Full Idea
In 'Caesar is dead, and Brutus is alive' ...there are here two distinct assertions; and we might as well call a street a complex house, as these two propositions a complex proposition.
Gist of Idea
Combining two distinct assertions does not necessarily lead to a single 'complex proposition'
Source
John Stuart Mill (System of Logic [1843], 1.04.3)
Book Reference
Mill,John Stuart: 'System of Logic (9th ed, 2 vols)' [Longmans, Green etc 1875], p.90
A Reaction
Arthur Prior, in his article on 'tonk', cites this to claim that the mere account of the and-introduction rule does not guarantee the existence of any conjunctive proposition that can result from it. Mill says you are adding a third proposition.