The sciences have established the equality of human beings, finding no inborn differences that are causal in different life outcomes, save for the case of genetic diseases. Everything else is developmental, from the womb outwards. The sciences have also established that humans essentially reproduce in groups. Despite the occasional hermit or the more common agoraphobic (overlapping groups?) therefore human nature in general must make concessions to living in groups. The individual who wishes to make normative moral arguments that should be taken seriously by others must therefore formulate them in those terms. He or she must argue as if any person could benefit by the norms proposed. As said before, he or she must argue from what must be, what cannot be and what can be as a foundation for an argument as to what ought to be.
There are of course those humans who reject the notion that they should obtain rational consent and seek to impose their personal norms by means other than persuasion, even though they themselves would not care to suffer this. Although they have no measurable superiority, they would claim it anyway. The sciences, as well as our own amour-propre, should lead us to reject this out of hand. And it should seem inevitable that we would scorn offenders for this insolence. The people who would steal moral superiority that isn't theirs are like thieves stealing property that isn't theirs. Neither party acknowledges that, if they want to have their rights, moral or property, acknowledged by others, the same obligation is on them. The others, which we generally include the reader, can imposes this obligation because it is a necessity and a truth. Most individuals confront the social incarnation of currently accepted morality as an externality, imposed upon us by an abstract collective entity. Their various subjective discontents often are due to personal desires to claim more than their objective right as equals in the social enterprise.
But the difficulty arises when the group authority to sanction (positively or negatively) those who violate the essential requirements of being part of the group is not rational. This is not a question of why a group authority must be normative. Human groups are necessary for human life. This is normative because the vast majority of people wish to live. And the few who don't wish to live can still exercise that right, despite official or informal disapproval. The question is not the normativity, but the necessity. It was once regarded as necessary that there be slavery; that democracy threatened the social order that made life possible; that women's sexuality be closely policed, and on an on in an hideous history of oppression.
Social science examining as objectively as possible the social life of humans provides the only basis for objective critique of the morality imposed by society. That is why philosophers, led by the infamous Karl Popper, seek to deny the authority of science to the social disciplines. Their demarcation problem is how to redefine science to exclude any objective basis to critical views. Ideas lost in the morass of philosophy pose no threat. (In principle, philosophy can aim to positively justify the current order, but in practice this effort ot synthesize a complete world view seems to be limited to brief, foundational epochs. In the Western tradition, ancient Greek philosophy and the Enlightenment sought the truth about reality, instead of valid arguments.)
In the natural sciences, usually there is a narrowly practical test at some point. It may be experiment but certainly the overal progress of the natural sciences interacts with technology, giving it a straightforwardly empirical bent. The historical sciences are commonly more difficult for philosophers of science seeking to muzzle its voice, but the seamless connection to experiment of some sort provides an escape hatch. The straightforwardly empirical but nonexperimental (as in controlled experiment, the default ideal in every case I know of,) sciences like taxonomy and cartography in all its many forms are simply omitted from consideration. Apparently the feeling is that these are too base, too lacking in verbal forms that can be analogized to mathematical theorems, to be worth remembering.
It is the historical sciences of course that are most likely to confront the irrational justifications for social authority, which equally of course is mostly likely religion. Geology in the US confronts Genesis. Biology confronts not just Genesis but(religious) vanity, which forbids kinship to animals rather than angels. Cosmology confronts Genesis and wishes for kindly Providence. Quantum mechanics fosters cosmic woo, as near as I can tell, precisely because the difficult foundational questions allow those so inclined to redress old ideas of Providence and/or Spirit.
The peculiar demarcations of science intended to keep out social critique often lead to complications in defending the natural sciences against such intrusions. Predictionism and falsificationism falsely frame the questions of the nature of scientific explanation and empirical verification. Practicing scientists usually bow to the nature of the academic enterprise and accept the philosophical foundations of antirealism. Then they console their consciences by surreptitiously smuggling in realist views, hoping to have the best of both worlds, the rewards of subservience to the powers that be and the rewards of the free inquirer.
The real demarcation problem, almost never addressed by philosophers of science (Bunge is an exception that I know of,) is demarcating good social science from old, exploded ideas artificially revived to support the prevailing order; incipient sciences imperfectly conceptualized and/or insufficiently empirically based; dead ends of incoherent ideas, false facts (the greatest enemy of science!) or monastic communities sealed off from the rest of science; trivia masquerading as academic credit and fraud, simple or complex. I see that this worthy goal is far beyond my means.
The greatest reason of course is that critique of false facts involves a detailed understanding. This must be done in each scientific field by and large. In the social science unfortunately, the balkanization is such that some fields, such as evolutionary psychology or parapsychology, can insulate themselves from the rest of science. Academic courtesies then cover a multitude of sins. If a David Deutsch writes a popular science book with some good physics and some deranged social science, it is impolite to say so. If a Steven Pinker writes a whole series of books, each marred by some gross error, it is impolite to say so. The regular person, with no access to the literature, is pretty helpless. No, it is not true that everything is on the internet.
There is one obvious red flag. If social science purports to explain just how human nature or cosmic nature justifies the current state of affairs, particularly an imaginary state of affairs where this is an excellent social order, take warning. Indeed, if the purported social science takes the notion of human nature too blithely, take warning. If the purported social science ascribes ideas an independent influence, take warning. If the purported social science argues that randomness is the dominant factor in humanity, take warning. If the purported social science argues that there is a muliplicity of causal factors but refuses to attempt to rank them in importance, take warning. If the purported social science emphasizes experiments over the facts of history and anthropology, take warning. If the purported social science makes claims about history and other societies and economies without trying to outline a causal sequence, take warning. Most of all, if any purported social science tries to base itself on history or economics without proper comparisons, take warning. This is the social science equivalent of doing an uncontrolled experiment!