Complexity is, in a general sense, the amount of information it takes to describe something "interesting" about a system. I posit that the definition of fundamentality is equivalent to a lack of complexity. We begin our discussion with a broad question—what is "fundamental?"—and apply philosophical tools, like the linguistic principle of charity, until we whittle our inquiry down to something manageable. From then on, we meander through a series of possible solutions and rebuttals, briefly peering at applicability and elegance, until we are naturally motivated to hit upon complexity as our viable candidate. We discuss both the technical attempts at quantifying complexity and the adjustments we need to make for our case. Ultimately, we see that fundamentality is simply our attempt to understand the world's patterns, and that task is much more easily accomplished with a lack of complexity.
Michelle Xu