Whenever you engage in high level discussions, many of the points made by you and your opponents are founded on claims that some things are "relevant" to other things. Those who engage in arguments usually make it sounds like "relevance" is an objective concept, almost algorithmic. They often suggest that what is relevant can be clearly determined by necessary and sufficient conditions. They make it sound as though all reasonable people would come to the same conclusions about what is (and is not) relevant, if only they pondered long enough. It is my position there is no meaningful simple definition of "relevance" in any real world field (the concept works in math and logic).
This is how I used to think many years ago. Now, however, I am convinced that what is "relevant" is always a matter of the emotional tuning of the person claiming relevance. No, it's not a completely subjective measure, given that we all inhabit human bodies and thus have a shared basis for our observations. But neither is it an objective measure, applying to all people at all times.
What is relevant to morality? Tradition, upbringing, what the powers-that-be decree, logic, distribution of resources, the Bible, the Koran, whatever comes clear through personal meditation, patriotism, sustainability, or what respects personal liberties? We humans are tuned in a million different ways. Perhaps if we were all tuned the same, we could speak of some objective concept of relevance, but that is not the case. Also, add to the nuance of the word "relevant" that humans are incredibly symbolic, meaning that they have the power and imagination to make anything at all meaningful to anything else. We can even turn meaning upside down, in Orwellian fashion. What is "relevant"? What do you want to be relevant?
My views are quite sympathetic to notion (of George Lakoff and Mark Johnson) of experientialism: Namely, that the verbal expression of the facts of life is, at bottom, indeterminate despite our most persistent attempts to capture them with language (which often border on the heroic). Most people nevertheless have faith in “objectivity,” (e.g., that "relevance" refers to necessary and sufficient conditions). People cling to objectivism because, perceiving no middle ground, they fear that the only alternative is a free fall to nihilism. They cling not to just any “objectivity,” of course, but their own version of objectivity. Experientialism makes a strong case in showing the “objective” use of language to be a myth: there is no such thing as abstract and disembodied thought. Truly “objective” thought would require the impossible: a “logical propositional trajectory from principle to concrete application.”
Under the cover of “objectivism,” however, the widely-shared meanings of concepts have always been grounded in and constrained by our widely-shared biological, cognitive, social, and linguistic interactions. These interactions, which constitute our bodily existences, extend imaginatively and metaphorically to give what substance there is to high-level concepts. “Objectivity,” as used in the context of legal decision-making (and elsewhere), can exist only to the extent that these interactions are widely shared. It must not be overlooked that such interactions are widely shared, enabling extensive meaningful communication, even among people of divergent languages and cultures. No radical deconstruction of language is being suggested.
I am always on high alert when someone makes an argument, indicating that something is "relevant," much less "highly relevant." Whenever such a claim occurs, it is time to puncture the bubble and force the participants to put their emotional baggage on the table, as best they can. There is no other way to have a meaningful conversation regarding contentious topics.