Mark rightly gives points to Gordon Brown for providing arguments for Scotland to stay in the Union (as it in the end chose to do) based on principle and sentiment, not merely interest. Contrast the absence of Tony Blair, junketing with Davos Man (or worse) and Menton Girl  somewhere sunnier than Scotland. Brown’s argument was based on shared battlefields and domestic glories like the NHS rather than Hume and Hutton. But it was fair of Mark to say that it reflected the cosmopolitan, outward-looking values of the Scottish Enlightenment. Its leading lights, apart from Burns, were SFIK all Unionists and anti-Jacobites. The mathematician Colin McLaurin actually supervised, though unsuccessfully, the defence of Edinburgh against the Jacobite army rampaging its way south. The Scots’ combination of physical courage, industry, and respect for learning have made the world their oyster.

So here’s a small salute to the whole gang, represented by Adam Smith, Professor of Moral Philosophy at Glasgow University. (Scotland had four universities by 1600 to England’s two). His best known sentence must be this, from Book I, Chapter 2 of The Wealth of Nations:

It is not from the benevolence of the butcher, the brewer, or the baker that we expect our dinner, but from their regard to their own interest.

(The website is libertarian. They might try reading a bit more of him; he isn’t Rand at all.)

Perfectly illustrating the point, here’s very nice and cheering photograph of Mr. Edward Buta’s flourishing solar shop in Katoro, Tanzania (pop. 11,925). (H/t Tim McDonnell at Mother Jones.)

Tanzania is a very poor country; GDP per head is $1,715 (Wikipedia), presumably lower in the countryside. Many of Mr. Buta’s customers in the villages must be living off $5-$10 a day. The electricity grid stops in the towns, and there isn’t the money to expand it to the villages in non-geological time. But electricity is so valuable, for phone charging and lighting, that very poor people will cough up for small solar kits.

Nobody here is acting out of altruism. As Smith says, self-interest is dependable. Charity aid workers come and go, but Mr. Buta will be in his shop next week and next year, as long as it still pays. But he’s pretty safe. The gear will get better and cheaper, with learning and economies of scale. What’s next? Bigger setups to run TVs and fridges, I would guess. Somebody will market a fridge with high thermal inertia, that can stay cool overnight. A better-capitalised competitor like WalMart may muscle in and grab his market. That’s capitalist life, and could happen in any business.

The off-grid solar market in rural Africa, on this evidence, is now self-sustaining. Governments can kill it by interfering, through tariffs, domestic content rules or red tape. If they leave well alone, it will do fine. Score a big one to Adam Smith.

Wait a minute, though. The story fits the paradigm of enlightened self-interest reasonably well, but not that of laissez-faire. Consider some of the critical steps in the history of solar power.

• 1954: Invention of photovoltaic cells at Bell Labs. AT&T was a profit-making corporation, but running a great institute of blue-sky physics can’t be explained by self-interest. Prestige? Noblesse de monopole oblige? Directorial whim?
• 1950s-1960s: The Pentagon and NASA provide a niche, high-price market allowing commercialisation and small-scale industrial production.
• 1970s-1980s: Following the first oil crisis in 1973, MITI in Japan support development of panel systems for general use (Sunshine Programme); $6bn a year in the 1980s.
• 1991-2014: Germany adopts EEG law in 1991, offers high 20-year feed-in tariffs for solar power from 2000. Installation boom from around 2005. Legacy liability of solar FITs to expiry over $100bn.

Mr. Buta and his customers should give thanks to Jean-Baptiste Colbert’s interventionist principles as well as to those of Adam Smith.