NS,
Evidence for gravity is not evidence against pixies causing it. One is a description of the phenomenon, the other is an explanation for it, so you're making a category error there.
You’re better than that, but ok:
Proposal 1: gravitational effects are caused by the warping of spacetime and the motion of objects through the warped spacetime.
Proposal 2: gravitational effects are caused by invisible pixies holding stuff down with very thin strings.
On the basis of the reasoning and evidence available to you, would you determine that one proposal is true and the other is not true, and would you also call your determinations “knowledge”?
As to non purposive vs purpose, all you have is no evidence for purposive, and then defining that as evidence for non purposive, it isn't.
Yes, I have evidence for non-purposive and no evidence for purposive. I also have arguments for purposive that I can falsify, and arguments for non-purposive that I cannot falsify. Which is the same situation I have for gravity vs pixies.
What’s the problem with calling the deductions that follow in either case “knowledge”?