Justin Trudeau, and even less Yves-Francois Blanchet, do not want to show any openness whatsoever for the idea of a coalition government.
It is understandable that in election, a party leader who aspires to power like Trudeau refuses even to consider being a minority.
It would be a form of abdication. In politics, many statements are "performative", that is, they help create what they say. For example, a finance minister who admits that a recession is brewing may accelerate it just by talking about it.
Similarly, a party leader who agrees to consider a coalition favors the bursting of his vote.
Here is how Jagmeet Singh's perspective on this issue can be explained. At the end of the week, he was initially open to considering a coalition with the PLC to prevent the Conservatives from taking power.
But yesterday, it multiplied the nuances, even it receded.
At first glance, would not it be refreshing, a coalition government?
Since partisanship is one of the things citizens hate most about politics, they would no doubt see in a multiparty executive a kind of star team of people united for the common good.
The Green Party is proposing a multiparty "war cabinet" to deal with climate change.
Not very practical
In practice, it's more complex. The British conservatives and lib-dem tried it almost a decade ago, and it was damaging for the last ones.
In the history of our Dominion, it is an absolute rarity.
There were governments of this type before Confederation. Then, it was not until 1917 that Robert Borden, struggling with fierce opposition to conscription, formed a "unity government" by inviting Liberals and independents to join his cabinet.
Closer to home, there was a coalition attempt in 2008, where the Liberals of Stephane Dion and the New Democrats of Jack Layton wanted to propose to the Governor General to form a joint government with the support of … the Bloc Quebecois.
Stephen Harper, who had just won a plurality of seats without having the majority, denounced a near-coup! To be sure of blocking the thing, he closed the parliament!
The adventure was damaging especially for Dion and the Bloc. Look no further for Yves-Francois Blanchet's source of mistrust of this idea.
It is the same type of fear that led Pauline Marois, in 2012, to reject the idea of his minister Jean-Francois Lisee to form a coalition government with ministers of the CAQ and QS.
Basically, the only "coalitions" that our voting system and our culture accept are those where one party swallows others before coming to power. This is the case of the "Coalition" future Quebec Legault.
It would be very surprising if, in the aftermath of the next federal election, the government in Ottawa was one of coalition or union.