有些人認為積極的安樂死應該被永遠禁止，消極的安樂死則偶爾 可以被允許，因為前者是一個殺人的動作，後者只是放任一個人死 亡。然而，有些人主張一個行動是一個殺人的行動、或是一個任其死 亡的行動，這個差異不會影響我們的道德判斷，因此殺人與任其死亡 之區分不能用來作為支持消極安樂死、反對積極安樂死的理由。要辯 護殺人與任其死亡在道德上是等值的，其中一個方法是使用對照的策 略，發展對照的例子，從而導出等值主張。透過對照的策略所獲得的 等值主張，幾乎不建立在任何理論上，而是訴諸我們的直覺。本文藉 由戴維森的行動的因果理論，為等值主張提供理論上的根據，並以此 回應反對意見，辯護等值主張。

That killing is morally worse than letting die has been used as a reason for the view that passive euthanasia is sometimes morally permissible while active euthanasia should always be forbidden. Some argue that the distinction between killing and letting die has no moral significance, and so it is not a reason for passive euthanasia and against active euthanasia. There are various ways to defend the moral equivalence of killing and letting die. One of them is to develop contrast cases and derive an equivalence thesis. The formation of such a judgment is not based on any moral theory but rather appeals to our intuition. This paper seeks to defend the equivalence thesis. It uses Donald Davidson’s causal theory of action to find a ground to support the thesis, and responds to objections from a Davidsonian perspective.