When rules of grammar change, meaning is always involved, whatever the formal effects of the change. This is illustrated concisely by the current expansion of the syntactic government of the past participial form of the verb base, i. e., based, in both American and British English, whereby the traditionally normative phrase “based on” is being replaced and or augmented by the variant “based around” (and even “based off of”), as heard increasingly in media language on both sides of the Atlantic.
This change is semantic as well as syntactic because it can be analyzed as an attenuation of the meaning of the complement on, which is what results when the complement changes to based around. The conceptual core of on is weakened to indicate only something circumferential (as it were) rather than solidly central. Speakers who have shifted to using based around mean something different, therefore, from those who adhere to the traditional norm.