This study explores decision premises that were used to manage and stabilise a complex technochange programme in a financial institution. Decision premises were extracted from business maxims, principles and rules using linguistic techniques. In the paper, the premises are juxtaposed with their consequences. The evidence of documents, observable practices and software configurations supports the analysis. It is found that decision premises form a hierarchical, self-causal as well as self-contradictory system of reasoning that was applied over any individual situation, particularly a conflict. By virtue of being several but not many, decision premises reinforce the 80-20 rule of many consequences stemming a few causes. In the case firm, decision premises were used in order to make technochange efficient as well as institute cost-saving and business ownership of software development. But there were drawbacks of intensified politics, software development delays, short-sighted capability decisions and work fragmentation for the front-line employees.