Out of the Epicureans and Stoics, who was right about the Cosmos? Both! Marcus Aurelius said he’d follow Stoic ethics whether or not the universe was random or providential (specifically deterministic). Well, it turns out they were both right.
The Epicureans believed that the universe was composed of atoms that swerve randomly/chaotically. We were just an assortment of atoms and the void. Well, they were basically right. Only atoms as we now know them are actually divisible (as opposed to what atom actually means in the Greek “indivisible). The real “atoms” of today are like quarks and leptons. On the quantum level, quarks and leptons and even atoms behave randomly. We can only probabilistically determine what their momentum or position will be. Quantum mechanics agrees very strongly with Epicureans.
What about the Stoics and their notion of the Logos? Well, Logos is just a law of the universe. It turns out that today there are many laws. Physicists hope to unify all the laws of the universe into one fundamental laws that we can derive all the lawlike equations from. The Stoics were definitely right to believe there was something lawlike to how matter proceeded through time. There are lots of patterns in nature that science has now revealed to us. There’s a rhyme and reason to almost everything today. We just need sophisticated computers to spit out equations that let us know the rhyme and reason.
What’s more? The idea of Logos as a fiery animate matter organizing inanimate matter may seem far fetched. But what if we replaced fiery animate matter with energy? Energy is the ability of matter to do work on other matter. It’s not clear exactly what the Stoics had in mind but it sounds kind of like energy when they talk about the fiery Logos. Not just the lawlike behavior of it but its input of energy.