Gerald MacCallum doesn’t think that negative and positive liberty are two distinct concepts. He argues instead that there’s only one concept and that it is a mistake to characterize freedom, as Berlin does, as either one of two “dyadic relations” – “freedom from” (negative liberty) and “freedom to” (positive liberty).
It’s hard to find someone who is against liberty, but it’s easy to find disagreement about what the term “liberty” means.
The philosopher G.E. Moore, writing in the early 20th century, criticizes the grounding of moral claims in non-moral observations, which Moore refers to as natural properties.
Ross was a Scottish philosopher who died in 1971. He is well-regarded in the academic institutions which makes it sensible that B and C encountered his seminal text. He attempted to make a sound ethical theory. That is, one that could assist in almost every ethical problem encountered.