Software (and economy) get big and complex due to emergent properties that arise from base rules. This is why, for most large projects, no one _needs_ to know t

Software (and economy) get big and complex due to emergent properties that arise from base rules. This is why, for most large projects, no one _needs_ to know the entirety and all the edge case to make modifications and improvements, you focus on base rules and build off from there. For software that would be individual components and whatever invariants you have set up. And then you you build off of these to reason at higher levels. Attempting to know the whole thing at once "and all the edge cases" is quite wasteful.