Quiz 9 · Weighing Evidence and Reasoning — Ancient America to the Singularity

Who made this?

1. Who made it?: Maya scribes, several of them: the handwriting changes from section to section, and scholars count six or eight different hands. No name is written anywhere in the book. They painted on bark paper made from fig-tree fiber, coated with a thin layer of lime plaster so the surface would take ink, in black and red with some blue, green, and yellow.
2. When, and where?: The library that holds it dates it to the late Postclassic period, about 1300 to 1521, and places it in the north or northeast of the Yucatán Peninsula, probably copied from an older book of the Classic period. Other scholars put it earlier, in the 1100s or 1200s. It is thirty-nine leaves painted on both sides, about 3.56 meters (nearly twelve feet) long when opened, folded like an accordion.
3. Why, and for whom?: For the priests who kept the calendar. The book holds tables of the movements of Venus, tables for predicting eclipses, almanacs for deciding which days were good or bad for planting and other work, and pictures of the gods who ruled those days. It was a working book, consulted and reconsulted, not a book for display.
4. Who has it now, and how did it get there?: The Saxon State and University Library in Dresden, Germany, where it has been since 1739. That year the library’s director, Johann Christian Götze, passing through Vienna, got it from a private person whose name he did not record, and wrote that he had it “for almost nothing,” as “a Mexican book.” How it reached Vienna is not recorded; the usual guess is that it went to Spain in the 1500s, and a guess is what it is. Nobody recognized it as a Maya book until 1853. In 1945, in the bombing of Dresden, water got into the cellar where it was stored and damaged its edges. The library now describes it as “a cultural asset from a colonial context” and says it is researching where the book came from. Only four Maya books survive; Spanish priests burned the rest in the 1500s.
5. Whose voice is missing here, and where can we hear it?: The scribes’, and the priests who read the book: no name, no city, no reader is recorded, and Götze’s three sentences on where he got it are all the record there is. The living voice is easier to find than the record. Several million people speak Maya languages today, and Maya scholars in Mexico and Guatemala now read these glyphs, which no one could read in 1739. Quiz 65 takes up the Maya at full size, and Quiz 72 takes up how we know.

For your notebook: Götze wrote that he got the book “for almost nothing.” Who lost something in that bargain, and what evidence would it take to say?

Sources: SLUB Dresden, the library’s own pages on the Maya codex (provenance and acquisition; origin; material and conservation), quoting Götze’s 1743 catalog; Library of Congress, World Digital Library entry for the Dresden Codex; Reddick’s translation of Förstemann’s 1880 introduction (Mesoweb).

First, the idea

A claim is a sentence that could turn out to be false: the city was abandoned in a single year. Evidence is what a stranger could check that makes the claim more likely or less: a date carved in stone, a count, a document, a layer of mud in a lake bed. Reasoning is the set of steps that gets from the evidence to the claim. The test asks you to judge all three: is there evidence, does it fit the claim, and do the steps hold.

Show me the receipt. When someone says a thing was paid for, the receipt is the slip a stranger could check: the store, the date, the amount. Evidence is a claim’s receipt. A claim without one may still be true, but you cannot know that from the claim. And a receipt for a different purchase is no receipt at all: evidence that fits a smaller claim does not pay for a bigger one.

Four checks, in order. Is there a receipt? A confident voice, a famous name, or a crowd that agrees is not evidence; it is someone else’s claim. Does the receipt match the claim? “No one lives here now” is evidence about now, not about a thousand years ago. “Forty riders on one train” is evidence about that train, not about the city. Could the same receipt pay for a different claim? A drought and a decline in the same century fit “the drought caused the decline,” and also fit “both happened, for separate reasons.” Quiz 7’s rule holds: same time is not the same as because. Do the steps hold? The step that fails most often is the one from silence to absence: no written record, so nothing happened; no one here, so the people are gone. A silence is a fact about the record, not about the world.

