Preface: I know that 'positive' means the acceptation in philosophy of "dealing only with facts".
[Source: 80% down the page:] Should we instead just decree that knowledge is justified true belief provided that, additionally, there is no element of luck involved? This is an odd suggestion for several reasons. First it would be odd to have a negative criterion in the definition of knowledge. There not being any luck involved[,] is not some thing[.]
[T]hat is, [the lack of luck is] an absence of a thing. Or [to wit, this lack of luck is] a nothing[.]
A nothing or non-thing cannot be a cause of something positive.
What doesn't have any being as a thing[,] cannot explain why someone knows something if knowing something is something positive.
I do not comprehend how the bold is true, even for epistemology.
For example, suppose that I lack knowledge of epistemology. Then this lack would inspire me to learn about epistemology, after which I will have gained truly positive knowledge.
So does my example attest that absence of something can generate something positive?