jcsd
Science Advisor
Gold Member
- 2,112
- 13
I think Neutron Star one of your main misconceptions is the between naive set theory and ZF set theory. naive set theory which is the set theory of Cantor's day the empty set is not axiomatic as you are allowed to define sets by shared properties of their mebers and clealy if you define the shared properties of the members of a set in such a way that it cannot have any members you get the empty set (for example {x|x is a nonegative real number less than zero} defines the empty set). However defining sets in such a way leads to paradoxes such as Russell's paradox.
ZF set theory remedies this by saying that a set is only defined by it's members, in ZF set theory the empty set is axiomatic and as far as I am aware no paradoxes arise because of it's inclusion.
Secindly this i sgetting off track as Peano's constructio of the nautarl numbers are not depedent on whethr or not the empty set exists (it is not an orginal idea to notice that sets are defined by ther members yet the empty set has no members, it has been pointed out before, but no logical inconsistenty arises because of this state of affairs).
ZF set theory remedies this by saying that a set is only defined by it's members, in ZF set theory the empty set is axiomatic and as far as I am aware no paradoxes arise because of it's inclusion.
Secindly this i sgetting off track as Peano's constructio of the nautarl numbers are not depedent on whethr or not the empty set exists (it is not an orginal idea to notice that sets are defined by ther members yet the empty set has no members, it has been pointed out before, but no logical inconsistenty arises because of this state of affairs).
