The death penalty is meant as a strong deterrence.
Put it this way. When we are taught criminal law, the most
simplistic explanation for the purpose of criminal law is this: The
purpose of criminal law is to preserve and protect law-abiding
citizens and as a tool of social control. Penalties give a
practical incentive to obey the law, and censure those who still
choose to break the law.
We do lock people up in hopes of rehabilitation. But realistically,
its more for retribution. The other two reasons would be expiation
and incapacitation. We are not as noble as we hope to be. And
really, you can't really rehabilitate criminals by locking them up
together. You'll more likely breed smarter criminals when they
share tips on how to commit crimes.
As for the death penalty, the only thing I feel is unfair in
Singapore is that such cases are heard by only one judge. I
personally believe that the jury system is best for such cases.
It's been found that juries are typically much better at deciding
questions fo fact, leaving the judge free to contend with questions
of law. Also, think about it. 12 heads are better than 1. There
will be more experience and juries allow community input into what
we believe to be right or wrong.
However, in Singapore, that's not going to happen. The next best
thing we can have is to have a panel of 3 judges presiding with a
majority verdict needed for conviction. While people may complain
about the demands on the court system, I think it is only fair
given the severity of punishment. Also, once the sentence is
carried out, there is lesser by way of compensation if it were a
wrongful conviction. I personally believe it is rather frightening
that just one person will decide your guilt.