Economics may feel we are promoting selfish ends – firms maximise profits, consumers maximise their personal utility. Adam Smith claimed pursuing selfish goals ended up in improving the greater good. But, in economics we also try to consider the impact of our actions on other people. If a firm produces chemicals, it may make a profit, but cause an external cost of pollution. To ignore this external cost would be to create an inefficient outcome. We should make the firm pay the cost of its pollution so that it has the incentive to minimise or halt external costs. Externalities are everywhere. Even your decision to study economics could have positive externalities in the future. For example, you could end up being an economics teacher helping others learn all about economics.