Teleological argument: Encyclopedia II - Teleological argument - History

Teleological argument - History

Cicero made one of the earliest teleological arguments. He was writing from the cultural background of the Roman religion. In Roman mythology the creator goddess, Gaia was borrowed from Greek mythology. The Romans called her Tellus or Terra.

A version of the teleological argument was the fifth of Thomas Aquinas' five proofs for the existence of God in his Summa Theologiae:

David Hume presented arguments both for and against the teleological argument in his Dialogues Concerning Natural Religion. The character Philo, summarizing the teleological argument, uses the example of a watch. Philo is not satisfied with the teleological argument, however. He attempts a number of interesting refutations, including one that arguably foreshadows Darwin's theory. In the end, however, Philo agrees that the teleological argument is valid. (Dennett 1995, p. 29) Daniel Dennett (ibid.) claims that, although Hume was ultimately dissatisfied with the teleological argument, his cultural context prevented him from taking any of the alternatives seriously. (As it happens, during the Voyage of the Beagle Darwin was given the nickname of Philos when he took over the duties of ship's naturalist after the ship's surgeon left the ship.)

The most famous proponent of the teleological argument was theologian William Paley (1743-1805), who also framed the argument with reference to a watch in his Natural Theology.

Teleological argument - The watch argument

Although the Watchmaker analogy did not originate with Paley, he is now almost always associated with it. He presented the argument in his book Natural Theology, which was published in 1802. One theology student Charles Darwin found these arguments compelling early in his life. Darwin later developed his theory of the Origin of Species by Means of Natural Selection to put forward an alternative explanation for complexity in nature.

Many have argued against this argument, mainly by showing that highly complex systems can be produced by a series of very small randomly-generated steps. Richard Dawkins' book The Blind Watchmaker is one of the best known works following this idea.

The debate over this is closely related to irreducible complexity, the premise that certain biological structures can function only if all their substructures are present. It argues that each substructure confers no benefit on its own, and therefore cannot have been selected by an evolutionary mechanism. It then argues that the probability of all the substructures being created in a single mutation is too low to be considered possible. Counterarguments suggest that simple structures (whose probability of randomly evolving is realistic) could have themselves evolved (ie. changed) into more complex ones over time, resulting in a present structure which appears to be irreducibly complex. See Gradual Replacement.

Teleological argument - The eye argument

Many creationists cite the eye as a prime example of this principle; "What use is a partly-developed eye?" they ask. Evolutionists provide an explanation for this and may state that creationists are arguing from ignorance, for scientists have devised working hypotheses on how certain body parts and organs could have evolved.

For example, many biological cells not associated with the senses respond to the presence of light. Most notable of this group are photosynthetic cells of algae and plants. Other very primitive organisms have very rudimentary photoreceptive cells that can only tell the difference between light and dark. These organisms use this primitive sense to orient themselves correctly toward light. In other words, much less than a complete eye is actually quite useful. Yet other organisms have clusters of these photoreceptive cells that can distinguish crude shapes. Increasing the complexity, number, and arrangement of these cells will then yield rudimentary eyes that can recognize certain objects by shape and so on until an eye capable of seeing in color and three dimensions is produced (according to evolutionists, this has happened at least twice with the advent of the cephalopod eye and is currently under way with many other animal groups). Each of these states in the development of a fully functioning eye has modern analogues in the animal kingdom, and each step need only develop through nothing more than mutations and natural selection: those animals with a better ability to sense their environment with photoreceptive cells will survive to produce more young than those that don't have this ability, and so on. Evolutionists thus claim there is no need to invoke divine intervention or intelligent design.

Richard Dawkins in particular has vigorously challenged Intelligent Design arguments similar to Paley's. Furthermore, he points out that a hypothetical evolutionary path such as that given above for the eye need not even be correct; in order to refute the argument from design it need only be plausible, thus demonstrating that there are other ways in which such an organ could have come about. The title of Dawkins' book The Blind Watchmaker is a reference to Paley's example of the pocket watch. Dawkins's book River out of Eden (1995) gives an example of a computer simulation where multiple independent organisms all showed a steady progression from a light-sensitive spot to a complex eye with a lens focus.

Another counterargument to the eye example is that the human eye, if designed, appears not to be particularly well designed. To a human engineer, the light-sensitive cells in the eye are placed the wrong way around, with the nerve cells placed between the light source and the light-sensitive cells. The optic nerve therefore has to go through the retina, creating the blind spot. An analogy would be a singer that holds a microphone with the lead to his mouth and the actual pickup device pointing away from him. A putatively better design would have the cells with the nerves at the back, allowing light to hit the cells directly and eliminating the blind spot. The large percentage of people who need vision correction also suggests that the eye is not well designed.

The explanation by evolution gives major evolutionary steps of:

1. No light sensitivity at all.
2. Cells that can sense the presence of light and send a signal to the brain.
3. Development of multiple, co-ordinated cells.
4. Development of a lens to focus the light.
5. Development of the brain enabling processing of this information, into instructions to muscles which operate the organ to detect light in other places.

Creationists would counter that each step in this process is in reality, a huge leap. However, evolutionists would argue that each step is not completed in one change; rather, these are only the major milestones of development, which itself is going on all the time.

Teleological argument - The anthropic principle

A variation of the teleological argument is built upon the anthropic principle. The anthropic principle is derived from the apparent delicate balance of conditions necessary for human life. A statistical analysis of the conditions in which life could not exist, compared the fact that life does exist, is interpreted as a fine-tuned universe, designed for human life.

A counter-argument to the anthropic principle is that one could manipulate statistics to define any number of natural situations that could not possibly happen in terms of probability, but that have happened nevertheless. The key variable is that the improbable conditions were identified after the event.

Adapted from the Wikipedia article "History", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki