Full Idea
'Introduction rules' state the conditions under which one may deduce a conclusion whose dominant logical operator is the connective. 'Elimination rules' state what may be deduced from some premises, where the major premise is dominated by the connective.
Gist of Idea
Introduction rules give deduction conditions, and Elimination says what can be deduced
Source
Ian Rumfitt (The Boundary Stones of Thought [2015], 1.1)
Book Reference
Rumfitt,Ian: 'The Boundary Stones of Thought' [OUP 2015], p.4
A Reaction
So Introduction gives conditions for deduction, and Elimination says what can actually be deduced. If my magic wand can turn you into a frog (introduction), and so I turn you into a frog, how does that 'eliminate' the wand?