Sometimes you need to think about it differently. I like to call it ‘thinking backwards’. Sometimes it helps to look for the inverse of the value instead of looking for the actual value.
Using @avanavana’s example of wanting blonde hair and blue eyes, I would structure my If Then column like this.
IF Hair is not Blonde
THEN false
ELSE
IF Eyes is not Blue
THEN false
ELSE
true
This way, you will get a true result only if hair is blonde AND eyes are blue. The logic will continue through each condition until it finds a match. Otherwise it falls all the way through to the last ELSE.
In your case, it would be like this:
IF Column A is empty
THEN false
ELSE
IF Column B is empty
THEN false
ELSE
true