大经济面关税对GDP增长是负面的；一般关税是用来控制和保护一些国内窄的产业

In general, tariffs tend to negatively impact GDP growth.?Studies suggest that tariffs can lead to reduced domestic output, lower productivity, and potentially higher unemployment, even though they may have small effects on the trade balance.?Optimization theory, while not a specific, direct relationship, provides the framework for understanding why tariffs might lead to these outcomes by analyzing how they affect a country's terms of trade and overall welfare.?

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Elaboration:

• Negative Impact on GDP:

  Research indicates that tariff increases correlate with declines in both domestic output and productivity.?For example, one study estimated a 1.6% long-run impact on real GDP from a uniform tariff hike, with a larger potential impact from tariffs specifically targeting Chinese goods,?according to a Morningstar report.?

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• Unemployment and Inequality:

  Higher tariffs are often associated with increased unemployment and potentially higher income inequality.?

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• Trade Balance Effects:

  While tariffs can sometimes lead to a smaller trade deficit, studies show that the impact on the overall trade balance tends to be relatively small compared to the impacts on output and productivity.?

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• Optimization Theory:

  Optimization theory, in the context of tariffs, analyzes how a country can maximize its welfare given its trade relations with other countries.?A large economy, for instance, might choose to impose tariffs to improve its terms of trade (the ratio of its export prices to its import prices), potentially leading to a net gain in welfare.?However, this is a complex issue, and the optimal tariff level is influenced by various factors, including the responsiveness of other countries to retaliatory tariffs and the impact on domestic producers and consumers.?

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• Retaliation and Supply Chain Disruptions:

  A key consideration in the impact of tariffs is the potential for retaliatory measures by other countries.?Retaliation can disrupt supply chains and lead to reduced trade, further impacting GDP.?