Duckworth argues that Austen's heroines aim "to support and maintain an inherited structure of values and behavior", often with an explicit Christian stoicism. In his interpretation, Austen's heroines' morality is based in religious principle and duty to society. Austen's novels portray "society" positively, and her novels end with hero and heroine united in the company of true friends, society "reaffirmed around the central union, and the social fragmentation that initially threatened ... reconstituted through individual commitment into a new whole." Scholars such as Claudia Johnson argue that Austen is indebted to the political novels of the 1790s and that she is sceptical of the paternalistic ruling order. For example, Johnson argues that "Sense and Sensibility" is a critique of primogeniture and the arbitrariness of property inheritance. She contends that the novel is not, as it is often assumed to be, "a dramatized conduct book patly favoring female prudence over female impetuosity". Johnson concludes that Austen created "a progressive middle ground" after the blistering political fights of the 1790s. Kelly agrees, writing that Austen embraced the "hierarchical social structure and constitution of church and state" yet also recognized that they needed reform. Jenkyns supports this view: "What must be said emphatically is that she does not praise the existing state of society." He gives as examples such flawed representatives of the status quo as Sir Walter Elliot, Sir Thomas Bertram and Emma Woodhouse's father; Austen's admiration of the Navy as an avenue of social mobility (the Crofts and Captain Wentworth in "Persuasion"); and her sympathetic portrayal of characters who are "in trade" or newly risen from it (Bingley and the Gardiners in "Pride and Prejudice", the Westons and Frank Churchill in "Emma"). One of the most hotly debated topics in Austen criticism is the role of colonialism in Austen's works. In 1993 Edward Said published "Culture and Imperialism", in which he argued that the relationship between the English and the Antigua estates in "Mansfield Park" represents the relationship between the center and the periphery of the British empire. He argued that "England was surveyed, evaluated, made known, whereas 'abroad' was only referred to or shown briefly without the kind of presence or immediacy lavished on London, the countryside, or northern industrial centers such as Manchester or Birmingham." Specifically, "Thomas Bertram's slave plantation in Antigua is mysteriously necessary to the poise and the beauty of Mansfield Park, a place described in moral and aesthetic terms" but it is rarely mentioned.