner on Tuesday in New York City. For more than 90 minutes, the candidates answered questions about topics ranging from foreign policy to domestic policy.

The substantive debate stood in in stark contrast to presidential debates in years past that have focused more on personality than policy.

Throughout the debate, Vance and Walz engaged in a respectful and informative conversation, despite their policy differences. At several points, they even went out of their way to highlight points of agreement and show appreciation for one another.

After Walz stated that his teenage son had witnessed a shooting, Vance expressed how sorry he was to learn about this. "I appreciate that," said Walz, in what appeared to be a moment of genuine humanity too often missing from partisan politics today.

While the evening highlighted the key differences between the two major parties running in November, and gave viewers a deeper look at both candidates, did it move the needle in any way for voters?

Big differences

In talking about domestic policy, Vance and Walz highlighted the main positions held by the presidential candidates at the top of their party ticket.

For example, Vance echoed Trump's position that states should be able to decide whether, and if so under what circumstances, to legally permit abortions. He also refused to back a federal ban on abortion, which he had supported before joining Trump's ticket.

Walz, in contrast, echoed Harris in calling for passage of a federal law codifying the recently-overturned Roe v. Wade Supreme Court ruling, by guaranteeing a right to abortion across all states.

They also disagreed on other major domestic policy issues, including migration, health care, and economics.

However, their foreign policy differences were less clear. In response to the first question of the debate, about Israel's potential response to yesterday's missile attacks by Iran, Walz endorsed Israel's right to defend itself and called for the return of its hostages - while also calling for an end to "the humanitarian crisis in Gaza."

Vance described his position only briefly, by stating "it is up to Israel what they think they need to do to keep their country safe… when they're fighting the bad guys."

One must be careful not to read too much into this exchange about foreign policy. Vance and Walz differ quite a bit on other foreign policy matters, including the war in Ukraine and Trump’s proposed tariffs on foreign goods (particularly from China).

But the debate moderators did not ask about those issues. Nonetheless, their first question provided some important insights when it comes to the next administration’s policy regarding the Middle East, and US relations with Israel in particular: Vance and Walz both endorse a close partnership with significant military support.

Who won?

Perhaps the most dramatic moment in the debate came in response to a question about the previous elections in 2020.

Walz asked Vance pointedly whether Trump had, in fact, lost that election. Vance would not say yes or no. His strained response was aptly described by Walz as a "damning non-answer."

So who "won" the debate? Opinions may vary, especially depending on one's policy or partisan preferences. But in the days following a debate, a consensus often emerges as to what the big moment was and who benefits from it.

Democrats may point to Vance's unwillingness to acknowledge that Trump lost the 2020 elections. Republicans may point to Walz's flummoxed and confusing explanation of past misstatements regarding him being in China during the Tiananmen Square.

Will media coverage, or social media, focus on one of these moments in the coming days? Or something else? That may determine who comes to be seen as the winner of last night's debate.

Post-debate polls by CBS and CNN effectively declared it a draw, with Walz trailing slightly behind Vance but within the margin of error. Vance, to this point the most unpopular vice-presidential candidate in modern history, may have made some gains in that regard.

His net favorability ratings improved from a woeful -23 percent before the debate, to a respectable -3 percent afterward, according to CNN. And from -14 percent to +2 percent, according to CBS.

But that pales in comparison to Walz, who already entered last night with the highest net favorability ratings of any candidate in the race. His ratings improved to +37% according to CNN, and +25 percent according to CBS.

Did the debate matter?

Regardless of who won the debate, the bigger question is: what difference will it make in November? Will Vance's or Walz's performance sway the outcome of the 2024 presidential election?

Probably not. First, debates rarely influence election outcomes. Sure, they may move the polls slightly for a few days. But in most cases, these shifts are only temporary, as later events reinforce the partisan preferences of those voters who had backed away from the candidate who had a bad night on the debate stage.

Second, as Kyle C. Kopko and I demonstrate in our book, "Do Running Mates Matter?", vice-presidential candidates have very limited effects on presidential voting. People generally do not vote for or against a presidential ticket because they really like or dislike the vice-presidential candidate.

Rather, voters focus on the top of the ticket, recognising that the US Constitution affords presidents far more power than vice presidents. To the extent that running mates matter, it is because they are a reflection upon the presidential candidate who picked them in the first place.

In that case, it is better to focus not on who won last night's vice-presidential debate, but what that debate might have told voters about Trump or Harris.

Did Vance and Walz come across as credible vice presidents who could even take over as president, if necessary–particularly given Trump’s advanced age, at 78, and President Biden’s decision to withdraw from the presidential race in July due to age and health concerns?

Do they have the temperament and judgement to lead the United States and coordinate with allies? Do they hold views that are within the mainstream of American politics, or are they too extreme?

How voters answer these questions, now and in the coming days, may tell us whether the debate actually mattered—and which ticket, if any, benefited from it.