Individuals? Or members of society?
Infractions of personal liberty can be justified when they improve the welfare of individuals on the whole, even when they on occasion diminish the welfare and freedoms of particular people. The argument against assisted suicide on these grounds is not that your doing it directly harms others, but that your having the right to do it requires changing the social ecology in such a way as to diminish the ability of all individuals to thrive in it.
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