Absolute certainty is only found in mathematics, we all need to make use of a little confidence to walk in this world, confidence that tomorrow my car will take me to work, confidence that I will wake up tomorrow or that the bridge will not fall down as I pass by.
The world of probabilities, it is probable that this or that will happen, it is probable that tomorrow I will be sick or maybe not, that I will have to go out or not, it is probable that I will take this or another decision, but for everything it takes confidence.