According to Johnson, one of the main reasons for language change is trade. He states that "commerce, however necessary, however lucrative, as it depraves the manners, corrupts the language."
Contact with other nations also contributes to language change. He also mentions the influence of many internal factors. He states that a society that has different classes will probably have more language change because those with more leisure time will have time to think and so will expand language with the incorporation of new ideas.
Johnson also points out language misuse by illiterates and excessive use of colloquialism as reasons for language change. Johnson believes that "illiterate writers will, at one time or other, by public infatuation, rise into renown, who, not knowing the original import of words, will use them with colloquial licentiousness, confound distinction, and forget propriety."
