Today is not April Fool’s Day.  I can prove this in several ways:

Proof #1:  Was yesterday April Fools’ Day?  No.  Was the day before yesterday April Fools’ Day?  No.  Hence, by induction, we may conclude that today is not April Fools’ Day.

Proof #2: April Fools’ Day only happens once a year.  So, the probability that today is April Fools’ day is 1/365.  That’s almost 0.

Proof #3: If today were April Fools’ day, there would be unanimous consensus about the fact, but there isn’t, because I disagree.