All certitude, huh? Have you checked whether the sun rose this morning? It might have been sneakily replaced by a large incandescent light source. Are you sure you're still writing in English? Are you sure that when you put your foot on the gas, the car won't brake? You didn't check that carefully before doing it? When you got out of bed, did you ascertain whether the law of gravity was still in existence?
I said "overrated" - you might want to look up the word overrated - it does not mean "faulty" or "nonexistent". "Overrated" in a qualitative comment not a quantitative comment as you are attempting to imply. But just to prove I am a nice guy I will address your issues:
First, lets define terms:
Certitude - The state of being certain; complete assurance; confidence
Have you checked whether the sun rose this morning?
The sun does not rise or fall or do back flips - the earth rotates giving the illusion of the sun rising. I would think a professor would know this. RWP: if you have certitude about the sun "rising" - you are mistaken (that is why I said certitude is overrated)
Are you sure you're still writing in English?
Which English language? Great Britain's English language? Scotland's English language (I once saw a Scottish movie that had subtitles in English and they were speaking English albeit Scottish English). Elizabethan English? Is there a pure form of the "English language" - no. There are many dialects and one person's version of English is not always understood by another person that believes they speak (or type) English. There is no one form of the English language therefore one can not have certitude one is "writing in English" (that is why I said certitude is overrated)
Are you sure that when you put your foot on the gas, the car won't brake?
Many times, in my many years of driving, my car would not start. Pressing the gas seemed to brake the car because the car would not move. I also found that pressing the gas when the car is turn off seems to brake the car also (in that it will not go). Usually pressing the gas makes the car go but not always so claiming certitude is fallacious. (that is why I said certitude is overrated)
When you got out of bed, did you ascertain whether the law of gravity was still in existence?
Yes. Gravity still works. One problem - ascertain does not equal certitude. If one has certitude one has no need to ascertain. Certitude is a state of certainty - ascertain is to DISCOVER with certainty. (that is why I said certitude is overrated)