Pros: If all else fails, Britain would default to World Trade Organisation rules for trade with EU members. The global body, with 162 members, sets a limit on how high the trade barriers can be between any two nations. The WTO option means there would be no requirement that Britain bow to rules written in Brussels. Leading Brexit campaigner Nigel Farage has pointed out that WTO tariffs have fallen substantially in recent years. And as he said Tuesday night while squaring off against Cameron, "No deal is better than the rotten deal we have got at the moment."
Cons: No deal could actually be quite a bit worse than the status quo. The British Treasury has estimated that the country's economy would be 7.5 percent smaller by 2030 in the event of the WTO option, because of higher tariffs and restricted market access. And even this, the most straightforward of all options, could require marathon negotiations stretching on for years, according to the WTO's chief. Britons could also lose their rights to live, work and study in continental Europe without a deal to allow Europeans to do the same in Britain.