Hi Derrick, You asked that we approach the propositions step-wise, so let me do just that. "1) One's vision is dependent on visual information travelling...which does not happen instantaneously, but takes a finite amount of time, however small..." Here is the initial assumption: finite speed of signal/stimulation. "2) Therefore, the content of one's vision in the present is always the world of the past, however recent." Here is the second assumption: that an observer is located in a distinct "here" and "now" "3) The past, however recent, cannot itself exist in the present, by definition, although a representation of it can." This follows from Assumptions 1 and 2 "4) Therefore...must instead be merely a mental simulation of it" If assumptions 1 and 2 are correct, then the conclusion of step 4 is correct, provided we look at “Simulation” as an artefact of perception, that is, a construction of some kind In order to understand where you want to go with all this, I would like you to choose between the two meanings of “artefact” from the choices given below: 1. Any object made by human beings, esp. with a view to subsequent use. 2. A spurious observation or result arising from preparatory or investigative procedures ....OR... any feature that is not naturally present but is a product of an extrinsic agent, method, or the like: such as statistical artifacts that make the inflation rate seem greater than it is. The first gives some “value “ or usefulness to perception, the other treats it as an illusion or unreality of some kind along the lines of what is called “Maya” in Hindu Philosophy