That’s the intellectual breach into which campaign finance reformer and activist Derek Cressman has stepped with his new book, “When Money Talks: The High Price of ‘Free’ Speech and the Selling of Democracy.” Rather than simply hold the same debate and wait for demographics to hand Democrats a victory in the end, Cressman’s book urges supporters of reform to challenge some of the basic assumptions underlying campaign finance reform’s political terrain. That includes the prevailing legal understanding of “free speech,” yes; but it also pertains to the reform camp’s vision of what is and isn’t possible, too.