The principle of plenitude

It’s common for unbelievers to attack Christian theism by pointing out design flaws in nature. What’s ironic about this tactic is that while unbelievers pride themselves on their respect for science, their appeal to design flaws is so unscientific.

1. The unit of optimality

What’s the fundamental unit of optimality? Is the fundamental unit an individual organism?

Suppose we ask, which is better designed: the snow leopard or the African leopard?

The question is meaningless because you can’t judge design efficiency in isolation to the specific environment in which the organism must operate. A snow leopard is better designed for a frigid, mountainous habitat whereas an African leopard is better designed for the tropics. So optimal design is correlative. The African leopard would be suboptimally designed for the natural habitat of the snow leopard.

2. The balance of nature

Apropos (1), suppose we could optimize the design of prey such that prey uniformly evaded capture by predators. Would that be a better design?

The deleterious result would be twofold: (i) predators would become extinct due to starvation; (ii) prey species would become extinct due to overpopulation, overgrazing, and subsequent starvation.

Conversely, suppose we could optimize the design of predators. Would that be a better design?

The deleterious result would be twofold: (i) prey species would become extinct due to overpredation; (ii) predators would become extinct due to exhaustion of the food supply.

To maintain the natural balance, prey must elude capture often enough to maintain a replacement rate while predators must capture prey often enough to main a replacement rate.

If you improve one without improving the other, you destroy both. So what constitutes optimal design in predator and prey species is correlative.

3. Tradeoffs

Which is better designed: a lion, leopard, or cheetah?

A cheetah is built for speed. In one respect that confers a competitive survival advantage. It can take down prey that outrun slower predators.

But its superior speed comes at a cost. It has a weaker bite than leopards and lions. It lacks the razor-sharp retractable claws. Unlike a male lion, it can’t break the neck of prey with one swipe of the paw.

What about a lion? That has advantages. Because they live in groups, a lioness or two can stay behind to baby-sit cubs while the rest of the pride is out hunting. It’s easier to corner prey when you hunt in a pack. And having more hunters raises the odds of a successful kill.

But there are corresponding disadvantages. More mouths to feed. So one must hunt more often. Also, bigger animals need to eat more, although they can also take down larger prey.

There’s a pecking order in terms of who gets first dibs of the kill. The alpha males get the “lion’s share.”

If another lion dethrones the alpha male, it will kill the cubs. So one advantage offsets another advantage.

What about the leopard? It represents an engineering compromise or mean between the powerful lion and the fleet-footed cheetah. It enjoys the upsides and downsides of a solitary predator.

Is an anteater better designed than a leopard? In one respect, the specialized design of the anteater confers a competitive survival advantage. It can corner the market on a particular food source.

But the attendant downside is that it’s totally dependent on that narrow food source. If, due to natural disaster, ants, termites, and grubs are in short supply, it will starve.

By contrast, the leopard, with its flexible design, is far more adaptable. It has many food sources. In one respect, that’s a competitive survival advantage.

But by the same token it must compete with other predators (e.g. lions, cheetahs, hyenas, cape hunting dogs) for the same prey.

Man is a limiting case of engineering tradeoffs. On the one hand, man is one of the most naturally defenseless creatures on earth. But the compensation is his superior intelligence–aided by good eyesight and the opposable thumb.

4. Intentionality

Optimality is correlative with intentionality. To assess design, you have to know what the engineer intended to achieve. For instance, there are more accurate ways to tell time than a cuckoo clock. But that doesn’t mean a cuckoo clock is poorly designed. It wasn’t made to maximize accuracy.

On the face of it, the animal kingdom seems to be designed to exhibit the sheer diversity of possible strategies, solutions, combinations, and permutations.

The principle of plenitude trumps the law of parsimony.

5. Dysteleology

Since unbelievers reject natural teleology, they forfeit the right to say anything in nature is ill-designed. Something can only be poorly designed in case it was meant to perform a certain function. But if the watchmaker is blind, then the watch wasn’t ever meant to tell time. That’s adventitious. Whether it’s fast or slow is not a design defect.