一個反對雙果律的新案例：高架電車

A new case against the doctrine of double effect: elevated tram

根據「雙果律」，行為者的行為意圖本身對行為的道德許可性有決定性影響。具體來說，當行為同時有好結果與壞結果時，壞結果不能是行為者所意圖的。意思是說，如果壞結果是行為者所意圖的，則此行為在道德上不被許可。雙果律有其案例上的吸引力，當然，也面臨反例的挑戰。在面臨挑戰時，雙果律者通常透過修改理論來避免反例。一種常見的理論修改方案，是主張雙果律所規範之意圖非行為者「真實意圖」，而是「可能意圖」。另一種常見做法，是區分「意圖結果」與「原因結果」。這些修改方案可以解決目前檯面上的主要反例，而本文則試圖提出另一種反對雙果律的新案例，我稱之為「高架電車案例」，我將說明前述修改方案都無法成功回應此案例，因此，在能夠恰當回應此反例前，雙果律尚不是令人滿意的道德許可性理論。

According to the doctrine of double effect (DDE, henceforth), the intention of an action is a major factor of its moral permissibility. Consider an action producing a good effect and a bad effect, DDE holds that one must not aim at the bad effect to realize the good one. In other words, it is morally impermissible for one to aim at a bad effect, even just to good ends. DDE is attractive in many cases, but still upset by some counterexamples. Proponents of DDE propose different modifications to avoid counterexamples. Among them, one prominent account holds that it is the possible intention rather than the actual one that DDE is about. Another popular way to respond is to propose a distinction between“intend to x”and“because of x”. Both strategies seem to be successful. However, I argue that these proposals are in difficulties with a new kind of counterexample, elevated tram. Consequently, DDE is no longer satisfactory until it addresses this issue.