Why Does a Leopard Have Spots?
Free Floating Rationales
Rudyard Kipling dealt with this in one of his Just So stories. The idea was that once all animals had the same color and they identified each other by shape. Giraffes had one shape, antelopes had another shape, leopards and yet another and so on. After a while all the animals fled to the forest to avoid being the leopard's dinner. The light in the forest was dappled with light and shadow that broke up the shape of the animals. The animals noticed and pushed it further by changing their skin color from even tawney to a blotchiness that made them even harder to see in the dappled light of the forest. Eventually the leopard found the forest, but couldn't see the animals there because they didn't present the right shape. But he knew that the prey was there because he could smell their presence. Night came and he hunted by smell, successfully. In the morning he looked at what he had caught. It smelled like a giraffe but didn't look like a giraffe - it was all blotchy. The clever leopard realized that he could do that too - so he changed his skin so it was all spotty. And that's why a leopard has spots.
The story is full of magical beings but it is actually consistent evolution by natural selection. We know that both giraffes and leopards are engaged in a sort of arms race where each evolves to be more effective at dealing with the challenges the other presents. The Just So story presents a rationale for why leopards (and giraffes for that matter) have spots. The leopard has a rationale for having spots. ie: If I have spots it will be easier to catch prey.
Kipling presents the leopard as Leopard - rather than being an individual animal Leopard stands for all leopards.
This trick enables Leopard to be presented as an individual with cognition that can learn and decide the way that we do.
That is: the Leopard can have a rationale for what he does.
And we can see that there is certainly a good rationale for leopards having spots.
But the species Leopard does not have anything like the cognitive capacity of a leopard, let alone humans.
And yet there is a rationale for it's spots. It's just that the rationale wasn't achieved by any sort of cognitive process.
No leopard decided that leopards would have spots. No leopard could make that decision for all other leopards. So what we have is a rationale that is not associated with any sort of cognitive process of the sort that we see in individuals. It's a rationale provided by Natural Selection.
Dan Dennett calls this sort of rationale a "free floating rationale". It's a reason why something occurs that is not related to any individual's decision or idea. With a leopard we can ask questions like: What is the purpose of spots on a leopard? The spots are a regularity in leopards but that regularity is different from purely physical regularities. We know that there are reasons why the sun is a sphere. We know that it's the laws of physics that determine the sun's shape. But we don't think there is a purpose for that shape: it just is. But we do think that there is a purpose for spots on a leopard.
This brings up an important point about evolution by natural selection.
It's only in the context of evolutionary circumstances that we can talk about purpose.r
Purpose is not found among the laws of physics.
I think that people have realized that since ancient times. They could see that lots of things in nature have rationales: that is there are reasons why a leopard has spots. And they knew that physical matter alone doesn't do things for it's own reasons. And yet they could see that the natural world has many obvious rationales. Without knowing about natural selection as a source of purpose and rationales the fairly obvious conclusion was that somehow there was a level of reality apart from the physical that made decisions about reality.
But now we know better
What do you think?
I present regular philosophy discussions in a virtual reality called Second Life.
I set a topic and people come as avatars and sit around a virtual table to discuss it.
Each week I write a short essay to set the topic.
I show a selection of them here.