The Liberal government's approach to foreign policy is to be rooted in the concept of "responsible conviction," a shorthand which Foreign Affairs Minister Stéphane Dion outlined in a philosophical speech on Tuesday.

Dion added some gravitas to Prime Minister Justin Trudeau's mantra that Canada "is back" in world affairs, saying the idea of "responsible conviction" offers a blended approach, in which values and convictions are tempered with a sense of responsibility.

This, he added, will be the guiding principle for a new approach to foreign relations.

The minister said the concept explains how the new policy can incorporate some of the practical ideas of the former Conservative government, while seeking to reverse what he called the previous government's "disengagement" approach to global affairs.

"This formulation means that my values and convictions include the sense of responsibility," Dion said.

"Our government shares the same conviction as the previous government, but it assesses the consequences of its chosen method of promoting this conviction differently."

His speech, which drew some inspiration from Max Weber, a 20th century German sociologist, prompted one of Canada's leading international figures to caution against a slide into nostalgia and partisan politics.

Louise Arbour, a former justice of the Supreme Court of Canada and one-time lead prosecutor for the International Criminal Court in The Hague, said there was a lot to like about Dion's speech to a University of Ottawa conference.

But, she added, the new government needs to do more than just hearken back to the past when the likes of Lester Pearson and Lloyd Axworthy made high-profile contributions to world peace and security.

She also hinted that the Liberals might want to extend an olive branch to those not inside their political tent.

"The danger is nostalgia, cheerleading, speaking only to the like-minded," Arbour told a panel discussion. "This is not the way to go. ... We need to talk to people who disagree."

Arbour, who left her mark internationally when she indicted former Serbian president Slobodan Milosevic for war crimes in the 1990s, offered her own label for a foreign policy direction.

"I think it's a kind of principled pragmatism that's going to allow us again to punch above our weight," she said.

Re-opening channels with Iran, Russia

Dion repeated that Canada will have a new focus on multilateralism and the United Nations. The new approach means re-engaging the United States, fighting climate change, talking to Russia and Iran, opposing the death penalty for Canadians in prison abroad and taking on a different role in the fight against Islamic State of Iraq and Syria.

Dion said the new concept means the Liberals can share common ground with the former government, carrying on its maternal and newborn health initiative, with added money for abortion and family planning, and continuing to sell billions in military hardware to Saudi Arabia.

The minister defended the controversial decision by the Conservatives to sell $15-billion in light armoured vehicles to the Saudis. The Liberals are upholding the deal despite loud protests about Saudi Arabia's crackdown on dissent and its subjugation of women.

Dion said cancelling the contract would put thousands of Canadians out of work and harm the country's international reputation in other ways.

He said the government intends to ensure that future export permits conform to Canadian interests, including the promotion of human rights. He also said if Canada doesn't sell military hardware to the Saudis, others will.

Arbour didn't buy that explanation.

"This argument, that if we don't do it somebody else will do it, I find frankly the least convincing," she said.

Emyr Jones Parry, a former British ambassador to the UN, said Dion's speech signaled a positive re-engagement globally, including with the UN.

"Most of the world would be very ecstatic to hear that is the government's intention to take Canada back to where it rightfully belongs," he told the gathering.

Dion said Canada will have its eyes open as it re-establishes communication with authoritarian regimes such as Iran and Russia.

He also also recast Canada's so-called honest broker role in foreign policy, which the Conservatives scorned as a sign of weakness.

"Since the classic concept of the honest broker is now too often confused with moral relativism or the lack of strong convictions, I prefer to say that Canada must be a fair-minded and determined peace builder."