 Very little progress was made on CH and GCH. In fact, in the early era of set theory the only other piece of progress beyond Cantor's result that 2κ &gt; κ (and the trivial result that if κ ≤ λ then 2κ ≤ 2λ) was König's result that cf(2κ) &gt; κ. The explanation for the lack of progress was provided by the independence results in set theory: 