Why is this?
Let's say there's an interbreeding population of birds. Half a million years from now, the birds aren't able to breed with their ancestors and produce fertile offspring any more.
So why can't one say that this interbreeding population is a species at every time during the half million years?
They wouldn't be considered the **same** species at the beginning and at the end of this period, but they'd be an identifiable species at each instant.
Or is the alleged problem the fact that species are a fuzzy concept, as Darwin pointed out here. You've been on enough crevo threads to be familiar with ring species. (A and B produce fertile offspring, so do B and C, but A and C don't)
Or am I missing the point entirely? (I'm not sure what "universal species" is supposed to mean; what part of the link you provided applies here?)
The important thing is that there is supposedly a conflict between philosophy and reality. Obviously, therefore, reality is in error.
A universal is an abstract term that applies to a class of things. The term applies to the nature of all members of a class, rather than an individual member, i.e., this chair versus "chair," the universal term. In the act of apprehension, the mind abstracts the nature of the subject, that is, what exists in every member of the species. Upon reflection the mind may attach a term to this abstraction, the universal term, "chair," in the example. The terminology, "genus" and "species," derives from this Aristotelian concept and was carried over into the field of biology.
The question arises, what is the relation between the universal idea and the concrete individual? Is the relationship certain? If not, human communication becomes fundamentally uncertain, since we communicate by way of universal terms. See the section, "In Modern and Contemporary Philosophy," in the link that I provided. The solution is given under the subhead "Moderate Realism."
Let's say there's an interbreeding population of birds. Half a million years from now, the birds aren't able to breed with their ancestors and produce fertile offspring any more.
So why can't one say that this interbreeding population is a species at every time during the half million years?
But is the ability to interbreed what constitutes a species of animal, in the broader philosophical sense? Consider that a child apprehends the nature of "squirrel" upon seeing a squirrel for the first time, without knowing anything about the interbreeding of species or even whether other squirrels exist.
If after 10,000 years, the "squirrel" was to develop stubby wings, while still maintaining the ability to interbreed, would the "squirrel" still be a squirrel? It seems not, because were it possible for the same child to travel to the future, he would not apprehend the same species.
Conversely, consider the case of a hydrocephalic infant. We apprehend the child to be a member of the species "human," yet the hydrocephalic infant lacks what seems to be essential to human nature, a brain. It's foolish for people to argue that the child is not human, because such people will refer to the hydrocephalic child as "a child born without a brain." The child's humanity is assumed and reflexively apprehended.
So in the first case we apprehend a member of a species that has undergone a "minor" evolutionary change as a member of a distinct species separate from the original species, and in the second case, we apprehend the species of an individual that differs dramatically from other members of its species as a member of the same species.
The mind then apprehends species in a manner at times antagonistic to biological methods of categorization.
They wouldn't be considered the **same** species at the beginning and at the end of this period, but they'd be an identifiable species at each instant.
The difference between species at each instant would have to be almost immeasurable. Yet it would be necessary for the mind to apprehend each stage in development as a distinct species, since the mind apprehends diverse species regardless of biological means of classification. Yet the problem of the categorization of the hydrocephalic child arises even more acutely. How is it possible for the mind to recognize a hydrocephalic child as a member of the species human, yet differentiate between extremely fine gradations of (hypothetical) missing links?