Final answer:
Callahan does not support voluntary euthanasia due to concerns about intentional killing, the sanctity of life, and the potential for abuse and the slippery slope.
Step-by-step explanation:
Callahan's opposition to voluntary euthanasia is rooted in several philosophical and ethical concerns. Firstly, he argues that active euthanasia is fundamentally wrong because it involves the intentional killing of another person, which goes against our moral principles. Secondly, Callahan emphasizes the importance of preserving the sanctity of life and believes that allowing voluntary euthanasia would undermine this value. Lastly, Callahan expresses concerns about the potential for abuse and the slippery slope that could occur if euthanasia were widely practiced.