Philo the Skeptic
Hume followed the lead of the ancient Greeks by writing is discourse in the form of a dialogue between fictional characters that represent opposing schools of philosophy. Philo is the voice of skepticism in the face of traditional theological arguments and he positions himself quite distinctly through one of the most famous similes in the entire text:
“We are like foreigners in a strange country, to whom everything must seem suspicious”
The World is Animal
Hume turns to metaphor to make several points. The text is structured in such a way that knowing how such tools of thought as reference, deduction, conjecture need to be understood to make rational connections. At one point, Hume engages a debate between random organic generation and intelligent design through the metaphor of the world being animal as his argument in favor of generation over design by having Philo enter the following into the discourse:
“The world, I say, resembles an animal, so it is an animal, so it arose from generation. The steps in that argument are jumps, I admit, but each of them involves some small appearance of analogy ·between world and animal.”
The World is a Machine
The counter to the argument supporting generation is forwarded by a fictional partner in debate. Notably, the arguments parallels the use of metaphor though proposed by separate entity:
“The world, says Cleanthes, resembles a machine, so it is a machine, so it arose from design.”
The World is Like a Ship
Hume bypasses direct metaphor in this example because he is raising a mere hypothesis; another tool of thought with which readers must be aware. In raising only the possibility that the world may be accurately compared to something that is obviously an example of design, he raises the specter of the danger that looms when making inferences to arrive at facts during debate.
“When we survey a ship, we may get an exalted idea of the ingenuity of the carpenter who built such a complicated, useful, and beautiful machine. But then we shall be surprised to find that the carpenter is a stupid tradesman who imitated others, and followed a trade which has gradually improved down the centuries, after multiplied trials, mistakes, corrections, deliberations, and controversies. Perhaps our world is like that ship.”
Which is to say that perhaps our world is the result of bungled starts, multiple corrections, wasted labor and trials and error. Or, put another way: though the world may resemble the work of a skilled designer in every way, perhaps it is actually the result of natural generative evolution.
Comets: The Seeds of the Universe
A third character also takes part in this dialogue. Demea is the stalwart defender of the dogma and orthodoxy of the Church. As such, Demea is also a skeptic of sorts: he is only skeptical of that which criticizes his dogmatism. And so it is he who poses perhaps the single most important question to Philo on the issue of his theory of the universe arising not through design, but random generation: how could it be possible at all that the entire universe could arise through the process of generation which is, essentially, comparable to procreation of the human race and propagation of plant life. Philo does not even hesitate in turning to metaphor to provide a literal explanation:
“A comet, for instance, is the seed of a world; and after it has been fully ripened by passing from sun to sun and star to star, it is at last tossed into the unformed elements which everywhere surround this universe, and immediately sprouts up into a new system.”
