Positive economics claims to study what is. However, what is also is subject to cultural and value based interpretations. Why, then, have such a largely exclusive and tall claim?
Major difference, between positive economics and normative economics is that positive economics analyses in a scientific manner, the cause n effect b/w variables n provides actual results (e. g., what it is) without providing optimum solution, e. g., what should be.
Here what should be is based on value judgement (that is further based on certain beliefs), such as:
ethical
political
philosophical
religion etc. not on scientific logic or laws that is known as normative economics
Yes indeed it is depending on where one stands in the economic-scheme-of-things. A better nomenclature would be "positivist economics" or "neoclassical economics", so that it would have the same connotation as positivism in the philosophy of science. Or the physics-envy side of economics, economics aspiring to be considered a science. Another way to think of it is to consider both positive and normative economics as part of a broader philosophy of economics. The positive-normative dichotomy is also rather outdated (though it comes in handy to refer to the objective and subjective side of field) given that there are at least nine schools of thought in economics as highlighted by Ha Joon-Chang in his book: Economics:the user's guide.