“I think,” announced Thales, “that water is the basis of all things. We observe that animals and plants need a lot of different things to live, but all of them require water; the earth is tremendously wet; rain is traditionally called ‘life-giving’; even heat comes from water, if you think about it.”

“That’s totally wrong,” Anaximenes said. “Everything in the world is really composed of air. When air condenses, it becomes water; as the condensed air cools, it becomes rock, as we see when puddles seep away into earth. When you burn wood, it becomes air in the form of smoke.”

“That’s completely ridiculous,” Heraclitus said. “Obviously, everything in the world is composed of fire. Everything changes– humans decay and die and are replaced with new humans; states change their governments; rivers erode away mountains. As the ever-changing substance, fire is what the world is made of.”

“I think it’s a mistake to assume that the universe is only made of one thing. We should adopt a more nuanced position and understand that some models apply in some circumstances and other models apply in other circumstances,” Aristotle said. “The universe is composed of four things! Water, earth, fire, and air!”

“I agree with Aristotle, but I would go further,” Karphos said. “We’re not really making truth claims when we say the world is made of things. We’re just noticing patterns– that air condenses and becomes water, that fire changes, and that animals require water. It’s a truth-claim when you say any specific thing is made of something, but it’s hard to think of a way that it could be wrong to say that things in general are made of fire.”

“Hey, guys,” Archimedes said. “What are you talking about? I invented this really cool thing with catapults, wanna see?”

“Ugh, catapults,” Thales said, “that’s so object-level. We’re philosophers. We don’t talk about how to build catapults, we go meta. We talk about the fundamental things in nature. How can you ever learn about the fundamental things of nature if you’re spending all your time talking about catapults?”

“As we were saying,” Pythagoras said. “I think the world is made of an infinite boundless thing that never ages or decays and from which everything we perceive is derived.”

“Why do you think that?” Archimedes asked.

“Well, Pythagoreanism teaches me these really useful things about triangles that are useful to me in my everyday life, so it really validates the whole system.”

“Can’t you just keep the triangles,” Archimedes said, “and not believe in the infinite boundless thing that never ages or decays?”

“No,” Pythagoras said. “The infinite boundless thing that never ages or decays helps me understand the triangles.”

“Okay,” Archimedes said, “sure, I guess. Let’s go build a catapult.”

“Sure!” Pythagoras said.

“Those catapults will be in a certain sense made out of fire!” Heraclitus said. “So be careful they don’t burn down!”