The teleological argument was not articulated and popularized as an argument for the existence of intelligent causation (God) until William Paley (1743-1805) authored his seminal work Natural Theology. Arguments for designed existence long before Paley. Plato (429-347 BC), in Book X of The Republic, presented an argument for design. In the Philebus dialogue, Socrates is discussing nature with Protarchus and Socrates appeals to the apparent order in nature. Plato articulates that “mind rules the universe” and that the mind is the cause of all. The famous Roman orator, Cicero made a similar argument in On the Nature of the Gods (45 BC), that man may infer design by intelligent causation, that of a mind.
Paley resumes and revitalizes the argument by applying analogy to it. He states, “When one encounters a watch, the complexity of this artifact and the interrelations of its parts lead to the inference that it was the product of a purposive design.” The complexity of life exhibits the design like that of a mind. The Scottish Enlightenment philosopher, David Hume (1711-1776), responded to Paley’s claims and objected to the argument from analogy on nine different points in his work Dialogues Concerning Natural Religion.
Hume’s first objection was that the argument does not conclude that God exists, merely a designer. Using Paley’s work as the referent for his objections, this may seem appropriate since Paley spends the large majority of his book reviewing the attributes of the designer, whom he calls God. The problem with this objection is that Paley arrives to the attributes and identifies the designer only after other metaphysical implications and other evidences. Hume’s objection is precisely the argument. The argument does not argue for God, it argues for a designer.
The second objection is that one may only use analogy to argue for things that are similar, but the universe is unique. The error here is that everything is unique in its own respect. In order to properly use analogy, there must be at least some properties of the two things being compared for it to function. The third objection Hume proposed was that analogy can only be used for things that have been experienced, and no one has experienced the beginning of the universe. The response would be that it is not true, scientists infer the existence of operations of inexperienced entities all the time and analogizing the cause and effect relationships from what is already known by experience. Fourth, the designer would need a designer and so on to an infinite regress (presupposing the impossibility of an actual infinite). This objection would bring an abrupt halt to all scientific inquiry. One does not need an explanation of the explanation in order for that explanation to be the best explanation. This is particularly true if the explanation is an agent; agent causation is internally originating without any necessary external causes to consider.
Hume’s fifth objection was that all known designers are corporeal human beings, therefore the most one can infer is a super human being. This objection is similar to the first objection, not all properties have to be similar in using an analogy. Sixth, why would the design proponent not postulate more than one designer since there is no evidence of a single designer? This would be a simple application of Occam’s razor, the principle of simplicity argues for only one unless there is evidence for more. Even if the design proponent was to concede this objection that would be entirely within the scope of the argument’s claims because it does not defeat the need for at least one. Seventh, the universe may be more like an organism than a machine. This objection is a repetition of one of the arguing points for the design proponent because he claims that organisms still show evidence of design.
Hume’s eighth objection is that it is still possible that order in the universe was brought about by chance and randomness. This is a misunderstanding of the argument. Referring back to the evidences for design, the chance probability is infinitesimally small. The design argument merely argues for the best explanation and the greatest probability. The final objection Hume raised to Paley’s argument was that there are many signs of disorder in the universe. Hume has an implicit concession of design within his own objection. One can only infer disorder if there is supposed to be order. The whole universe must not even exhibit order to use the argument, all one would need is one piece of evidence that exhibited design to make the argument.