One argument against free trade is the terms of trade—since an export subsidy worsens the terms, it has to be conceived as a negative one, a tax paid by foreigners. However, the optimum export tax is...

One argument against free trade is the terms of trade—since an export subsidy worsens the terms, it has to be conceived as a negative one, a tax paid by foreigners. However, the optimum export tax is one that maximizes national gain without harming export. How would it work in the case of a commodity exporting country like Indonesia?