This post contains 2.1 book reviews. The two books are The Invisible Hook: The Hidden Economics of Pirates by Peter T. Leeson and The Sea Wolves: A History of the Vikings by Lars Brownworth. The extra 10 percent is two chapters from David Friedman's book Legal Systems Very Different from Ours (not yet published, but freely available in draft here).

The Invisible Hook has the basic premise that many infamous pirate behaviours can be explained in terms of rational self-interest rather than assuming they were all vicious psychopaths. In some cases, their self-interest led to arrangements that are more in line with modern values than those of their contemporaries. I felt like the central thesis of this book was strong, but it could have gotten the point across in a shorter length; it gave wordy explanations of straight-forward concepts and was a bit repetitive between chapters.

Leeson discusses economic themes such as the principal-agent problem (which pirates were mostly free from compared to merchant crews since they didn't have a ship-owner on land to answer to), signalling/reputation (using the jolly roger flag and occasional acts of brutality to encourage most of their targets to surrender without a fight), and responding to incentives (pretending to be recruited against their will to avoid hanging if caught). The Invisible Hook also has a lot to say about pirate constitutions (the Articles that an entire ship would agree to be governed by) and democracy.

The Invisible Hook "covers pirates from about 1670 to 1730" (mainly in the Caribbean) and it takes the following perspective:

Peglegs and parrots aside, in the end, piracy was a business. It was a criminal business, but a business nonetheless, and deserves to be examined in this light.


Since pirates were outlaws, they operated outside the scope of government regulations. To prevent their criminal enterprise from imploding, they regulated themselves instead. Pirate regulations, which were privately and voluntarily adopted, were successful because they were private and voluntary. Pirates had a better idea about the kinds of regulations their ships needed than outsiders did. They knew, for instance, that it was important for them to restrict smoking in the hold but unimportant to ban smoking altogether. Pirates had what economists call “local knowledge” of their particular circumstances and how various rules were likely to affect life aboard their ships.

Probably the strongest part of the book concerns pirate government (with their codes and democracy, at a time when those were rare among legitimate governments). Like any ship, pirate ships had captains:

Many important piratical decisions, such as how to engage a potential target, the method to pursue when chasing a target or being chased by authorities, and how to react if attacked, required snap decision making. There was no time for disagreement or debate in these cases and conflicting voices would have made it impossible to undertake the most essential tasks.
A captain who wielded unquestioned authority in certain decisions was critical for success. But what was to prevent him from turning his power against his crew for personal benefit in the same manner predatory merchant captains did?

However, they had another officer to check-and-balance the captain's power:

The primary “other officer” pirates constituted for this purpose was the quartermaster. The way this office worked is straightforward. Captains retained absolute authority in times of battle, enabling pirates to realize the benefits of autocratic control required for success in conflict. However, pirate crews transferred power to allocate provisions, select and distribute loot (there was rarely room aboard pirate ships to take all they seized from a prize), adjudicate crew member conflicts, and administer discipline to the quartermaster, whom they democratically elected.

Both the captain and quartermaster were elected positions and subject to recall. Leeson quotes James Madison to emphasize the importance of checks-and-balances:

In framing a government which is to be administered by men over men, the great difficulty lies in this: you must first enable the government to control the governed; and in the next place oblige it to control itself.”

In addition to this division of power, pirates also had codified articles spelling out the rules their crew would have to follow. Because the law wasn't on their side, pirates had no outside force they could rely on to maintain order on board. Therefore, it was important that the majority (they took captives, of course, but would not want them to out-number the crew) were there voluntarily and consented to some basic rules. Similar logic influenced pirates' divergence from the slavery of their day:

Pirates took slaves, held slaves, and sold slaves. On the other hand, some pirates displayed significantly more tolerant behavior toward blacks. Upward of a quarter of the average pirate crew may have been black. Many of these sailors were former slaves and at least some of them were treated on equal terms with white sailors in the pirate crews they sailed with. They had equal voting rights in the pirates’ democracy and likely received an equal share of the pirates’ plunder.

One of the key themes of Invisible Hook is that pirates (in general) were neither blood-thirsty sadists nor idealistic egalitarians, but were responding relatively rationally to the realities of their situation. For example, they had more free Africans on their crews than merchant ships did; according to the author's interpretation, this was not because they were persuaded by the appeals of abolitionists but because having people on their ships who didn't want to be there carried a risk and unlike on merchant ships the proceeds of slave labour would have been dispersed among the entire crew instead of to a single owner. Similarly, pirates had to limit their use of conscription.

