Full Idea
To understand what is said in an utterance of 'The first dog born at sea was a basset hound', one needs to know what the world would have been like in order for what was said in that utterance to be true.
Gist of Idea
To understand an utterance, you must understand what the world would be like if it is true
Source
Robert C. Stalnaker (Reference and Necessity [1997], 3)
Book Reference
Stalnaker,Robert C.: 'Ways a World Might Be' [OUP 2003], p.172
A Reaction
Put like that, the idea is undeniable. Understanding involves truth conditions. Does mean involve the understanding of the meaning. What do you understand when you understand a sentence? Just facts about dogs? Or something in the sentence?