The question is "can you know anything for certain", well here I'm just playing devils advocate because everyone knows math is absolute. One minus one will always equal zero no matter how many times you switch the ones around. Also the reason its something we will know for certain is because numbers are basically a counting system. Once you count something and say "there is eleven apples" you cant denied or will be unsure because you counted them.
God is the absolute standard of truth and apart from Him you cannot know anything for certain. People will try and say you cannot know anything outside of your own experience and we are limited to our own perception but how would they know that since they cannot transcend their own perception? You put yourself in a box but the only way to know you were inside a box would be to look at it from the outside and without God you can't.
The question is incredibly vague and utterly devoid of any meaningful context with which to consider how best to properly ascertain any possible methods one could utilize to, with any significant, discernible modicum of confidence, gauge the meaning of the question in question, in order to provide a meaningful response.
While is this is an ancient pop philosophy question, it's also a rather incorrect and simplistic one. We can know almost anything for certain thanks to science and our own skills of observation. But it would be arrogant to believe that we can know everything. But we do know enough, and we learn more every day.
I'd say no simply cause of the existence of the 'what if' question. Like you may say the sky is blue. But I can argue what if everyone is seeing it wrong dude to some crazy reason and that it's actually purple? Or:
People call me by my name, people call me Bryan. What if you're hearing it wrong? What if people are calling you Ryan instead?
My point is, the existence of the question "what if" doesn't allow us to know anything for certain. You may think now that my real name is Bryan, but what if i was lying?
Life itself is not certain so how can one say that anything is certain. When we achieve something to our satisfaction we go through a feel good factor but have we done everything correctly to be certain that we have been successful? Rarely do we do everything correctly to be certain because it is human to err.Nothing is everlasting so nothing is certain.
As a science student, I'd argue that nothing is ever certain, especially in science. In science, we work based upon evidence and evidence is something which is used to prove any assertion. I cannot completely disprove or know for certain that an invisible flying unicorn is in my room right now. However, I haven't seen evidence of one and therefore, I choose to not believe in that until I see evidence for it, in which case I shall draw conclusions of my own.