Something that stands out to me is how short the golden age of piracy was—basically a single life-time—and how the number of sailors involved was not actually that great. In the waning decade of the period, around 400 people were executed as pirates (out of perhaps a couple thousand who were involved so the majority either weren't caught or got away with lesser penalties):

between 1716 and 1726 some four hundred pirates were hanged—an average of forty sea dogs per year. Eighty-two of these executions came in 1723 alone, a strong indication government’s bolstered antipiracy efforts, in full swing by the early 1720s, were having the desired effect.

For a relatively small group, pirates still loom large in the imagination. And some of the key structures they used to promote order and cooperation in their ship-board societies (e.g. division of power) are more common now than they were in their own day.

Sea Wolves was a pretty quick read on the history of Vikings—mainly on the "sea kings" who went off raiding (or trading or exploring), sometimes over remarkable distances, and less on the societies that spawned them. In contrast to the book that I reviewed in my previous post, this book was a pretty linear (divided by region) narrative.

As a narrative, Sea Wolves tends to focus on some prominent men and women in history, both Vikings and people that fought against them. I got the impression that good leadership was very important, since a kingdom might suffer repeated raids from a Viking sea king then in the next generation the tables would turn. Here are some of the people who stood out the most:

  • Charlemagne (d.814): During his life, his empire was too powerful to be much of a target for raids.
  • Ragnar (d.865): This legendary Viking had even more infamous sons, who led the Great Heathen Army that conquered a substantial portion of England in the 9th Century.
  • Alfred the Great (d.899): This king of Wessex was one of the most successful Anglo-Saxon kings at resisting the Vikings.
  • Hrolf/Rollo (d.930): He was known as Granger (the walker) because he was too big to ride a horse. The king of France made a treaty with him to settle in Normandy, protecting it from raids by other Vikings.
  • Olga (d.969): She was a ruler of Kiev. After her husband was killed, she burned a town to avenge him. Later, she converted to Christianity.
  • Vladimir (d.1015): A grandson of Olga who, like her, converted to Christianity. He made all of Kiev convert with him.
  • King Cnut (d.1035): He ruled over a territory (only united during his lifetime) covering Denmark, Norway, and England and various islands around the North Sea.
  • Harald Hardrada (d.1066): He's called the last Viking by the author. He was a mercenary in Byzantium, a king in Norway, and died invading England.

Sea Wolves is divided into four sections: Raiders, Explorers, Traders, and Homelands. The first section is about the Danish and Norwegian Vikings who raided along the Frankish coast and the British Isles. Prior to their raids, the 8th century had peace and stability (thus monasteries being filled with treasures from donors and pilgrims). Raiding evolved into obtaining territory: in Normandy, northern England, and Ireland (York and Dublin were actually important Viking cities at one time). As warlords turned into kings in Scandinavia, some norse found the government too restrictive and set out for fresh territory, discovering and settling Iceland and Greenland and even briefly trying to establish a settlement in North America. Vikings from Sweden went the opposite direction, trading—and taking slaves—up and down the rivers of western Russia. They became a ruling caste of Kievan Rus. The Volga took them to the Caspian Sea and the Dniepr took them to the Black Sea and Constantinople, which they attacked a few times (see here) and ultimately got hired on as an elite mercenary corps (the Varangian Guard). The final section is about the transition of the Viking homelands from places where ambitious men could go off raiding and become sea-kings to more centralized kingdoms (King Cnut, for example, was treated practically as an equal to the Holy Roman Emperor).

Lars Brownworth discusses a few factors for why the Vikings were able to go so far and have such an impact from a small and remote population base. Their ships, swords, and organization all gave them an edge:

What made the great Viking raids possible was a revolution in shipbuilding at the end of the eighth century. The earliest Viking vessels were copied from Roman or Celtic designs and powered by oars instead of the usual paddles. Like all ships of the time they were slow and prone to capsizing in rough seas, appropriate for short trips that hugged the shore. Sometime in the eighth century, however, the Vikings invented the keel. This simple addition is among the greatest of nautical breakthroughs. Not only did it stabilize the ship, making it ocean-worthy, but it provided a base to anchor the mast. A massive sail, some as large as eight hundred square feet, could now be added as the major source of propulsion. The impact was immediate and stunning.


Viking longships lacked the keels of the larger ocean-crossing ships, and their relatively shallow drafts allowed them to be beached virtually anywhere instead of just the deep-water ports required by other vessels. This made it possible for a longship to navigate up rivers, and some were light enough to be carried between river systems.

