Institutional change for sustainable development does not happen by itself. Individuals and organizations function as actors to influence development processes. Reference is made to a "political economic person" (PEP) guided by his/her ideological orientation and "political economic organization" (PEO), guided by its "mission". Leaving present unsustainable trends is a matter of politics and ideology and even power positions, where democracy plays a crucial role. The perspectives of influential (and other) actors are essential in facilitating (or hindering) change. I will discuss ideas of the role of science in society, mainstream economics in relation to institutional economics in the spirit of K. William Kapp and Gunnar Myrdal as well as neo-liberalism as ideology (where neoclassical economics has contributed to strengthen the legitimacy of neo-liberalism). Various aspects of inertia and flexibility in institutional change processes, such as path dependence, are discussed. Emphasis is on the role of economics and how a strengthened democracy can open the door for a degree of pluralism.