Where do numbers come from? What is the logical basis for the existence of numbers? Are numbers defined in mathematical logic as the cardinality of set? For example, it would seem to me that 3 is defined as the cardinality of any set that has 3 elements. IIRC it was Whitehead and Russel that tried to derive numbers and arithmatic in terms of set theory and logically proved that 1+1=2. How did they define numbers to begin with? I have no training in mathematical logic, and I would appreciate a little help. Thank you.