In this Episode, I define Political Philosophy as an 'investigation into the nature, causes and effects of good and bad government.' I explain what this means and argue that we need Political Philosophy because it constructs conceptual models of fundamental notions - democracy, fairness, freedom, justice - which influence the laws, rules and regulations in society. I characterise conceptual models of networks of interconnected ideas and concepts. Examples follow in the next few episodes on power, freedom, social justice, open and closed societies.