When the test gives you two accounts, it is rarely asking which one you believe. It asks which claim has evidence behind it, which account a reader could check, and what a particular piece of evidence does and does not show.

Worked example — thinking out loud

The passage is short. I read it, then I ask for the receipt on each sentence.

1The Maya calendar ends on December 21, 2012. 2Ancient Maya priests predicted that the world would end that day. 3Scientists at NASA were asked about it thousands of times. 4So many people cannot all be wrong.

Written for this example, after the way newspapers wrote in 2012.

My first pull is sentence 1. It sounds like a plain fact, and it is half of one. The Maya count of days does reach a round number that day, the way a car’s odometer rolls from 99,999 to 100,000. The odometer does not end; it turns over. A cycle completing is a fact; “the calendar ends” is a claim laid on top of it, and the receipt only covers the fact.

Sentence 2 is the big claim, and I ask what evidence there is that priests predicted an end. Scholars know of one carved text that names the date, from Tortuguero, in Tabasco, Mexico (a second was reported in 2012 at La Corona in Guatemala); it is broken, and what can be read says a god will be present or will descend on that day. That is a receipt for “one monument names the day and a god,” not for “the world ends.” Sentence 3 is true and does no work: being asked a question thousands of times is evidence that people were worried, not evidence about the calendar. Sentence 4 is the step from a crowd to a fact. A crowd can be wrong; the count of believers is not a receipt for the belief.

So the passage has one fact, one claim the evidence does not cover, one idle truth, and one bad step. On the test that becomes: which sentence is best supported by evidence? Sentence 1, and only its first half. Which sentence is an opinion presented as fact? Sentence 2. Keep the four checks in that order and the questions answer themselves.

Part A · The skill by itself

1. A student writes: “Around 1100 CE, Cahokia was the largest city north of Mexico.” Which of the following is evidence a reader could check?

The student is completely sure of it. A published archaeological survey that measures the settled area and estimates the population, with its method stated. Cahokia is an impressive place to visit. Everyone in the class agreed with the sentence.

2. “No written records made by the Lenape before 1600 survive. Therefore the Lenape had no history before 1600.” What is wrong with this reasoning?

The first sentence is false; many such records survive. It steps from “no written record” to “no history,” but a people keep history in other ways, in what they say, make, and name; the silence is in the paper, not in the past. Nothing; without documents there is no history. The date should be 1500.

3. A reporter counts 40 riders on one subway car at 8 a.m. on a Monday; 30 say they are going to work. She writes: “75 percent of New Yorkers ride the subway to work.” What is the fault?

The arithmetic is wrong. The evidence is 40 riders on one car at one hour; the claim is about eight million people, most of whom were not on that car, and many of whom were not on any train. Reporters are not allowed to count people. She should have written 70 percent.

Part B · The skill in the wild

Two accounts of the same thing: what happened to the great Maya cities of the southern lowlands after about 800 CE. The questions are about evidence and reasoning, not about which account you like.

Account A · after the travel books of the early 1900s

1The forest around the great city is silent; trees grow through the doorways of its temples. 2No one has lived here for a thousand years. 3The people who raised these stones vanished, all at once, and no one knows why. 4Some say a plague carried them off; some say they angered their gods.

Account B · after the research of the last thirty years

5In the cities of the southern Maya lowlands, the practice of carving dates into stone monuments stopped, city by city, between about 800 and 910 CE; the last such date known is from Toniná, in 909 CE. 6Sediment cores taken from Lake Chichancanab in Yucatán (published 1995) and from the sea floor of the Cariaco Basin off Venezuela (published 2003) show several severe droughts in those same centuries. 7Many scholars think the droughts were one cause of the cities’ decline, alongside war between cities and the strain of feeding large populations; others point out that most of the drought evidence comes from the north, where the decline was milder, and that the cities emptied over about 150 years, not at once. 8Cities in the north, such as Chichén Itzá and later Mayapán, went on for centuries, and Maya people number in the millions today in Guatemala, Mexico, Belize, and beyond.

