You can do the right thing. Or you can do the thing that serves your country's interests best. Choose one.

That is the way foreign ministers have traditionally defined their job. They are realists who put national interest above all, or idealists who put universal values and principles first. Richard Nixon and Jean Chrétien portrayed themselves as hard realists. George W. Bush and Stephen Harper started out as committed idealists. Those convictions all collapsed, eventually, on the hard pavement of real events.

Justin Trudeau's election campaign was an attempt to blow the silver bugle of liberal idealism, proposing a more principled

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foreign policy far removed from the Conservatives' single-issue pipeline politics and the scorn for international institutions.

But that tune was drowned out, days into office, by the sad trombone of real-world entanglements. A huge Canadian arms sale to Saudi Arabia could not be escaped easily without messing up Canada's political and economic interests. An ostensibly principled pledge to avoid aerial bombardment made Canada's already paltry contribution to the Syria campaign look to many like a retreat.

This was thus an awkward week for Foreign Minister Stéphane Dion to make a major speech defining Canada's new approach to the world. Then again, it forced him to be honest about the limits of a medium-sized country's foreign policy. The old tropes of "Canada first" or "not going along to get along" were not going to work.

In the heady years that began this century, the debate was about means and ends: Someone such as Mr. Dion might have turned to Immanuel Kant, who argued that we should take actions in the world only if our motives and methods are pure and principled, or to John Stuart Mill, who argued that all that really matters is the end result, and it is worth taking whatever actions are necessary to achieve a beneficial outcome. (The Iraq War debate was a feud between those two perspectives.)

But this is 2016, a chastened time. The failures of Iraq and Afghanistan tend to have thrown both means and ends into question.

So Mr. Dion instead turned to Max Weber, the father of modern sociology (and also, not insignificantly, of modern bureaucracy), whose masterpiece Politics as a Vocation defined something resembling the Kant perspective ("ethics of conviction") and the Mill approach ("ethics of responsibility").

Mr. Dion coined a rather bland-sounding catchphrase that combines both: "responsible conviction." This formulation, he said, "means that my values and convictions include my sense of responsibility."

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That might sound impossibly vague and all-encompassing – and open to mockery – but the speech does a decent job of laying out its implications: Yes, Canada will make climate change, opposition to capital punishment and promotion of reproductive rights its big priorities. But it will also actively engage (and do business with) Iran and China, countries that tend to betray those principles, in hopes that this is the best way to bring them out of the cold.

It's strikingly similar to the foreign-policy approach Barack Obama described in a recent interview: He drew a "four-box grid representing the main schools of foreign-policy thought" – isolationism, realism, liberal interventionism, internationalism. He rejected isolationism outright as "untenable" and recoiled from liberal interventionism, after its recent failures. But he embraced both internationalism and realism: "We can't, at any given moment, relieve all the world's misery. We have to choose where we can make a real impact."

If these philosophies seem like disappointing justifications for non-action, they partly are. The seeding of democracy across an entire region through imposed regime change is no longer a popular image. Risky acts of principle are out of fashion.

But some of Canada's best moments have come when we have defied self-interest and taken single, principled actions. Our decisions in the 1980s to back the African National Congress in its fight against apartheid, in the 1990s to recognize Ukraine's independence, in 2003 to have Canada stay out of the "coalition of the willing" in the Iraq invasion all infuriated our allies, but were right in retrospect.

If "responsible conviction" can include not just bland co-operation but a few such explosions of defiant principle, then maybe the phrase will have some meaning.