Nowadays moral ethics are considered relative. Relative to culture, relative to the needs of a person, relative to circumstances and relative to what one assumes is right or wrong. Everyone has a different perspective on what is true; a person might believe that ‘x’ is true while another may not. The same concept applies to ethics, one person might say killing animals for food is correct and another might say it is incorrect as we can survive on natural food. So each person has a different estimation on making truth claims about ethics, the opinion depends on what is right or wrong and what is ethical and what is not.
Social relativism lessens ethics to sociology: what is right is whatever a particular society says is right. Radical relativism reduces it to a matter of taste: what is right is whatever the person believes and feels. And this is not just an academic challenge. If there is no truth in ethics, then parents are also left in a discontented state of trying to persuade their children that they ought, or ought not, to act in certain ways because to do, or not to do so, matches to the desires of others in that society or the parents themselves. However, if there is no purpose in “right” to back up this caution, there can be no justifiable fault, just as there can be no convincing answer to the question of why youth ought to put back to the wishes of others, including their parents, at the expense of their own. Truth is so fundamental to the sense of our life, that it can be argued that anyone who claims that there is no truth, i.e., not even truths about the physical world, is being duplicitous. The fact that such individuals are alive to make such claims shows that they have depended most of their behavior on what they have correctly believed to be true, e.g., that certain items nourish, while others poison.
From a more esoteric point of view, it is important to note that if there is no truth in ethics, there can be no authentic ethical philosophical enquiry either. Why else would philosophical inquiry be perceived to have advantage except on the assumption that the inquiry, if productive, moves us toward truth? The claim with the assertion that such inquiry is fruitful because it gives us a more complete understanding, or a more comprehensive viewpoint.
Many scientists talk about claims being true, e.g., it is true that heparin increases the clotting time of blood. Karl Popper pointed out; science does not progress on the backs of truths, but rather, on the backs of falsifications. A good scientist does not attempt to prove his claim to be true. He tries and proves his theory false. He starts with the illogical hypothesis: If theory X is not true, then Y should not happen. Then, if Y does happen, that shows that it is not the case that theory X is not true. In other words he, is to examine as much evidence as possible, in a manner that is as precise, and as objective as possible, and only after he has failed to prove his theory...