Hi @nwrickert,
There are no natural categories. There are only conventional categories and private categories.
Seriously? The category of “elements” is a purely conventional one? The distinction between the particles in the Standard Model is a conventional one? I can at least understand someone denying the existence of natural biological categories (but see the quote from Jerry Coyne below). However, when it comes to physics and chemistry, the denial of natural categories appears to fly in the face of overwhelming evidence that these categories are mind-independent.
Hi @John_Harshman,
In practice, that’s far from a sharp boundary.
You’re a phylogeneticist, so I’m going to have to accept your statement that the boundary between biological species is not a hard-and-fast one. However, evolutionary biologist Jerry Coyne, who is an expert on speciation, has this to say about the biological species concept (BSC) in a recent blog article:
The BSC is not really a definition, but, as I emphasize in my book Speciation— written with Allen Orr—an attempt to encapsulate in words the palpable lumpiness in nature that we see before us. And nature, at least in sexually-reproducing species, really is lumpy: it’s not the continuum, or “great interconnected web”, that Taylor sees. In Chapter 1 of Speciation , I give three lines of evidence for the reality of species: they aren’t just artificial constructs, or subjective human divisions of a continuum, but real entities in nature. Yes, there is some blurring in both sexual and asexual organisms, but by and large species exist as “lumps” in the pudding of Nature. If this were not so, biologists would be wasting their time studying species, and field guides would be of no use. There is no blurring, for instance, between our species, chimpanzees, and orangutans, nor between starlings, hawks, and robins on my campus. And so it goes for most of nature. Some hybrids may be formed between species, but they are often sterile or inviable, and so don’t blur the boundaries between groups.
Would you agree with this assessment?
Finally, I accept your observation that many human capacities don’t leave preservable evidence behind, but those that do include some fairly major ones (ethics, language, art, religion), and they appear to support gradualism.
Maybe it is possible that, at some point in the past, God endowed a group of hominids with the capacity to reason, or the capacity to have a relationship with God, and that this immediately produced a vast difference in their internal mental experience and made them full persons made in God’s image. Would this difference in internal mental life immediately have produced the kind of behaviour that would leave archeological evidence? I’m not entirely certain that it would… Or for another example, maybe those first image bearers began to pray to God, without engaging in ritual activities that leave any trace until later, and such archeologically-accessible ritual behaviour developed gradually even though the fundamental capacity to relate to God did not undergo any development.
Well, I’ll certainly grant that you might be right. But the notion that our ancestors were praying (and presumably believing in an after-life as well) for some 400,000 years, without even once performing a ritual burial for dead family members, is pretty mind-boggling.
For example, maybe things like language and the technological and cultural advances enabled by our capacity to reason developed gradually, even though the capacity to reason was bestowed instantaneously.
If we look around the world today, we don’t find any primitive languages, even in technologically backward societies. All languages are roughly equal, in terms of their complexity. But we have good scientific evidence that human language didn’t appear overnight: it evolved gradually. You suggest that our human capacity to reason may have been fully developed, even at a time when human language was still evolving, but it is hard to see how advanced reasoning would be possible without a well-developed language. The two seem to be inter-twined.
I guess the point I’m trying to make is that while the archaeological evidence can (with difficulty) be reconciled with Christianity, it certainly doesn’t point that way. The gradualistic pattern we find in the archaeological record, even when it comes to language, art, ethics and religion, is the very last thing that Christian theologians a few decades ago would have predicted. And the fact that they all emerge at different times is even stranger.