After a discussion with an acquaintance regarding the morality of smoking marijuana, I got to thinking. This acquaintance is rather on the religious side and it was very apparent that she derived all justification for her moral stances directly from scripture and religious authority. I, on the other hand, analyze the morality of specific issues based on their impacts on individual people, society, etc.
So, I was wondering how you justify the morality or immorality of specific acts. Some of my examples:
Murder: This is wrong because it clearly eliminates another person’s basic human rights–life, liberty, and the pursuit of happiness, to quote a famous document. Each person should have the right to self-perpetuation.
Heroin, Meth, Cocaine, etc: While I make no judgments what you can or cannot do with your own body, the use/sale/manufacture of these substances clearly have negative effects on society. Users are very likely to commit crime, including theft and assault, in order to get more of the substance.
Same-sex marriage: Clearly moral, in my view, because each person should be able to pursue their happiness in whatever fashion they please so long as it does not infringe on another’s right to do so. SSM is a private affirmation of love, affection, and happiness.
A note: this question is for everyone, including those that may identify as religious, but I am interested in rational moral justification. Also, this question is not meant to be GD material; no debating whether X is moral or immoral.