an example of an established worker co-operative with a policy of pay parity. From the collective movement, one of the most successful ventures is probably Suma Wholefoods in Elland, West Yorkshire. Political philosophy of workers' cooperatives The advocacy of workplace democracy, especially with the fullest expression of worker self-management such as within workers' cooperatives, is rooted within several intellectual or political traditions: The alleviation of alienation in the workplace, especially in regard to Marxist thought The encouragement of participatory or direct democracy Radical but popular-democratic strategies for the overthrow of capitalism, for example, several strains of socialist and anarchist thought Autonomy and self-control, especially within anarchist thought Cooperating with other worker cooperatives Workers' cooperatives are also central to ideas of autonomism, distributism, mutualism, syndicalism, participatory economics, guild socialism, market socialism and libertarian socialism, among others. The idea of achieving economic democracy through worker ownership on a national scale has been argued by economist Tom Winters, who states that "building a cooperative economy is one small step on the journey to reclaiming the wealth we all collectively create." An economic model: the labor-managed firm Economists have modeled the worker cooperative as a firm in which labor hires capital, rather than capital hiring labor as in a conventional firm. The classic theoretical contributions of such a "labor managed firm" (LMF) model are due to Benjamin Ward and Jaroslav Vanek. In the neoclassical version, the objective of the LMF is to maximize not total profit, but rather income per worker. But such a scenario implies "perverse" behavior, such as laying off workers when output price rises so as to divide increased profits among fewer members. Evidence supporting such behavior is lacking, however; a review of the empirical economics literature is found in Bonin, Jones, and Putterman. But alternative behavioral models have been proposed. Peter Law examined LMFs that value employment and income. Nobel Laureate Amartya Sen examined pay according to work and according to need. Nobel Laureate James Meade examined behavior of an "inegalitarian" LMF. Worker cooperatives tend to have a more compressed wage distribution, which can potentially turn off high-ability workers, potentially causing the cooperative to suffer a "brain drain" as they leave to seek higher wages elsewhere, though this effect is less of an issue in a cooperative with a less compressed wage distribution. Hiring managers from capitalist firms can be very difficult because of the lower wages. Generally, the evidence