Rene Descartes and Benedict Spinoza both had great intellectual justifications for their rationals. Descartes had what we would call a Bottom Up perspective of the cosmos while Spinoza had a Top Down perspective. We’ll cover Spinoza and dissect his reason another time, but one must understand the difference in these perspectives. Descartes’ Bottom Up is done by accepting nothing but what is known. What is known is “I think, therefore I exist”, which would be the bottom of our knowledge of the cosmos then working our way up through reason. The concern of Bottom Up perspective is the many assumptions one must make on the way up, making all the justifications you make on the way up fit the first knowledge one gained at the bottom. Top Down perspective is just the opposite, beginning at the furthest perception of the cosmos.
This might be difficult to conceptualize at first in the mind, but think about Google maps. First, you are looking at a street, which we would call the bottom, but you’d be able to zoom out to the city, state, country, planet, etc. Spinoza’s Top Down perspective is a complete zoom out of the entire cosmos. As I said before, this might be difficult to conceptualize but one can only imagine what this sight would look like or feel like. Spinoza gives an example for the concern of Bottom Up perspective by using a parasitic worm (I exist) in a pool of blood (cosmos) as an analogy. The worm (I exist) would see nothing around it but blood cells and particles, the worm being of tiny size would think as much as it would see, not knowing that all things inside of what it was seeing was part of a bigger picture that it was unable to fathom. Spinoza believes that if we view the cosmos from a Bottom Up perspective it would limit our understandings, like the worm that is unable to have knowledge of his true location and self.