When Pixar released Toy Story in 1995, they were able to capture our hearts and minds with one simple premise—What if all of our toys were sentient? Over the years, the franchise has explored themes of family, friendship, envy, love , loyalty, and did so without ever caring how or why the toys were alive. Whether intentional or not, the conceit of Toy Story 4‘s story—as well as a repeated gag throughout the film—establish new rules that seemingly govern all matter in the franchise universe.
Mild Disclaimer: While this post only references plot points that appear in many of the trailers, I do spoil a running gag throughout the film. While I don't consider any of the following to be "spoilers" in the truest sense of the word, the purest of the unsullied may want to avoid reading until they've seen Toy Story 4 themselves.
Haaave you met Forky?
In Toy Story 4, we are introduced to a new character named Forky. He's a skittish, anthropomorphized spork created by Bonnie—the child who the toys are passed to at the end of Toy Story 3—during her kindergarten orientation. As soon as he comes to life, Forky begins to cry out in a sort of psychological terror as he attempts to understand the reality he finds himself in. This isn't a simple terror of the unknown. It's not a realization that while Woody and the other toys are thoughtfully crafted, he's a makeshift abomination that doesn't deserve to live. It's nothing like this.
Forky's agony stems from his immediate recognition that his corporeal form—a disposable spork—is that of an object who's entire existence is to shovel food into the mouth of a human… once. And that once his intended purpose is fulfilled, he is meant to be cast into a trash bin to live out the rest of his life as garbage. This is not a truth that Forky learns through experience or observation. The moment he is given life, it's a fact that he knows to be true without even understanding what it means. This manifests itself as an insatiable drive to throw himself in the trash, much to the consternation of Woody. At every turn, at every free moment, Forky beelines it for the closest trash bin in attempt to quell his need to fulfill his purpose.
But what does it all mean?
While his realizations about the world are played for laughs, Forky does seemingly establish an interesting new rule about the world of the films. If you look past the humor and take a step back, you may arrive at a place where your mind finds itself blown.
I now present to you, the Forky Theorem:
Any complex grouping of matter, assembled with intent, bakes in this intent, by nature of its construction.
Put more simply, Toy Story 4 heavily implies that during the act of creation, the will and intention of the creator is baked into its creation. Furthermore, this intention manifests itself as a drive by the creation to fulfill its destiny. This rule would govern all constructed matter, whether inanimate or not.
Forky doesn't gain this knowledge when he becomes sentient. His belief that he was meant for one meal and then to be thrown away is not something he picked up by observing other sporks get used and thrown away. It's a purpose he knows to be true, deep down in his core. A purpose stemming from before he was given life.
Logical consistency throughout the series
While I refer to the Forky Theorem as "new", that isn't quite the case. This is just the first time it's being laid out for the audience. This rule of is, of course, logically consistent with the rest of the series. Throughout the Toy Story franchise, all toys have been shown to have a single desire driving all of their actions. They all exhibit a need to be played with by a kid. The whole narrative conflict of the first film involves Woody—Andy's favorite toy—reckoning with the fact that he's getting chosen to be played with less once Buzz Lightyear arrives on the scene. As the series continues, we discover that being a lost toy or a tory without a kid is to live without purpose and is the greatest tragedy outside of literal destruction.
This is not a learned or taught characteristic. Every single toy seems to be born with it. An instinctual drive that governs their every action they take. In fact, every non-human villain in the franchise becomes villainous because they are driven to cruel acts in pursuit of achieving their inborn purpose.
While some characters manage to override this drive over the course of their series arcs, most can never break free from it.