Laissez faire (imperative) is distinct from laisser faire (infinitive), which refers to a careless attitude in the application of a policy, implying a lack of consideration, or thought.
The laissez-faire school of thought, or libertarianism, holds a pure capitalist or free market view, that capitalism is best left to its own devices — that it will dispense with inefficiencies in a more deliberate and quick manner than any legislating body could. The basic idea is that less government interference makes for a better system.
Many historians see laissez-faire philosophy and policies as becoming predominant in the late 19th and early 20th century in the richer countries of Europe and North America. In practice, however, critics point to evidence that suggests that what was described as "laissez-faire" policy was simply pro-business policy, as with large subsidies for businesses to produce the railroads in the United States or the common use of tariffs by Republican presidents there. In this context, laissez-faire rhetoric was used to justify denial of similar subsidies to the poor and working classes.
For many, Laissez faire theories fell into disrepute because of their failure to allow governments to deal with managing the economy during World War I and their alleged failure to prevent The Great Depression. But some libertarians argue that by the time of the Great Depression, significant government economic regulation had already taken place in most major economies, as workers and employees in all industries organized themselves into trade unions to demand better living standards, as well as various checks and balances to the perceived "tyranny of laissez faire". Workers succeeded in obtaining minimum wage laws and a progressive income tax in some countries. International trade barriers were also in the policy pipeline (eg Smoot-Hawley Tariff in the USA). So the economies that suffered from the Depression were far from embracing the pure capitalist model or laissez faire. Some critics of laissez faire argue that the attainment of pure capitalism is impossible, for example since it is difficult to abolish labor unions or to deal with market failures without an active role for government.
Modern industrialised nations today are not typically representative of laissez-faire principles, as they usually involve significant amounts of government intervention in the economy. This intervention includes minimum wages, significant redistribution through tax and welfare programs, government ownership of businesses and regulation of market competition. However, many suggest that President Ronald Reagan of the United States and Prime Minister Margaret Thatcher of the United Kingdom followed a generally laissez-faire perspective.
In the wake of the rise of the USSR, laissez-faire economics assumed a stronger ideological edge, see e.g. Hayek). In the post-war era, where state regulation and involvement in the economy reached a peak, to no small extent as part of the Cold War, anti-statist schools of economic thinking enjoyed a surge of interest and support.