Mark Carney called six federal byelections on Sunday, voting day December 7, and half of social media responded the same way: wait, doesn't he already have a majority?

Short answer: yes. Slightly longer answer: it's complicated, and the complicated part is the interesting part.

In April 2025, the Liberals won 169 seats. A majority in our 343-seat House takes 172. So Carney started with a minority, three seats short, needing somebody's help on every confidence vote. (House seat counts)

Then came the spring of 2026. The Liberals swept three byelections, in University-Rosedale, Scarborough Southwest and Terrebonne. Around the same time, five MPs crossed the floor to the government benches. Through that spring the Liberal seat count climbed to 174, two more than needed. For the first time in Canadian history, a government went from minority to majority between elections, without voters getting a say in the upgrade. (How it happened)

Since then, resignations have chipped away at it. Today the Liberals hold 173 seats with six sitting vacant. 172 is still the number, so the majority survives, but only just. That's the "thin majority" you've been reading about. (Current standings)

Now the six byelections. Here's what's up for grabs on December 7: (PMO announcement)

Brantford—Brant South in Ontario was Conservative. Larry Brock resigned in September to go back to prosecuting. The Conservatives are running Brantford mayor Kevin Davis, hand-picked by Poilievre with no open nomination race, which annoyed some local Tories. The Liberals have Joy O'Donnell. (Riding details)

Scarborough North in Ontario was Liberal. Shaun Chen stepped down with health problems after a car crash. It's a Liberal stronghold, and the party nominated businessman James Li.

Laurier—Sainte-Marie in Quebec was Liberal. Steven Guilbeault resigned in August. The Liberals are running Guy Cormier, the former Desjardins CEO.

Rosemont—La Petite-Patrie in Quebec was NDP. Saint-Hyacinthe—Bagot—Acton in Quebec was Bloc Québécois. The Liberals have nominated candidates in both.

Yorkton—Melville in Saskatchewan was Conservative. Cathay Wagantall resigned in August after taking 77.5 percent of the vote last year. Yorkton's mayor Aaron Kienle carries the Liberal banner against Conservative Nelson Pohl.

The Liberals come in with momentum and money: they outraised the Conservatives $4.9 million to $3.9 million in the third quarter, a reversal of the usual order. (Fundraising)

So what are the fairness questions here? A few worth sitting with.

First, the floor crossings. Five MPs were elected under one party's banner and now vote with the government. That's legal. It has always been legal. But the voters in those ridings chose a representative of a particular party, and they now have a representative of a different one, and nobody asked them. A majority built this way is constitutional... and it never appeared on a ballot. Both things are true, and the tension between them is the whole story.

Second, timing. The prime minister gets to call byelections, with months of leeway after a seat goes vacant. Governments call them when the moment suits them. That's the rule for everybody, but it's worth noticing who the rule favors.

Third, the nominations. Parties can parachute or appoint candidates, as the Conservatives did with Davis in Brantford—Brant South. Legal, common... and a reminder that the people choosing your options are not always the people voting.

There's a fresh cautionary tale sitting right next door. In September, B.C. Premier David Eby looked at his own one-seat majority, looked at a Conservative opposition cycling through leaders, and called a snap election two years early to turn his sliver into something comfortable. His stated reason was a fresh mandate to fight Trump's tariffs. Voters didn't buy it. The NDP fell to fewer than 30 seats, the Conservatives took a majority, and Eby resigned as leader on election night. (Report) (Recap)

Carney is attempting the same upgrade by quieter means. Six byelections instead of a province-wide gamble. No snap election, no grand ask, just seat-by-seat padding. It's legal, it's incremental, and it carries the same unanswered question: who is this for?

The December 7 byelections are the legitimate way to test where the country stands: six ridings getting a real vote. If the Liberals sweep the competitive ones, the thin majority gets thicker and nobody can say the voters didn't sign off. If they stumble, the questions get louder.

Carney's majority is real. The question to carry into December 7 is whether it was ever the voters' idea... and these six byelections are the first chance voters have had to answer that.

A nuanced take: Carney's majority is legal but was never voted for in its current form, and B.C. just showed what happens when voters conclude a leader's majority-building is about math instead of them.