02/07/2015 06:21 BST | Updated 01/07/2016 06:59 BST

Britain and the EU: What Would Machiavelli Do?

Machiavelli is famous for his manual of power, The Prince, but it now seems likely he wrote it in an attempt to curry favour with the de Medici family who had usurped Florence's republican government. He wanted back his old job as a top bureaucrat in the city-state, but when the ploy did not work, sat down to write his Discourses on Livy. The Discourses express his real view that republics, not monarchies or oligarchies, are the best form of state, and the ticket to freedom and prosperity.

While republics had the appearance of messiness and unpredictability, Machiavelli noted, in fact popular enfranchisement and power provided a stability that tyrannies and oligarchies lack. He went further by suggesting that only states which are meritocratic, allow immigration, and have a wish to grow large will be able to command lasting influence in the world.

Life imitating nature, Machiavelli observes that "it is neither natural nor possible that a puny stem should carry a great branch, so a small republic cannot assume control over cities or countries stronger than herself". Any state, he said, faces a choice of having a larger population that makes it possible to extend its dominion (at the cost of some unruliness), or having a more tightly ordered state of affairs which, while lessening internal disorder, also makes for weakness in military reach.

Sparta was able to get dominion of all of Greece, but could not sustain it, and neither could Venice keep up its control over Italy. Neither Sparta nor Greece was set up to command and keep and empire like Rome which, when it conquered surrounding cities and civilisations, allowed the inhabitants to become Romans, thus swelling its population (it even allowed some slaves to escape their shackles). Rome vacuumed up the best and brightest, and made sure they were rewarded.

Machiavelli's emphasis on openness, freedom and size as the source of national power and wealth is a recipe which holds true today. Would Britain really be better off as a modern-day Sparta or Venice, self-contained, in total charge of its borders, and perpetually on the defensive? Or is open, expansive Rome the better model, which after all lasted much longer than anyone expected? Britain will never return to its former imperial might, but it can be a significant player in the big 'empire' of our time, the EU, which is committed to the same meritocratic values most Britons hold, and not least the equality of member states.

The American Founding Fathers also looked to Rome. In theFederalist Papers, Alexander Hamilton and James Madison argued for central government that was strong enough to bind together America's 13 colonies and states, and to be able to raise taxes to fend off foreign attack. Many people felt the Constitution was an attempt to create a new secular monarchy, with president in place of an English king, but Madison argued that the weak federation that then existed was not enough to create a sense of national unity or purpose. Ease of interstate trade, uniformity of measures, freedom of movement and equality between states (big or small) would also be necessary to this project. Everyone would benefit if government - with suitable checks and balances on its power of course - was big enough to get things done.

Madison made a famous case for the sheer size of the American republic, countering a popular view that it would be too big and unmanageable. He argues that size ensures there will be a good number of groups serving different interests, making it less likely that one can dominate or tyrannise the rest. In a single state or confederacy, a religious sect or a particular political position, such as the forced redistribution of property, has a much greater chance of success, but across a vast nation such singular interests are never going to hold sway. What you get instead is government that tends to reflect and promote the interests of the whole.

Hamilton's and Madison's vision of a sprawling, pluralistic republic guided by a few fundamental principles, with its machinery of government built on checks and balances, turned out to be exactly what the new nation needed to flourish. Madison's great insight was that you would never get stability by letting nations split up into smaller regions according to religion or ethnicity or some other commonality. Rather, America would be at its best and most powerful seen as a great umbrella under which many peoples and their values could thrive protected. Their competing interests would naturally be a check on each other. In pluralism was strength.

The leaders of today's nationalist breakaway movements might profit from reading The Federalist Papers and Machiavelli's Discourses. They may be reminded of the many benefits of strong unions with large, heterogeneous populations, and the costs of going it alone. With the clock now ticking on an in/out EU referendum, this warning comes to us from the past. Do we want to be like Rome (big, powerful and open) or like Sparta (small, paranoid and closed)? Along with the founders of the most powerful nation, perhaps we should listen to the patron saint of power himself, Machiavelli.

Tom Butler-Bowdon is the author of 50 Politics Classics - Freedom, Equality, Power (Nicholas Brealey).