Abstract
In this paper we view the first order set theory ZFC under the canonical frst order semantics and the second order set theory ZFC_2 under the Henkin semantics.
Main results are: (i) Let M_st^ZFC be a standard model of ZFC, then
¬Con(ZFC + ∃M_st^ZFC ).
(ii) Let M_stZFC_2 be a standard model of ZFC2 with Henkin semantics, then
¬Con(ZFC_2 +∃M_stZFC_2).
(iii) Let k be inaccessible cardinal then ¬Con(ZFC + ∃κ).
In order to obtain the statements (i) and (ii) examples of the inconsistent countable set in a set theory ZFC + ∃M_stZFC and in a set theory ZFC2 + ∃M_st^ZFC_2 were derived.
It is widely believed that ZFC + ∃M_stZFC and ZFC_2 + ∃M_st^ZFC_2
are consistent, i.e. ZFC and ZFC_2 have a standard models. Unfortunately this belief is wrong. Book. Advances in Mathematics and Computer Science Vol. 1 Chapter 3
There is No Standard Model of ZFC and ZFC2 ISBN-13 (15) 978-81-934224-1-0
See Part II of this paper DOI: 10.4236/apm.2019.99034