It seems in the long standing crevo wars, we have often written a benediction to a thread that ended with the conclusion that the two sides were hopelessly divided on universals. One side of combatants often take the Aristotle position looking down and giving a hand wave to "threeness" "redness" "treeness" as you say, pointing only to a particular tree or group of trees. The other side takes the Plato position, looking up to the forms themselves.
It is particularly disturbing to me (and fortunately, fairly rare) when mathematicians take the position that universals do not exist. After all, when they name a variable in a formula, they have declared the universality of the formula itself. The radius is the same thing or form regardless of what, where, how or when a particular circle might exist or not. Thus the formula for calculating the area of a circle is portable across every domain.
The same is true with physicists whose concern is the universal theory itself which of course must be portable across every domain as well.
Often lost in the railing back and forth is the simple observation that mathematics is unreasonably effective in the natural sciences (Eugene Wigner) and vice versa (Cumrum Vafa) S dualities, mirror symmetries, the Mandelbrot set.
The prime example of this phenomenon was that Einstein was able to pull Reimannian geometry off the shelf to describe general relativity. Reiman could not have known the physical universality of the math he discovered!
If a metaphysical naturalist were reasonable in the matter (as compared to ideological or political motived) he would admit that the phenomenon squarely attests that universals exist and leaves the door wide open to theology and philosophy - in particular, Logos as betty boop has mentioned here.
IMHO, when the biologists invited the mathematicians and physicists to the table, it was a death wish.
Excellent insight/example of a (non-material) universal, Alamo-Girl! Kudos!!!
Alamo-Girl, I didn't know you were into these areas. I agree entirely with what you say.
Worth reading for the situation we find ourselves in are the later books of Alastair MacIntyre, written after his conversion from Marxism, especially his two key books, "After Virtue," and "Whose Justice? Which Rationality?" He plausibly suggests that we have three camps or communities in the contemporary western world: traditionalists, modernists, and postmodernists, and that they all talk past each other because their fundamental premises or axioms are from entirely different worlds and do not overlap.
We have certainly witnessed that phenomenon on numerous Darwin threads in the forum, where the Darwinists simply repeat the same mantras again and again, rather than respond to their opposition's arguments. I think that was because they simply couldn't SEE the arguments. Their world view (Weltanschauung) doesn't permit them to. Their answer is pure and simple: Darwin is science; if you disagree with Darwinism you are hopelessly ignorant; so we will turn to the activist courts to prevent you from passing your superstitious ignorance on to the next American generation.
Another book I'd recommend is by Thomas Nagel, who is said to be one of the three or four top living philosophers.
He is an agnostic, but he is also a truth seeker, as few philosophers are in today's academia. His book "The Last Word" is an effort to understand how, in a purely material world without God, there can be such a thing as universal knowledge. And why does the order of the universe seem to correspond to the order of our thinking? He comes very close to admitting what he cannot, as an agnostic philosopher, admit: that the only way to account for universal knowledge that can be communicated in objective language is religious. Indeed, that something like the Logos is necessary. He does not make that jump, but his book has been much discussed in religious circles by Christian philosophers, for example in a Catholic academic journal I get called, coincidentally, Logos.
Although somewhat off the immediate subject, two other books I have found extremely valuable in thinking about the nature of reality are Lynch's "Christ and Apollo," and Ralph McInerny's "Aquinas and Analogy." The latter is highly specialized but I think more important than most academic books. Incidentally, McInerny also writes detective novels.
Much of this boils down to the meaning of the word realism. In classical philosophy, the real is what lies behind the phenomena. In modernist philosopy, the real is the material. But modernist philosophy is incapable of sustaining that argument, and degenerates into scholastic specialization that has made most academic philosophy departments completely irrelevant to the real world.