I support Jeremy Corbyn and the Labour Party in saying we are better in than out of Europe. These are my reasons based on the arguments I have heard:
1. To be a single market the EU provides and requires a) industrial production standards, b) labour protection standards and c) environment protection standards that the UK. These require structures that the UK will have to subscribe to if it wants to trade preferentially as part of the single market. Withdrawing means either losing preferential access to the single market or having access while not having a say in making the rules.
2. The departure of the UK may well destabilise an EU already under stress. Varoufakis argues that there is likely to be a split between the ‘Germanic’ countries and the rest with negative social and economic consequences that would affect us in the UK.
3. Without a strong Europe the framework of protections already mentioned is further endangered and trade agreements such as TTIP will be even more weighted towards the global corporatocracy and more difficult to oppose.
4. Outside of Europe the UK is likely to be pulled even more towards the US economically and militarily.
5. Racism/fascism in European states is more likely to be moderated by a strong Europe including the UK than by a fragmenting Europe.
6. Many social and economic programmes run by local authorities and charities in the UK depend on European funding; these are likely to be lost if we leave the EU.
7. If England votes for Leave and Scotland votes heavily for Remain further strains will be put on the Union and there will be renewed calls for Scottish independence.
8. A Leave vote will be seen as a victory for the Right of the Conservative Party even if it is a defeat for Cameron. Jeremy Corbyn and the Labour party will be immediately weakened whereas Jeremy could build on a Remain vote as his strategy is likely to be seen as having been effective.
I am sure there are many other reasons that I do not know but these are strong enough for me.