Both accounts were written for this quiz. Account A follows the way travel writers and guidebooks described Maya cities in the early twentieth century. Account B follows Hodell, Curtis, and Brenner (Nature, 1995), Haug and others (Science, 2003), Gill and others (Ancient Mesoamerica, 2007) for the monument dates, and Douglas and others (PNAS, 2015) for the disagreement about where the drought evidence comes from.

4. Which sentence in Account A reports something the writer could have seen?

Sentence 1 Sentence 2 Sentence 3 Sentence 4

5. Account A moves from the silence of the forest (sentence 1) to the claim that the people “vanished” (sentence 3). What is wrong with that step?

Forests are never silent. An empty city today is evidence about today; it says nothing about whether people left slowly or all at once, or where they went, and sentence 8 shows they did not vanish. The writer should have said the city was two thousand years old. Nothing; an empty city proves its people are gone.

6. By itself, what does the drought evidence in sentence 6 show?

That drought caused the cities to decline. That severe droughts happened in the same centuries as the decline; whether they caused it is a further step, taken in sentence 7 and argued there. That the Maya had no way to store water. That the lakes were the cause.

7. Which claim in Account B could a reader check most directly?

That the droughts were one cause of the decline That the last carved date in the southern cities is from 909 CE, since the date is cut in stone and can be read That feeding large populations strained the cities That the cities were at war with one another

8. Complete the sentence so that it matches the lesson.

A claim with no evidence behind it is [false / unproven, whether or not it turns out to be true / an opinion, which is as good as a fact], and evidence that two things happened at the same time shows [that one caused the other / that one may have caused the other, which still has to be shown / nothing at all].

The key — and why the tempting answers tempt

1. B. A survey with its method stated is something a stranger could check: how the area was measured, how the population was estimated, and against what. A and D are the same trap in two sizes: one confident person, then a room of them. Agreement is a fact about the room. C is true and does no work.

2. B. The step from silence to absence. Paper is one way to keep a past; the Lenape kept theirs in speech, in objects, and in the names of places, many of which the city still uses. C is the fault stated as a rule, and it would erase most of the world’s history before writing. A denies the evidence instead of examining the step.

3. B. Thirty of forty is 75 percent; the arithmetic is fine. The fault is size: a claim about all New Yorkers needs evidence about New Yorkers who were not on that car, at that hour, on that line. A is the trap for students who expect every numbers question to be a math error. D changes the number without fixing the step. Quiz 10 takes the percent up properly.

4. A. Silence and trees in doorways are what a visitor sees. Everything after sentence 1 is a claim about the past, which the visitor could not have seen. Sentence 3 is the most vivid, and vividness pulls; it is also the least supported. Sentence 4 reports what “some say,” which is other people’s claims, not the writer’s observation.

5. B. A silent city is a receipt for “no one lives here now,” nothing more. “Vanished” claims a manner of leaving and a fate, and sentence 8 contradicts the fate outright. D is the step itself, stated as if it were obvious; it is the same step as item 2, in a forest instead of an archive.

6. B. Cores from a lake and from the sea floor record rainfall; they show that severe droughts happened then. Cause is a separate claim, and Account B is honest that scholars argue it. A is the trap Quiz 7 built the lesson around: same time, so because. Notice that sentence 7 does the careful thing: it names the drought as one cause among several, and names the people who doubt it.

7. B. A date carved in stone is the most checkable kind of evidence on the page: it can be photographed, read, and read again by someone else. A, C, and D are all interpretations, reasonable ones, that rest on other evidence not shown here. The question asked which claim, not which is most important.

8. unproven, whether or not it turns out to be true; that one may have caused the other, which still has to be shown. The first is the receipt rule: no receipt, no purchase shown, even if the purchase happened. The second is Quiz 7’s rule stated as evidence. “False” overreaches the other way; a claim with no evidence is not thereby false. “Nothing at all” throws the evidence away, and Quiz 2 says never do that.

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