I stopped reading the philosophy journals some years ago, so I'm not competent to comment on the views of our current crop of academic philosophers. However, I always thought that those who advocate for the social construction of reality are unlikely to have had much contact with it. Perhaps their parents didn't believe in corporal punishment; perhaps they didn't skin their knees enough when they were growing up; perhaps they never felt the fists of a bully. Whatever their story, their notion that they and you and I and the rest of our motley race inhabit a world that we've thought into being is, in my estimation, a Borgesian fantasy. Reality is not a movie, structured by the whims of a society of directors, and thinking it is is almost always a sign of derangement.
But that's just me...
All the best to you and yours, my friend...
"There is no objectivity or universality, there's only subjectivity and the psychological, which are conventional and variable: in other words, there is no external metaphysical basis for language and logic."
I am not the one to whom your question was addressed, but it is an interesting topic.
The problem in discussing it, or anything else, is that to discuss it we all have to use words. Now, it is not true that words mean nothing at all. They DO have meaning, but the meaning is not intrinsic. Certain sounds, like the sound one makes in a yawn, or a yelp of pain, or a baby's cry, actually do carry intrinsic meaning without words. But once we organize sounds into spoken words, and organize speech into written symbols (either phonetic or pictographic), to know what the symbols and sound patterns means requires education. Smiles are universal, as is the cry of a baby, but the word "I" is not universal (although there is universally a word to express the concept "I").
The problem is not that words are completely fluid and have no meaning. Rather, the problem is that words are fuzzy and do not have precise boundaries. The identical problem arises in religion, especially when religion is based on a specific written text (e.g. the Bible) as opposed to the decisions of hierarchical authority. Words mean things, and the text means things, but there is a range of things that the text COULD mean. PERHAPS it means only one specific thing; PERHAPS it means all of those possible interpretations; or PERHAPS it means some, but not others (or perhaps the text isn't inspired at all). It isn't true that the words are totally devoid of meaning. Yes, we've assigned a meaning to a speech pattern, but there really is a meaning that was assigned. There really is such a thing as a "father" and a "mother", and each is necessary to generate a new child. That does not mean that the "father" and "mother" have to have all, or any, of the features we culturally associate with fatherhood and motherhood...it means that sperm has to come from a male organ and meet with an egg from a female organ, and grow in a female womb (biologically speaking). However, there are those who will VOCIFEROUSLY argue that "father" and "mother" mean a hell of a lot more than just the narrow biological definition. And those people would be RIGHT, too.
Words have fuzzy edges.
Another place we see this is in the law. Look at the fights on Free Republic over the meaning of the Constitution! It's written in English words and is comprehensible, but the words themselves are not digital. They're "analog". They have fuzzy edges. It isn't STRETCHING the meaning of a word to use it in one of its regular senses, even when that use differs from what someone else passionately believes the word means.
Now, in religion, the problem of verbal authority is resolved by appeal to a human hierarchy to interpret the text. This is the "Catholic" approach, embraced by many but strongly and loudly rejected by some. Note that the Catholic approach makes the words not as important as the power that interprets them.
Likewise, in law, the "Catholic approach" is to say that the words COULD mean a lot of things, but for our purposes they DO mean what the hierarchical authority charged with interpreting them (the Supreme Court) SAYS they mean. There are those who will vociferously denounce this as judicial activism.
It's even more complicated than that, because there is usually a fuzzy inconsistency even in the approach to the hierarchical authority's power to interpret. Even THAT is said to be LIMITED by the text.
So, yes, there IS a circularity to this. We will find in a moment that there is pervasive circularity in scientific definitions on which the whole theoretical structure of physics stands too. But it is not, as the Analytical School would have it, that words are radically indeterminate in meaning, and that therefore everything is completely subjective and psychological. The most solipsistic subjectivist bangs his head if he walks into a tree and runs for the toilet when he's got the runs, and no amount of LINGUISTIC deconstruction will move the tree out of the way or quieten his disturbed bowels.
Nature has a material component to it as well, which is certainly real. That our words cannot perfectly overlay this reality with mathematical precision is true. That doesn't make the words useless. And it doesn't make nature go away. It is absolutely no different with law or social usage either. "Mother" and "father" may have biological components, but those biological components INCLUDE a sociological component (as in, without PARENTING, no child grows to reproduce, and thus "sperm donor" and "egg" donor, as biological descriptors, capture only a PART of what the word "mother" and "father" mean, and it is by no means satisfactory, or accurate, to try and simply LIMIT the meaning of the words "mother" and "father" to a PARTICULAR necessary instance of biology when there are subsequent vital instances of biology as well.
