When somebody is murdered and his killer is unknown, the detective's first step is to ask: who had a motive? In classic murder-mystery novels and films, the usual answer was: almost everybody. That's the only way to keep the plot going for 250 pages/90 minutes. But in real life, the suspects are generally few, and pretty obvious. So who killed Chokri Belaid?
It's hard enough to manage a fishery stock sustainably when the fish stay put. Once they start moving around, it's almost impossible. That's why the European Union and Iceland are heading into a mackerel war. It's a foretaste of things to come, as warming oceans cause ocean fish to migrate in order to stay in their temperature comfort zones.
A Chinese survey vessels go into the waters around the disputed islands and Japanese patrol ships tail them much too closely.
The real problem is continental drift: Brussels, the capital of the European Union, is getting further and further away from England. Or at least that is British Prime Minister David Cameron's line.
If North Korea's new leader, Kim Jong-un, wanted to end the brutal and destructive tyranny that his father and grandfather imposed on the country, he would need support from abroad. The military and Communist Party elites who control and benefit from that system would have to be brought round or bought off, and that would require lots of foreign aid and a global amnesty for their crimes. So how would he get the foreigners to help?
Israeli Prime Minister Benjamin Netanyahu was once seen as a right-wing figure. Now he's widely considered a moderate. But it's not Mr Netanyahu who has changed; Israel has.
''Those days are over,'' Frances President Francois Hollande said last month, when asked if French forces would intervene in the war between Islamist insurgents who have seized the northern half of Mali and the Government in Bamako. But the days in question weren't over for very long. Last Friday, France sent a squadron of fighter-bombers to the West African country to stop the Islamist fighters from taking the capital.
The most frustrating part of covering the Lebanese civil war (1975-90) was that after a while there was nothing left to say. Syria is starting to feel just the same. It's horrible, but atrocities are a daily event in all civil wars.
It's as if Paul Newman and Jane Fonda had fled the United States in protest at something or other - they were always protesting - and sought Russian citizenship instead. Americans would be surprised, but would they really care? It's a free country, as they say.
It is not known if the word ''dysfunctional'' was invented specifically to describe the Nigerian state - several other candidates also come to mind - but the word certainly fills the bill.
To begin on a happy note, the world didn't end this year.
Here's an interesting statistic: the second-highest rate of gun ownership in the world is in Yemen, a largely tribal, extremely poor country. The highest is in the United States, where there are almost as many guns as people: around 300 million guns for 311 million people.
Many years ago, when I was young and handsome, a friend inveigled me into taking a small role in a film he was making - a proper film, with a real budget and a commercial release, though mercifully it never got much attention.
They made some progress at the annual December round of the international negotiations on controlling climate change, held this year in Qatar. They agreed that the countries that cause the warming should compensate the ones that suffer the most from it.
It's as if the world's leaders were earnestly warning us that global warming will cause the extinction of the dinosaurs. They've actually been dead for a long time already. So has the Middle East ''peace process''.
You probably haven't given much thought to the problems in Mali, but United Nations Secretary-general Ban Ki-Moon has, and his advice on military intervention in the West African country could be summed up in two words: forget it. Although, being a diplomat, he actually used a great many more words than that.
In other parts of the world, separatist movements are usually violent (e.g. Kashmir, Sri Lanka, the various Kurdish revolts) and they sometimes succeed (South Sudan, Eritrea, East Timor). Whereas in the prosperous, democratic countries of the West, they are generally peaceful, frivolous and unsuccessful.
"There is no middle ground, no dialogue before rescinds this declaration," said pro-democracy advocate and Nobel Peace Prize winner Mohamed ElBaradei.
After the loss of 10 million American lives in the Three-Mile Island calamity in 1979, the death of two billion in the Chernobyl holocaust in 1986, and now the abandonment of all of northern Japan following the death of millions in last year's Fukushima nuclear catastrophe, it is hardly surprising that the world's biggest users of nuclear power are shutting their plants down.
Let's be fair: there does seem to be some sort of pattern here, but it is not very consistent.