The advantage in speed (compared to defending armies travelling by road) was remarkable:

[A] fleet in Scandinavia could cover the nine hundred miles to the mouth of the Seine in three weeks, an average of over forty miles per day. Under oar they were nearly as fast.


The medieval armies they faced, assuming they had access to a good Roman roads, could only average between twelve and fifteen miles per day. Even elite cavalry forces pushing hard could only manage twenty.

Viking swords were also state-of-the-art:

The one exception to this general inferiority [of equipment] was Viking swords. The original design was probably copied from an eighth century Frankish source, a blacksmith named Ulfberht whose name soon became a brand. The Vikings quickly learned to manufacture the blades themselves, and weapons bearing the inscription Ulfberht have been found all over Scandinavia. They were typically double edged, with a rounded point, made of multiple bars of iron twisted together. This pattern welding created a relatively strong and lightweight blade that could be reforged if broken. They were clearly among a warrior's most prized possessions and were passed down as heirlooms and given names

Another advantage was their flexible organization:

Aside from their swords, the Vikings’ main advantages lay in their sophisticated intelligence gathering and their terrifying adaptability. They had advance warning of most Frankish military maneuvers, and could respond quickly to take advantage of political changes. Most formidable of all, was their malleability. ‘Brotherhoods’ of dozens or even hundreds could combine into a larger army, and then re-dissolve into groups at will.

(This certainly has parallels with pirate organization discussed above; I'm also reminded of some of the discussion of organizational effectiveness in a book on monastic orders I read a couple of years ago).

Countering these advantages took a lot of effort on the part of Vikings' targets. Here are some reforms that Alfred the Great made to resist them more effectively:

The Vikings’ mobility had been the key to their success, so Alfred took it away. Towns, bridges, and roads were fortified, and strongholds were built throughout Wessex to deny roving bands any sanctuary. Within fifteen years, the kingdom was bristling with fortresses allowing the English to strike at any future raid from numerous points. Next, Alfred reorganized the army, training a professional, permanent force supported by taxes, to replace the unreliable peasant levies. He even attempted to challenge the Viking monopoly of sea power by beginning work on a fleet, although the results proved disappointing. To stabilize things internally, he also reformed the currency.

He also insisted on literacy for his commanders so that they could receive written orders.

The Viking era lasted for a few centuries, but it re-shaped the map of Europe:

It was the Vikings who exposed the sprawling empire of Charlemagne, revealing fundamental flaws in the organization of that would-be-Roman Empire. As it broke apart under the hammer blows of the Vikings, the survivors were forced to create smaller, more efficient states. Out of the ashes of the Viking assault rose the four great medieval powers of Western Europe: France, England, The Holy Roman Empire, and the kingdom of Sicily. All four of these were direct products of the Viking age, and three of them were founded or consolidated by Viking descendants.


At the same time, Viking traders in the east were establishing the market towns and trade routes with Byzantium that would bring Roman institutions far beyond the borders of the ancient Roman empire. The centralized states that they founded would eventually develop into what is today the Ukraine, Belarus, and Russia.

(Apparently "town names that end with -bec in France or -by in England" were named by Vikings).

In the Norman invasion of England in 1066, all sides were led by people of Viking descent. Harold Godwinson (whose mother was Danish) defeated Harald Hardrada at the Battle of Stamford Bridge but then was defeated himself by a Norman duke descended from Rollo.

During the Viking era, the region gradually converted from paganism to Christianity. Sea Wolves discusses the conversion of several rulers. Interestingly, most of the conversions in the book (at least on the part of the rulers) were not at the point of a sword but to seal marriage, trade, or political alliances. Vladimir (of Kievan Rus) was a typical example:

The conclusion to which Vladimir came – to convert to Christianity – was the realization that he could accomplish far more as an ally of Constantinople than as a Viking sea-king. With that step, he spiritually and culturally cut the ties with his Viking heritage.

Lars Brownworth surmises that contact with Byzantium may have motivated Vladimir (and a similar story could apply for Danish and Norwegian rulers in contact with the Holy Roman Empire) to also have a society with only a single God—and only a single king. Whatever the motivation, however, there were numerous positive effects:

A cynical observer, and there were many of them in Vladimir's time, would say that his conversion was purely a political move, but, strange as it may seem, he appears to have been genuinely changed. The man who had raped his own sister-in-law now organized daily food drives for the ill and destitute. He laid out his own table for the sick, and when told that some were too ailing to make it, he arranged for wagons of bread, fish, vegetables, and mead to be taken to them. He dismissed his non-Byzantine wives and his small army of concubines, and ironically – considering the amount of blood that he had spilled – abolished the death penalty. Schools were founded in several cities, and a part of each year's tax revenue was set aside for alms.

