本研究探討廠商考量企業社會責任後，在獨占市場和外國廠商來本國直接投資兩種環境下，將會如何影響本國政府制訂最適污染稅。當市場由本國廠商獨占時，本國廠商越重視企業社會責任，本國政府制訂的污染稅越低。但開放外國廠商來本國直接投資的環境下，本國廠商越重視企業社會責任，本國政府將課徵越高的污染稅。 當本國政府面對本國及外國廠商不同的企業社會責任重視程度，將會影響其污染稅決策。結果顯示只要市場規模夠大，本國政府便會開放外國廠商來本國設廠投資，且課徵的污染稅為外人直接投資下的最適污染稅；市場規模不大的情況下，本國與外國廠商重視企業社會責任程度的不同將會造成多種結果，例如當本國廠商越重視企業社會責任，本國政府就會傾向開放外國廠商前來本國直接投資，但當外國廠商越重視企業社會責任，其自身能夠承受的污染稅降低，本國政府只好制訂禁止性污染稅。唯有當本國廠商不重視企業社會責任、而外國廠商較重視企業社會責任，也就是兩者程度差異很大的時候，本國政府才能設定一污染稅使本國廠商獨占。 ;This study discusses about how the firms who take corporate social responsibility into account can affect government’s optimal decision of pollution tax. There will be two environments to be analyzed, namely in the monopoly and foreign direct investment. In monopoly market, the more CSR the domestic firm is aware of, the lower the optimal pollution tax is. However, when foreign firm is allowed to invest directly in domestic country, the result is opposite. Our results show that if the market scale is large enough, the government tends to open the market, and agrees foreign firm to do FDI; but if the market scale is not large, then the firm of different level concern of CSR will lead to different results. For instance, when domestic firm starts to emphasize more on CSR, the local government tends to open the market for FDI. Nevertheless, the foreign firm cannot afford the pollution tax when it gets too high. Thus, the government will have no choice but to set the prohibition tax, then the domestic firm monopolize the market. Only when the domestic firm shows less concern about CSR, with the foreign firm highly concerning CSR, and the difference between their awareness is big enough, then the government can set a pollution tax which makes domestic firm monopolize the market.
