AT meetings up and down the country looking at a Scottish Constitution, a common question is: “Should we consider having two chambers in the parliament of an independent Scotland?”

The 19th-century political philosopher John Stuart Mill argued in Considerations On Representative Government that the question of whether or not to have a second chamber “has occupied a greater amount of the attention of thinkers than many questions of 10 times its importance”.

It continues to do so. Every half-hearted plea for the reconstruction of the United Kingdom as “a federation in all but name” (whatever that means) comes complete with a

fag-packet plan for turning the House of Lords into a “Chamber of Nations and Regions”.

Likewise, the question of whether an independent Scottish Parliament should have a second chamber surfaces from time to time. In discussions about the effectiveness of the Scottish Parliament, or the quality of legislation, the lack of a second chamber at Holyrood is highlighted as a shortcoming that ought to be remedied.

Would we be better governed – with greater wisdom, moderation and inclusion – if we had another chamber, into which hot legislative issues could be poured to cool? Would a few independent-minded senators, alongside party-political MSPs, help to better hold the government to account, and ensure a range of views are represented? Or would a second chamber be an unnecessary complication and expense, with few benefits that could not be achieved in other ways?

It is worth noting that a second chamber is not a necessary feature of a functioning democratic system. What’s important is not the number of chambers, but that certain functions are performed: review, scrutiny, bringing expertise to bear, representing diversity and protecting the constitutional order against majoritarian abuses of power.

In Europe, many of the countries to which Scotland wishes to be compared have only one chamber: Denmark, Finland, Luxembourg, Norway and Sweden are on this list. All of these are some of the best governed, most progressive, deeply democratic states.

The functions of a second chamber are, however, performed in other ways. For a start, they all have constitutions that can be amended only by special procedures, giving the opposition, or the people, a veto over the power of a majority in the one house to alter the fundamentals at will.

They also have parliaments elected by proportional representation, ensuring the inclusion of minority opinions and (generally) ensuring no one party has overall control.

There are probably two main functions, however, that are hard to replicate in a unicameral or single-chamber system. One is the representation of geographical diversity.

There’s a legitimate concern that Scotland’s politics and public policy are too dominated by the central belt. It makes sense – that’s where most of the people are. But democracy is not just about catering to the majority; it’s also about creating systems in which all legitimate interests – including the concerns of people in rural areas – are adequately represented.

A bicameral or two-chamber system enables the primary chamber to be elected proportionately by population, and the second

chamber to be elected in a way that over-represents rural, peripheral or island communities.

The other thing that second chambers can do well is to represent the views and expertise of people from outside of electoral politics.

These people can serve partly as a “reality check” that can force a government to think again, and partly as a means of improving the technical quality of legislation.

While a unicameral system can bring in external experts to give evidence to committee, there’s no substitute for having independent and experienced people sifting through every bill. For all its faults, which are many, the current House of Lords does this, on the whole, well.

These functions can be combined. It’s possible to imagine a Scottish Senate of, say, 55 members, equipped with powers and functions akin to those of the House of Lords or the Irish Senate.

Thirty-two could be elected from local authority areas by the alternative vote system – so Na h-Eileanan Siar (pop. 27,000) would have the same representation as Glasgow (pop. 626,000). Elections could be held concurrently with local government elections – which might also boost turnout.

The remaining 23 members could be appointed, perhaps for staggered non-renewable 12-year terms, by a cross-party panel from among those who have distinguished themselves in public office or in the arts, sciences or professions, or who are otherwise representative of civil society.

This is merely an illustration, not a recommendation. Many objections could be raised against such a plan, and no doubt other ideas (including the Danish-inspired proposal in the SNP’s 2002 draft constitution enabling 40% of MSPs to suspend a bill for a year, subject to override by referendum) are also worth considering.

But there’s real scope, in a future Scottish constitution, to think creatively both about how we represent Scotland’s geographical diversity and how we more fully and permanently tap into the nation’s great expertise.