 [They are] partial answers to the question under what conditions a deductive argument is explanatory […] On what I took to be the most charitable reading of them, Bolzano’s principles essentially boil down to the claim that a logically valid argument is explanatory, only if there is no argument with fewer premises, for none of the premises is there a logically equivalent proposition that is simpler, and none of the premises is more complex than the conclusion.[…] These principles, I have maintained, can be considered to be an explication of the idea that every premise and every concept in an explanatory argument is deductively relevant. More importantly, they can be considered to be an explication of the idea that explanation ought to go in hand with some kind of theoretical economy.