The argument from analogy is based on a comparison between the universe and a machine: The universe, it holds, like a machine, exhibits ordered complexity; the universe, it concludes, like a machine, has a designer.

A machine, however, is not the only thing to which the universe might be compared. In his Dialogues Concerning Natural Religion, David Hume’s character Philo offers two alternative analogies for the world, each of which yields a rather different view of its origins.

The Universe is like an Animal

Philo’s first alternative analogy compares the universe to an animal:

“Now if we survey the universe, so far as it falls under our knowledge, it bears a great resemblance to an animal or organized body, and seems actuated with a like principle of life and motion. A continual circulation of matter in it produces no disorder: a continual waste in every part is incessantly repaired: the closest sympathy is perceived throughout the entire system: and each part or member, in performing its proper offices, operates both to its own preservation and to that of the whole. The world, therefore, I infer, is an animal.” [David Hume, Dialogues Concerning Natural Religion, Part VI]

If we accept that there is indeed a similarity between the universe and an animal, the principles of analogy would presumably support the inference that the universe is the offspring of two other universes.

The Universe is like a Vegetable

Perhaps a little more plausible is Philo’s second analogy, which likens the universe to a vegetable. This suggestion is raised by Cleanthes in objecting to the animal analogy:

“… it seems to me, that, though the world does, in many circumstances, resemble an animal body, yet is the analogy also defective in many circumstances, the most material: No organs of sense; no seat of thought or reason; no one precise origin of motion and action. In short, it seems to bear a stronger resemblance to a vegetable than to an animal.” [David Hume, Dialogues Concerning Natural Religion, Part VI]

When Philo is challenged by Demea to explain how the world might arise from vegetation, Philo confidently replies,

“Very easily… In like manner as a tree sheds its seed into the neighbouring fields, and produces other tress; so the great vegetable, the world, or this planetary system, produces within itself certain seeds, which, being scattered into the surrounding chaos, vegetate into new worlds.” [David Hume, Dialogues Concerning Natural Religion, Part VII]

There are even echoes of Philo’s suggestion in some modern cosmologists’ suggestions that universes are formed in black holes.

Whatever alternative analogy for the universe to that of a machine is used, the point is the same:

“The world plainly resembles more an animal or a vegetable than it does a watch or a knitting-loom. Its cause, therefore, it is more probable, resembles the cause of the former. The cause of the former is generation or vegetation. The cause, therefore, of the world, we may infer to be some thing similar or analogous to generation or vegetation.” [David Hume, Dialogues Concerning Natural Religion, Part VII]