How much of a life is it, if twenty years are spent in jail?
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It's spring outside, my dear wife, spring.
Outside on the plain, suddenly the smell
of fresh earth, birds singing, etc.
It's spring, my dear wife,
the plain outside sparkles...
And <a href="http://www.cs.rpi.edu/~sibel/poetry/poems/nazim_hikmet/english/letters_from_a_man_in_solitary">inside</a> the bed comes alive with bugs,
the water jug no longer freezes,
and in the morning sun floods the concrete...
-- <A href="http://www.cs.rpi.edu/~sibel/poetry/poems/nazim_hikmet/_About/About2.html">Nazim Hikmet</a>
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If the options are "kill bad people with the risk of killing an innocent" or "don't kill people because you might kill an innocent person", it seems the obvious third option is "figure out more conclusively who is or isn't guilty".