Say a person is considering whether to drink alcohol or not. One will weigh up what they have to gain or lose from this. If one values the drink more than it costs them, it will be purchased, as the private benefits outweigh the private costs. However, if consumed in excess, that person might inflict unwanted costs on society, such as needing healthcare assistance. Here, the social costs (MSC) outweigh the social benefits (MSB), yet because to the drinker the private benefits were greater than the private costs (MPC), the drink was consumed regardless. Here, there is ‘spillover’ from the market, and overproduction means that the result is inefficient i.e. there is wellbeing left unaccounted for. Hence, one way to solve this is to increase the private costs, for example, through implementation of a