解題
**Introduction:** A monopsony occurs when there is a single dominant buyer of labour in a market, giving the employer significant wage-setting power. In a perfectly competitive labour market, wages and employment are determined by the intersection of labour demand (the Marginal Revenue Product of Labour, \(MRP_L\)) and labour supply (Average Cost of Labour, \(AC_L\)). A monopsonist, however, faces an upward-sloping labour supply curve, meaning the Marginal Cost of Labour (\(MC_L\)) lies above \(AC_L\). To maximize profits, the monopsonist equates \(MC_L\) to \(MRP_L\), resulting in a lower wage (\(W_m\)) and a lower employment level (\(E_m\)) than the competitive equilibrium (\(W_c\), \(E_c\)). This leads to the exploitation of labour and a deadweight loss of economic welfare. Government intervention is often proposed to correct this market failure. **Arguments for Intervention:** One primary method of intervention is the implementation of a national minimum wage (NMW) or a legally binding wage floor. If the government sets a minimum wage (\(W_{min}\)) above the monopsony wage \(W_m\) but equal to or below the competitive wage \(W_c\), it alters the firm's marginal cost of labour. The marginal cost of labour becomes perfectly elastic (horizontal) at the minimum wage level up to the supply curve. Consequently, the firm no longer has an incentive to restrict employment to keep wages down. Under these conditions, the minimum wage can simultaneously increase wages and increase the level of employment toward the competitive level \(E_c\). This reduces inequality, increases the incentive to work, and eliminates the allocative inefficiency associated with monopsony. Alternatively, the government can intervene by encouraging trade union representation or breaking up dominant employers to foster competition. Strong trade unions can bargain for collective wage agreements, effectively acting as a bilateral monopoly and pushing wages and employment closer to competitive levels. **Arguments against Intervention (and Potential Government Failure):** However, intervention is not guaranteed to be beneficial. First, there is the risk of government failure due to information failure. If the government sets the minimum wage too high (above the competitive wage \(W_c\)), the labour market will transition to a situation of excess supply, leading to classical unemployment as firms reduce hiring. Second, some monopsonies are state-owned or state-funded, such as the National Health Service (NHS) in the UK employing medical professionals. In this case, the government uses its monopsony power to keep wage bills low, which keeps taxpayer costs down and allows for greater public service provision. Forcing wages up in public monopsonies without a corresponding increase in taxation or productivity could lead to budget deficits or cuts to public services, reducing overall social welfare. Third, policy measures like breaking up a monopsonist might destroy economies of scale, particularly if the employer is a natural monopoly in its product market, resulting in higher prices for consumers. **Evaluation and Conclusion:** In conclusion, government intervention is not *always* beneficial, but its success depends heavily on several factors. The first is the accuracy of information available to policymakers; setting price or wage controls requires precise knowledge of the labour supply elasticity and \(MRP_L\), which is difficult to measure in practice. Second, the nature of the industry matters; correcting private-sector monopsony exploitation generally improves welfare, whereas intervening in public-sector monopsonies involves a complex trade-off between workers' wages and fiscal responsibility. Third, the choice of policy tool is crucial; supply-side policies that improve labour mobility (such as retraining schemes or housing subsidies to reduce geographical immobility) may be more sustainable long-term solutions than blunt wage controls, as they directly address the root causes of monopsony power rather than just its symptoms.
評分準則
**Mark Breakdown (Total 25 Marks):** *Level 5 (21–25 marks):* Candidates demonstrate excellent, highly focused economic analysis. They present a clear, coherent, and balanced argument using precise economic terminology, including detailed references to monopsony diagrams (describing the relationship between \(MC_L\), \(AC_L\), and \(MRP_L\)). Evaluation is robust, critical, and well-integrated, culminating in a reasoned conclusion that directly addresses the word 'always'. *Level 4 (16–20 marks):* Candidates provide good economic analysis of how monopsonists restrict employment and wages, and how government interventions (like minimum wages or unions) correct this. Evaluation is present and structured but may lack the depth or completeness required for Level 5. There may be minor slips in diagrammatic descriptions. *Level 3 (11–15 marks):* Candidates show a reasonable understanding of monopsony power and at least one form of intervention. Analysis is present but may be incomplete or lack a clear chain of reasoning (e.g., failing to explain why marginal cost is above average cost). Evaluation is limited, weak, or unbalanced. *Level 2 (6–10 marks):* The response is largely descriptive with some basic understanding of labour markets, monopsony, or government intervention. Arguments are undeveloped, and there is little to no evaluation. *Level 1 (1–5 marks):* Very weak response showing minimal economic knowledge. Contains major errors and lacks focus on the question. **Key Content to look for:** *Analytical points:* Definition of monopsony; diagrammatic/logical analysis of how monopsony leads to underemployment and underpayment relative to perfectly competitive outcomes; analysis of minimum wage as a counter-strategy (reversal of employment trade-off); analysis of alternative policies (unionization, anti-trust regulation, training to reduce immobility). *Evaluative points:* Risk of government failure (setting wage floor too high causing unemployment); public sector vs. private sector monopsony differences; cost/benefit trade-offs of different interventions; elasticity of supply and demand for labour; long-term vs. short-term impacts. *Accept:* Accurate alternative policies like reducing search costs or improving geographical mobility. *Reject:* Analysis purely focused on product market monopoly without linking it to labour market monopsony.