"The relativist fallacy, also known as the subjectivist fallacy, is a formal fallacy committed, roughly speaking, when one person claims that something may be true for one person but not true for someone else. The fallacy is supposed to rest on the law of non-contradiction. The fallacy, it is said, applies only to objective facts, or what are alleged to be objective facts, rather than to facts about personal tastes or subjective experiences, and only to facts regarded in the same sense and at the same time ".
en.wikipedia.org/wiki/Relativist_fallacy
I've a doubt that how can I know what matters are objective matters and what matters are subjective. Is there any means to know, if it's objective or subjective. How can we be so sure that we know somethings that we think are objective but they're really objective?
And many people use the term 'it is relative', when they like to say 'it is relative ! Is there any psychological/philosophical reason for this kind of description?