One of the biggest changes was the cessation of the Viking slave trade:

Slavs, who were no longer seen as targets to be raided, but as Christian subjects to be protected.

On the subject of Vikings, here is a game and a study about them that I came across recently.

The chapters that I read in Legal Systems Very Different from Ours complement the two books reviewed above. They concern legal and economic structures among Icelandic society and among pirates.

Friedman describes how Icelandic criminal law was similar to current tort law:

In saga-period Iceland a thousand years ago, if you killed someone his relatives sued you. Studying that system was what first got me interested in the broader subject of this book.

Like Sea Wolves, Friedman's chapter on Iceland describes how it was settled by people who found living under a king too stifling:

In the latter half of the ninth century, King Harald Fairhair unified Norway under his rule. A substantial number of the inhabitants, unhappy with the change, left; many went either directly to Iceland, which had been discovered by the Norse a few years earlier, or indirectly via Norse colonies in England, Ireland, Orkney, the Hebrides, and the Shetland Islands. The political system they developed there was based on Norwegian traditions with one important innovation–there was no king. The relationship between the Icelandic godi and his thingmen (thingmenn) was contractual but not territorial. The godi had no claim to the thingman's land and the thingman was free to transfer his allegiance.

Icelanders were very independent; the legal system they used didn't come with much bureaucracy.

Penalties imposed by Icelandic courts were either outlawry or wergeld (payment for taking a life):

The function of the courts was to deliver verdicts on cases brought to them. That done, the court was finished. For serious offenses, conviction meant full outlawry. The outlaw’s property was confiscated, part going as a damage payment to the victim or his heirs, part to support the outlaw’s dependents. If more was available, ... . It was legal to kill an outlaw, illegal to feed him, shelter him, or help him to leave Iceland. For somewhat less serious offenses, conviction meant lesser outlawry. A lesser outlaw had the right to leave Iceland and could return in three years. For still less serious offenses the punishment was a fine. ...
Prosecution was up to the victim or his survivors. If they and the offender agreed on a settlement, the matter was settled. Most cases in the sagas were settled out of court, usually for money damages, sometimes for lesser outlawry or greater outlawry with permission to leave Iceland. Many were settled by arbitration, including the two most serious conflicts that arose prior to the final period of breakdown in the thirteenth century. Calculations by two different scholars suggest that only about a tenth of cases went to a final judgment by the court.
Where a clash resulted in deaths on both sides they were usually set off against each other, sometimes weighted by how important the man killed was, with the excess paid in wergeld or outlawries. In some cases part of the payment for killing one man was the cancellation of the outlawry imposed on another in a previous conflict.

Friedman includes a table that shows wergeld owed for crimes against people at different levels of society, calculated in terms of wages and cloth production.

He seems to think the system was well-balanced at first, until power got concentrated in too-few hands:

One cause of the breakdown of the Icelandic system seems to have been increased concentration of wealth and hence power. By the Sturlung period there were many areas where all or most of the godord were held by one family, reducing or eliminating the ability of the individual thingman to choose his godi and creating a de facto, if imperfect, form of territorial sovereignty.

In the chapter on pirates, I found Friedman covered a lot of the same concepts in a much more concise manner than The Invisible Hook did (and since his chapter is available for free, I'd recommend reading it if the topic interests you). At least one of his articles is cited in that book, so he may have even inspired some of the ideas it contains. He frames the same dilemma that pirates would face in maintaining order on board:

Successful piracy required the cooperation of a sizeable pirate crew. The average Caribbean pirate ship was crewed by 80 men, and the largest crews consisted of several hundred. This raises the question of how pirates, who, as criminals, could not rely on government to provide their crews law and order and had no compunction about murdering and stealing for private gain, managed to cooperate with one another to engage in piracy.

Pirate crews were much larger than merchant crews for the same size vessel (giving them an advantage in a fight, but making any on-board conflict more of a risk).

Like Leeson, Friedman discusses pirate articles and the roles of captain and quartermaster, along with pirates cultivating a reputation for brutality to discourage resistance and pretending to be conscripted when they'd actually joined voluntarily. So he covers much of the same ground (but obviously doesn't have space to expand on things as much).