Full Idea
'Recursion theory' is the subject of what can and cannot be solved by computing machines
Gist of Idea
'Recursion theory' concerns what can be solved by computing machines
Source
Feferman / Feferman (Alfred Tarski: life and logic [2004], Ch.9)
Book Reference
Feferman,S/Feferman,A.B.: 'Alfred Tarski: life and logic' [CUP 2008], p.228
A Reaction
This because 'recursion' will grind out a result step-by-step, as long as the steps will 'halt' eventually.