Cohabitation in is a system of divided government that occurs in semi-presidential systems, such as France, when the President is from a different political party than the majority of the members of parliament. It occurs because such a system forces the president to name a premier (prime minister) that will be acceptable to the majority party within parliament. Thus, cohabitation occurs because of the duality of the executive: an independently elected President and a prime minister who must be acceptable both to this president and to the legislature.
The constitution of Finland, as written after independence, was originally similar to the French system. It included explicit provisions that the President focuses on national security and international relations. The arrangement was a compromise between monarchists and parliamentarists. In essence, a strong presidency was adopted instead of a constitutional monarchy. The new constitution of 2000 reduced the power of the President by transferring the power to choose a Prime Minister to the parliament. Cohabitation has occurred frequently, as Finland has multiple powerful parties which are not highly polarized between left and right, and also since the terms of a parliament are shorter (four years) than the presidential terms (six years). Theoretically, the President should remain strictly nonpartisan, and Presidents have usually formally renounced party membership while in office.
Cohabitation was a product of the French Fifth Republic, albeit an unintended one. This constitution brought together a president with potent executive powers and a prime minister, responsible before Parliament. The president's task was primarily to end deadlock and act decisively to avoid the stagnation prevalent under the French Fourth Republic; the prime minister, similarly, was to "direct the work of government", providing a strong leadership to the legislative branch and to help overcome partisan squabbles.