Simply, as a meta note / rational argument's sake ->

Let's assume X (Smith) makes statement S (X -> S). A few hundreds of years later, Y (Graeber) makes statement S' that refutes S and says Y -> S' and negates ~ (X -> S). Now what I'd expect is a Z, that counter-refutes Y. For example, Z -> S''. Instead, you're going back to saying yeah, we all know X -> S, so how can Y -> S' be ever true...

A starting point for ideas on rational arguments etc is https://www.lesswrong.com/library