Proponents of an independent Scotland draw heavily on the following arguments:
Self-determination
[...] In essence, proponents of independence argue that Scotland is a distinct nation separate from the rest of the United Kingdom, and accordingly it should control its full political authority as an independent sovereign nation-state. [...]
Nuclear Weapons
The Scottish National Party is unequivocal in its opposition to nuclear weapons, and the stationing of the UK nuclear deterrent at the Faslane naval base in Scotland, in particular. It is argued that Scottish Independence would lead to the removal of nuclear weapons from Scotland.
EU Membership
Those Scots opposed to Britain's departure from the European Union following the 2016 Brexit referendum have suggested that an independent Scotland would have the opportunity to rejoin the European Union. [...]
Opponents of an independent Scotland argue that the powers of the Scottish Parliament have now increased considerably since it was first established in 1998. Emphasising the benefits of the Union and the uncertainty around independence, the arguments typically voiced by those opposed to independence include:
Diminished international influence, for both UK and an independent Scotland
[...] Where the UK is currently a member of the G7 and the G20, and has a permanent place on the United Nations Security Council, it is argued that an independent Scotland would lose all such influence. [...]
Economic Uncertainty
At present, over 60% of Scottish exports go to England, Wales and Northern Ireland; more than the rest of the world combined.
It is argued that withdrawing from the United Kingdom might lead to a situation in which an Independent Scotland would not have the current unfettered access to its major market, and that this would result in economic uncertainty, and potential economic decline.
Issues with regaining EU Membership
Those opposed to Scottish Independence argue that it is far from likely that Scotland will be able to rejoin the European Union. It is thought that those European governments which are facing separatist challenges, such as Spain, would be unwilling to legitimise an independent Scotland and thereby incentivise their own separatist movements.