What does objective mean? Objective means a mind-independent reality. That is, an objective feature of the universe is something that does not rely on my own – or anyone else’s – personal beliefs or feelings on the matter.
For example, gravity is an objective feature of the universe. It doesn’t matter how much I believe that I can fly, or how passionately I feel about it, when I leap unaided off the to of the building, I will come down. That is an objective fact. The claim that “the world is round” is an objective claim, and would be true even if everyone thought the world was flat. Similarly, If I were standing on a main highway, and you saw a truck speeding towards me, you would perhaps yell out “Get off the road, a big truck is coming!” If I then turned to you and said, “That may be true for you, but its not true for me,” it doesn’t really matter what I think, as the truck is an objective feature of the universe, unless circumstances change, I’ll soon be paste on the road.
So what is meant by objective moral virtues and duties is this: That it is bad and wrong to kill Jews and homosexuals, and even if Hitler had won the war, and succeeded in killing off or brainwashing all his opposition so that the whole world believed it was right, it would still be wrong. No matter what you personally believed about the matter, it would be wrong in that objective sense. Likewise, there are some things that are genuinely good and right, like loving your neighbour as yourself, caring for people who are suffering, generosity to those who are in need, and justice for the down-trodden, and these are all true in the objective sense.
Subjective, is precisely the opposite of objective. That is subjective belief relies on the individual. It is mind-dependant. For example, the statement “I am a man,” is an objective fact. The statement “I am here,” is a subjective fact as it’s truth relies on my own perspective. When morality is subjective, moral values and duties like “you should treat people with dignity and respect” become simply preferences of taste, equivalent to “I like chocolate over vanilla,” or “I hate television ads.”
It is clear then that subjectivism is an inadequate ethical system, not only practically but in truth as well. But that is for another time.