I made a claim that ethics are completely subjective; that there is no one correct answer to a question in the form of:
Is insert activity or behaviour here ethical or not?
It was suggested that I try that claim here. So, are ethics subjective?
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Philosophy is the human implementation of the "garbage in - garbage out" principle which in this situation means that with differently chosen "input" (starting premises or axioms, maybe also some nontraditional logic) you can get different "output" (ethics).
Not so short answer
In addition to the short answer it's interesting to know how humans manage to live in such relative peace and even in something what can be called an agreement about many ethical questions. That is so because we are similar (thanks to biology and sociology).
We can found the idea of natural similarity in many forms and times in the history of philosophy.
So what does philosophy do with this similarity? It uses conceptual analysis to dissect and clarify notions of morality (sometimes hoping to give a definite answer about what's good and bad), which, if used to reach the one true definition of morality, is the same as trying to make compromises between many subjective ideas - which is difficult to do also because of emotion-influenced motivated reasoning.
My first try to answer question here. Be nice and tear it apart!
What you're asking is a question about Metaethics. See this SEP article.
The position you're taking is some form of non-factivism or anti-realism. As stated, your view is ambiguous over VERY many possibilities.
Here is the entry on Moral Anti-Realism.
As you're reading through that article you can look at some of the related entries like Moral Relativism.
Depending on how you state your position, it may be a VERY unpopular one that almost no academic philosopher defends. For instance, the opening line of the Moral Relativism entry is as follows:
I might also add that these sorts of relativist/subjectivist views are very popular among undergrads without much philosophical training. Most Intro Ethics courses treat these topics in the beginning to disabuse students of the naive formulation of these views. You might be interested (if you are a college student) in taking a class in ethics (especially one with a section that covers metaethics) to become better acquainted with the philosophical landscape with respect to ethics.
Without more information you can't get a better answer to your question. I'd suggest reading through some of these articles and coming back with a more specific question.