The election of Donald Trump last November had an unexpected result in my household. My 16-year-old son developed a fascination with systems of governance. The disparity between the popular vote – won by Hillary Clinton – and the electoral college that propelled Trump into office offended his sense of justice.

It’s been a recurring topic of conversation ever since. We discussed monarchy versus republicanism over pizza. It took several breakfasts to cover communism satisfactorily. I hadn’t even had my second cup of coffee the morning we moved on to Julius Nyerere’s dream of pan-African socialism.

Discussing these assorted electoral arrangements with a neophyte forced me to re-examine tenets I’ve tended to take for granted. Sure, I’ve grumbled about disproportional representation, raged over democratic deficits and moaned when the verdict of the people didn’t coincide with mine. But it took those conversations with a 16-year-old to remind me of the idealist I used to be, and to consider what true reformation might mean.

Everybody complains about the system, winners and losers alike, not least because it militates against a diverse range of views within the Westminster parliament. It’s subject to Duverger’s law, a principle outlined by a French sociologist. First-past-the-post in single-member constituencies tends to produce a two-party system. Smaller parties that threaten to break through fall away over time because to opt for them is seen as a wasted vote.

And even when other parties manage to win a handful of seats, their presence makes no difference to how we are governed. We still end up with one of the two main parties running the show. There may be more than two parties in the House of Commons but there are only two parties of government.

We saw that in the last parliament only too clearly. The SNP won all but three seats in Scotland, which meant in effect that the people of Scotland were entirely disenfranchised in the Westminster parliament. The governing party and the opposition had power but no mandate and the MPs we did vote for had no power to exercise their mandate. North of the border, we were at the mercy of a party that owed us nothing.

Facebook Twitter Pinterest SNP supporters celebrate in Glasgow in the 2015 election. Photograph: Jeff J Mitchell/Getty Images

But it’s not just the Scots who feel disenfranchised. The nature of first-past-the-post means millions of voters feel shut out of the democratic process. If the 2015 parliament had been constituted on the basis of votes cast nationally, as opposed to by constituency, there would have been 240 Tories, 198 Labour, 82 Ukip, 51 Lib Dems, 31 SNP and 25 Greens, plus 17 others. That’s a lot of people who voted for something they didn’t get. If ever there was a case for reform, that has to be it.

And the beauty of it is that in the UK we already have a voting system that produces a much more proportionate representation. It’s been in place since 1999 and has governed the results in five elections so far. In Scotland, people seem not to feel aggrieved at a lack of representation in their parliament. That’s because the system means that their political views are encompassed; there is always someone of the same stripe to whom they can address their problems.

Scotland uses the Additional Member System. It’s very straightforward. There are two votes on the ballot paper. The first is a traditional first-past-the-post. You vote for an individual candidate in an individual constituency. The second vote is for the party, and it applies to a region comprising several constituencies. The regional seats are allocated from party lists in proportion to the number of votes cast. So every voter has an individual MSP but also a group of regional MSPs who are there to represent them.

It’s not perfect, but it’s better than the Westminster system by a long way. It makes for a more diverse debating chamber. It alters the geography of debate, making it less binary and more inclusive. It leans towards the formation of coalitions and compromise. With a two-party system, dogma too often takes the place of the public good. Consensus makes that less likely. It means taking the longer view and acknowledging the weakness in legislative proposals.

Even politicians acknowledge this. When she was asked about operating within a hung parliament, first minister Nicola Sturgeon admitted that the need to satisfy her opponents had on occasion actually improved the Scottish government’s proposals.

I know we had a referendum in 2011 about changing the voting system. It was a shambles, carried out without rigour or enthusiasm. We really don’t need another referendum. What we do need is a parliament willing to put the interests of democracy ahead of naked, self-perpetuating self-interest.

As my son said: “Wouldn’t it be great if someone came up with a system of governance that worked for everybody?” Wouldn’t it just.