What is Certain Knowledge ?

It has 3 meanings. 'Certain' can mean 'particular', as in 'that certain someone'. You can knowledge of particulars; hot stoves, fast cars, the taste of ice cream, etc.

"Certain” represents an assessment of the evidence for a conclusion; it is usually contrasted with two other broad types of assessment: “possible” and “probable.” . . ."

It also means the belief that one's knowledge is correct. But that does not guarantee it is accurate.

"Infallibility is not a precondition of knowing what one does know, of firmness in one’s convictions, and of loyalty to one’s values." http://aynrandlexicon.com/lexicon/certainty.html

This possibility of 'infallibility' also plays into "Errors of Knowledge vs. Breaches of Morality" http://aynrandlexicon.com/lexicon/errors_of_knowle...

I think the question is misguided.

The most certain objects of knowledge, mathematical entities like number, are necessary fictions. It is their falsity that makes them useful and powerful. The number 2, for example, represents two identical objects (impossible) and the addition of standard identical units (false). Nietzsche would say, as would Plato and Kant, though Hegel seemed to think they were "more true" than "real" objects, that these necessary illusions are what make life bearable.

In fact, Nietzsche did say just that in Beyond Good and Evil.

"Certain" knowledge... is confusing, mostly because I can't think of a genetic definition of certain or knowledge. A genetic definition is one that describes how something is generated, like an ellipse is the shape formed by attaching a piece of string to a pencil tied to two nails.

the question implies 1 it is complete 2 it is free from doubts eg 2plus one is three. other than in numbers in every thing else no knowledge is ever complete including the knowledge about you it is subjective. but you 'exist' is complete free from doubt an experience = your knowledge when supported by experience you are eternal existence= this knowledge is certain

Self realization or soul realization . once you came to know who you are you reach the highest state of knowledge only that is certain for all time ..

we are all clever we in basic terms ought to the best thank you to apply our information and talents. you're probable large at specific issues that i could be a dumb-head at. Ex: in school Mr or Mrs regardless of PHD declare they are clever yet are finished morons to the least complicated issues, issues we are smarter than them in without a PHD. whats up yet Like God be conscious says "If we lack expertise ask for some"