The real problem is that mathematics, as a language, APPEARS to be very precise (it isn't: probability is not precise, it's a guess regarding a random result which isn't predetermined), and is used extensively in science. This gives natural science a veneer of discrete digital exactitude which actual nature does not have. When you WRITE ABOUT chemical equations, everything is exact on paper, in formula. When you actually DO chemical composition in the laboratory, you only get a percentage yield. There are reactions that simply fail to come off, even though they ought to. There are myriad reasons, but the point is that the most rigorous formula that works on the theory only works up to a point in practice. It doesn't matter what the sphere of natural science is: the real world isn't digital and doesn't behave digitally, but the world of the classroom, of theory and tests DOES.
So, we all walk around (all of us who are scientifically educated or who even have a passing familiarity with the natural science) learning very rigid, sharp, precise theories...which is to say strings of words. But ACTUAL NATURE is really more like the imprecision of the words we use for everything else. Our theories express reality, but they contain an exactitude that exceeds the parameters of nature. Usually we think it's the opposite, but that's our theories getting on top of us, and us tending to think in terms of the perfection of words (including math strings), as opposed to thinking in terms of the fuzzier-edged analog reality of nature, including human nature.
When you go into natural science EXPECTING the world to be precise and discover that it's not, this can be viewed by some who take the theories as theology to mean a loss of faith in science. But that would be no more appropriate than to lose faith in fatherhood because there are fathers who beat their kids and walk away without providing parental support. Nor would it be appropriate, reversing the telescope, to assert that BECAUSE a man is a father, than THEREFORE he certainly nurtures his children. The Analytical School's approach seems to go so far as to say that the concept of "fatherhood" is SO fuzzy and imprecise that there REALLY IS NO SUCH THING, except insofar as we reify it with words. But that is clearly untrue. There remains the "sperm donor" function, and there remains the general reality that if men do not protect women and children, they'll be killed by nature, including other humans (the police and government structures as "General fatherhood").
I fear this is becoming a rambling discourse, which is unfortunate because there really is a point to be made in all of that.
So let me sort of restart and use a direct example from the natural sciences.
Gravity.
What is gravity?
If you look it up, you will find it to be an attractive property associated with mass.
Ok, then what's mass? It's something that occupies space and has gravity.
What's space? A real dimension capable of holding mass.
Delve down a few more layers, and you'll get "energy" in there.
And you will discover that you are running a round robin of definitions: gravity is caused by mass. Mass is identified by causing gravity.
Now, the Analytical School would throw up its hands at this point and say "See, there's no THERE there! It's not reality! It's just concepts! And fuzzy ones at that."
Well, yes, the concepts actually ARE fuzzy, and imprecise, and not digital at all.
But if you step out of the window of your building you're still going to fall and hit the ground with a sickening splat. Because there really is, after all, a thing that acts like gravity even if the word is just a placeholding label. And there really is a thing that acts like "mass" waiting at the bottom to splatter you, even if you can't define it other than circularly.
It would be awkward to have to take your book and bang your head with it like the Monty Python penitent monks every time you wanted to use the concept of "mass" in chemistry or physics. The sensation of the weight and impact with your head, and the solidity...these are what "mass" really is. But gestures and nerve impulses don't work very well for communication across time and space. So we distill these manifold realities down into little words which are imperfect and fuzzy.
"Mass" is a placeholder for the weight and impact and size of that book banging your head (and "book" is the placeholder for the thing full of paper or paper and polyester and ink, et al, that you're swinging). "Mass" and "book" are both imperfect, fuzzy-edged concepts. But NOT, as the Analytical School would have you believe, SO completely intangible that they (or your head you're hitting with the book) don't exist except in someone's mind.
Language is somewhat indeterminate, but that doesn't mean that it is RADICALLY indeterminate. Thoughts are expressed in words, and it's all fuzzy edged. That doesn't mean that they don't exist at all.
What it means is that the universe is analog, not digital.
The Analytical School would prefer to deny that there is any universe at all if it can't be perfectly digital.
Einstein had a similar sort of temper tantrum about uncertainty, saying "God does not play at dice with the universe." But actually, yes God does, and if we know everything that can be known about things, we STILL can't perfectly predict outcomes, because the universe itself is not digital. It has rules, and slop. Some folks say that slop doesn't exist and it's just our ignorance. That is pure faith, and wrong.
Others, like the Analytical School, essentially say (if you boil it all down) that BECAUSE OF slop, there are no rules and it's all our arbitrary assigning of rules and parameters. They're wrong too. Yes, there is arbitrariness and circularity in definitions. But you'll still get a headache from smacking that lump into your head, whether you call it "mass", "a book" or even a "head" or not.
If there is no objectivity, then why does everybody die?