It seems to be the general opinion that absolute certainty is not something that we humans can hope for; that the best we can attain is a highly established near irrefutability. A doubt will always remain.
I would like to start by discussing two different types of certainty. First is the general kind of certainty which can be characterized by what might be described by ‘facts.’ Facts are things that anyone can study and appreciate to be highly established, e.g. the theory of gravity: things fall to earth.
The next kind of certainty is more personal. One may be certain that a specific person is the most amazing person on the planet, but this certainty resides only within that person. This is not to say other people could not become as certain, but that the certainty is more specific to those people in that specific relationship.
I believe that both general and personal certainties of the highest nature are still subject to doubt. Gravity may suddenly take a vacation and the love of your life may disappoint.
How we react to each of these situations is important. If certainties of the general nature suddenly changed then we would investigate why and incorporate this new fact into our understanding. If something we thought was certain in the personal sense did not act the way we thought it (or he or she) would then we have to reevaluate how we are going to approach our life looking towards the future.
Upon discovery that what we thought was certain was not so certain we then adapt to this new information. But what happens if we are unable to do so? Imagine gravity reversed acting the way it normally does on a worldwide scale. Life as we know it would cease. We would all be dead within an instant or two and hence we would be unable to adapt to this new situation.
However, this situation prevents us from adapting to it because we are currently unprepared to deal with it. Someone is a space capsule might be able to carry on. Likewise someone who has suffered a great personal tragedy may be emotionally damaged but, with the support of family and friends, can persevere.
Considering such physical and emotional damage is not pleasant. It is, however, instructive in considering a further sort of damage that may result from uncertainty. A person may receive such a shock from something that they thought was certain that they are not able to adapt at all- such a shock that the reasoning of the person is permanently affected.
Now if that person were asked before hand about such a situation, he or she could respond that it is beyond anything they have ever considered. This would not be due to a lack of creativity in imagining possible situations, but that to imagine such a thing would to be to doubt the very foundations that permit rational thought. Hence, in this instance, the person could claim absolute certainty: a claim tied to ones sanity is absolute because it does not permit doubt.
You may claim to have absolute certainty if you are willing to wager your sanity on it. Please be careful.