Proportional representation would lead to more coalition governments representing a wider range of public opinion than the one-man one-party government we saw from 2006 to 2015.
Some Progressive Conservatives and democratic-reform conservatives may not agree with this description of the last government. However, they had their own coalition: from Sept. 24, 2001, to April 10, 2002, 19 MPs sat as the PC-DRC Coalition.
Canada has seen eleven coalition governments.
The Great Coalition 1864 –- 1867
The Canadian Confederation was founded by the Great Coalition government which served in the United Province of Canada from June 22, 1864, to 1867. Its six Ontario ministers included three Liberals: George Brown, William McDougall, and William P. Howland. (Oliver Mowat was not in cabinet but was a delegate to the Quebec Conference.) It was clearly a success.
The Union Government 1917 — 1920
The Union Government of Canada (1917-20) was formed October 12, 1917, when Prime Minister Robert Borden formed a cabinet of twelve Conservatives, nine Liberals and Independents and one "Labour" member. In the December 1917 election the Conservatives ran as “Unionists” while the Liberal ran as “Liberal-Unionists.” It continued until July 1920 when Robert Borden retired.
Ontario’s Farmer-Labour Coalition government 1919 — 1923
In 1919 the United Farmers of Ontario elected 45 MLAs, and 13 Labour MLAs won seats. They formed a coalition government with a bare majority of the 111 seats. The cabinet included two Labour MLAs.
The federal Liberal Government of 1926 — 1930
In 1926 116 Liberal MPs were elected, a minority of the 245. A total of 38 others were elected: 26 Progressives or United Farmers, 4 Labour, and eight Liberal-Progressive MPs from Manitoba. The eight Liberal Progressives supported the Liberal government, making it in effect a majority government, and their leader Robert Forke (former leader of the Progressives from 1922 to 1926) was given a cabinet position, making it in effect a coalition government. Forke’s MPs continued to caucus as Liberal-Progressives and criticized some government positions.
The 1929 Saskatchewan election saw the incumbent Liberals win only 28 of the 64 seats. They met the House but were defeated by a Coalition of 24 Conservatives, five Progressives, and six Independents who formed a coalition cabinet which governed for five years.
The Saskatchewan Conservative-Progressive Coalition Government of 1929 — 1934
Manitoba Liberal-Progressive coalition 1932 – 1936
The Progressive Party of Manitoba was the governing party in Manitoba from 1922 to 1932. The Manitoba Liberal Party joined the government in early 1932, and three members of the party were brought into cabinet in a coalition with the Progressives ahead of the June 1932 provincial election. They formed not only a coalition but an electoral alliance to hold off a challenge from the Conservatives, winning under a variety of hybrid labels. The two parties had effectively become united by 1936, when they won re-election as a minority government with external support from Social Credit.
Ontario Liberal-Progressives 1934 — 1937
In the 1934 Ontario election the remaining Progressive MLAs led by former UFO cabinet minister Harry Nixon ran as Liberal-Progressives in an alliance with the Ontario Liberal Party led by former UFO member Mitch Hepburn. Four were elected and sat as Liberal—Progressives, technically in a coalition government with the Liberals, until 1937 when they ran as Liberals.
Manitoba unity government 1940 – 1948
In 1940, all Manitoba political parties joined a non-partisan administration formed to meet the province’s wartime demands. The CCF did not remain long when none of their proposals were accepted, but the unity government continued until 1948.
BC Liberal-Conservative coalition 1941 — 1951
In the 1941 election the Liberal government lost its majority, winning only 7 more seats than the CCF. They formed a coalition government with the Conservatives which lasted until it collapsed in 1951. Rather than forming an electoral alliance, they adopted the preferential ballot, with the objective of supporting each other against the CCF. The voters surprised them, when the 1952 election gave unexpected power to the BC Social Credit party (nominally led by a federal MP from Alberta) which soon abolished the preferential ballot.
NDP-Liberal Democrat coalition in Manitoba 1969 — 1971
In Manitoba’s 1969 election, the Progressive Conservative government dropped to only 22 MLAs, against 28 NDP MLAs, but the seven other MLAs held the balance of power. A plan for an everyone-but-NDP coalition, including five Liberals, one Social Credit, and one independent former PC, was about to be put into action when Liberal MLA Laurent Desjardins refused to join with the Tories, left the Liberal caucus, sat as a Liberal Democrat, and joined Ed Schreyer’s government as a Liberal Democrat, making it a coalition government until, in 1971, he joined the NDP, and the government served a full term in office, re-elected in 1973.
NDP-Liberal coalition in Saskatchewan, 1999 — 2003
In the 1999 Saskatchewan election NDP Premier Roy Romanow lost his majority. The three-member Liberal caucus joined a coalition, with cabinet seats, which lasted a full term.
Six stable minority governments
Six Liberal minority governments were able to govern with the support of the third parties.
Liberal Canadian government 1921 — 1925
The King minority government's ability to retain the confidence of the House from 1921 to 1925 depended partly on the strong anti-tariff policy favoured by the Progressive Party.
Pearson’s two governments 1963 — 1965 and 1965 — 1968
The minority governments of 1963–65 and 1965–68 won over the NDP with legislation that included a considerable expansion of social programs: universal health care, the Canada Pension Plan, the Canada Assistance Plan, and the Canada Student Loans Plan.
Pierre Trudeau’s government 1972 — 1974
The minority government of 1972–74 obtained NDP support by enacting, or by committing itself to enact, regulation of election expenses and the establishment of Petro-Canada and the Foreign Investment Review Agency.
Ontario Liberal—NDP Accord 1985 — 1987
In Ontario, the Liberals governed from 1985 to 1987 under an explicit written Accord with the NDP.
Paul Martin’s government 2004 — 2006
The minority government of Paul Martin (2004–06) governed with the support of the NDP when it amended its proposed budget to increase spending on social programs and defer tax cuts for large corporations.