Today we're going to learn about the post hoc ergo propter hoc fallacy. This is a fallacy in reasoning which holds that just because event B occurred after event A that event B was caused by event A. This usually doesn't stand up to scrutiny but it is, nevertheless, the historian's favorite fallacy.

Case in point. I recently watched 'Sinking Atlantis' on Secrets of the Dead which was on PBS. The thesis of this show is a good example of this fallacy. You can watch the whole thing yourself here:(video dot pbs dot org slash video slash 1204753806).

That thesis is quickly stated. Sometime in the 17th century BC a giant volcano on the island of Thera in the Aegean sea blew up in a catastrophe like (some say even larger than) Krakatau in Indonesia. This caused a huge tsunami which devastated the coast of Crete and so weakened the Minoan civilization as to leave it easy prey for the Achaean Greeks. Let's look at the probabilities.

Thera exploded in a giant volcanic cataclysm in 1628 BC.  Probability: 1.0.  We know that this happened.

This explosion caused a giant tsunami. Probability: 0.99. We're very sure that this did happen and as the scholars on Crete and other places in the Aegean continue their work the probabilities will converge on 1.0.

This explosion sank every ship in the Aegean: Probability: 0.75. There had to have been a significant cost to Aegean shipping . The reason that I mark this down to 0.75 is that the Aegean is a complicated place with hundreds of islands that would have acted as a damping function on any tsunami pulse (although not the north coast of Crete). Also, any ship that wasn't close to land may have survived. I can certainly agree that the effect on shipping would have been significant and even devastating if any given ship was close to land. But there are no tsunamis at sea. A tsunami is a pulse, not a wall of water. As that pulse reaches shore it becomes a wall of water. Thus ships closer to land are in the most danger. This does include the north coast of Crete which faces Thera.

This explosion caused wide-spread devastation on the coast of Crete. Probability: 0.5 (random, a guess). There were some areas that were affected by tsunamis and this is the strongest part of the show. Specifically they name the Minoan centers of Mallia and Palaikastro. I've never been to Palaikastro but I have stood on the shore at Mallia and I can easily imagine that a very large tsunami would do a great deal of damage to the Minoan town there, even destroy it completely. Today Mallia sits on a level plateau about 20 to 30 feet above the water line. This would have been less in Minoan antiquity. We know, however, that Knossos was not affected by the tsunami; it's too far inland.

This explosion and consequent tsunami destroyed or severely weakened Minoan civilization so as to leave it weak prey for the Achaean Greeks: Probability: 0.0. We know that this did not happen.

Why doesn't the Thera volcano or any consequent tsunami explain the weakening or collapse of the Minoan civilization? Well, first of all, the dates don't work. The Thera eruption occurred in 1628 B.C. (In their foggy and imprecise way the producers of this show refer to that eruption as sometime 'after' 1600 B.C.) This is one of the few hard dates we have in all of Bronze Age studies. We know this with some accuracy because it's proved in two completely different ways, ice core samples and dendrochronology. That these two different technologies agree makes the date 1628 B.C. something that you can take to the bank.

It seems clear that, about 1450 B.C., Achaeans from Greece invaded Crete and began the reduction of the island. The show is right to say this. What the show doesn't explain is why, if the Thera eruption fatally weakened Minoan civilization in 1628 B.C. it took the Achaeans nearly 200 more years to get their act together enough to conquer Crete. Two hundred years is a long time. This is at least eight generations and a lot of changes can occur in that time.  Even the United States itself is only about 230 years old. One of the weak spots among those who, like Bronze Age specialists, think in centuries is that they end up by thinking that a century is an insignificant span of time. It isn't. An agricultural society like the Minoans could have easily rebuilt its cities and population in much less time than two hundred years. We know that because they'd already done it. In about 1750 BC all the palaces on Crete were burned and destroyed (we don't know why). They were immediately rebuilt by the Minoans in forms bigger and better than they had been before.

William Jennings Bryan was no historian but he expressed an essential insight when he said this in his famous Cross of Gold speech(1896):

“I tell you that the great cities rest upon these broad and fertile prairies. Burn down your cities and leave our farms, and your cities will spring up again as if by magic. But destroy our farms and the grass will grow in the streets of every city in the country.”

To say that the Thera eruption and tsunami caused the destruction of Minoan civilization by the Greeks is a picture-perfect suitable-for-framing example of the post hoc ergo propter hoc fallacy with which I began this post.

And what does it mean to say that Minoan civilization is fatally weakened? To kill 100,000 people? 250,000? One million? Does that constitute a weakening (on what's probably an already over-populated island?) After the Black Death of1348 killed a third of its population Europe blossomed. To destroy one town? Two towns? All the towns? In an agricultural society like Minoan Crete? In order for Minoan civilization to collapse it would take a lot more than the destruction of their cities. The strength of the Minoans didn't lie in the cities but in the countryside; specifically in the Mesara which is a valley, about five miles wide, that stretches from the ocean near the modern-day site of Hagia Triada inland about 30+ miles. This fertile plain, still intensively farmed, was the heart of Minoan prosperity and wealth. It formed the support infrastructure for their cities and it provided the goods which these famous traders shipped overseas.  If the volcano had destroyed that then Minoan civilization would have collapsed. But that didn't happen; the Mesara is on the other side of the island.

Weakened Minoans or not, why did the Achaeans invade Crete in the first place? What did they have against the Minoans? Was it trade friction? Possibly. Were the Achaeans looking to expand into the fertile island of Crete because of population pressure in the Peloponnese? Possible. Had the Minoans wiped out some errant Mycenaean colony on Crete or the Cyclades thus creating a casus belli? Was it a religious war, a crusade?   Did some mad Mycenaean prophet tell the Achaeans that invading Crete was their manifest destiny? Was it a dynastic marriage alliance gone wrong? Was there a civil war on Crete in which the Mycenaeans were invited in as mercenaries? We don't know. We'll never know (see previous post). But that's not the same thing as ignoring all possibilities except for that naughty volcano.