Scott Alexander once wrote:

David Stove once ran a contest to find the Worst Argument In The World, but he awarded the prize to his own entry, and one that shored up his politics to boot. It hardly seems like an objective process.

If he can unilaterally declare a Worst Argument, then so can I.

If those guys can unilaterally declare a Worst Argument, then so can I. I declare the Worst Argument In The World to be this:

“A long time ago, not-A, and also, not-B. Now, A and B. Therefore, A caused B.”

Example: In 1820, pirates were everywhere. Now you hardly ever see pirates, and global temperatures are rising. Therefore, the lack of pirates caused global warming.

(This particular argument was originally made as a joke, but I will give some real examples later.)

Naming fallacies is hard. Maybe we could call this the “two distant points in time fallacy”. For now I’ll just call it the Worst Argument.

The Worst Argument is a special case of the post hoc ergo propter hoc fallacy: “A happened before B, therefore A caused B.”¹ I find this special case to be particularly bad. Post hoc ergo propter hoc can make a bit of sense sometimes: maybe B happens immediately after A, maybe A and B repeatedly appear together. That doesn’t definitively establish causality, but if you have data showing that B always comes right after A, I want to hear about it.

The thing about the Worst Argument is that it provides almost no evidence of anything. You can’t just look at two distant points in time, check one independent variable, and assume that the independent variable explains the dependent variable. So many other things could have happened! It’s an incredible leap to say that the rise in global temperatures must be caused by the decline in pirates when about one zillion other things changed between 1820 and today.

The Worst Argument is the worst version of post hoc ergo propter hoc because:

1. It only looks at two data points.
2. The two data points are far apart in time.

If you’re going to base your reasoning on post hoc ergo propter hoc, at least give me a bunch of data points! Or at least make them be close together in time!

The Worst Argument so obviously bad that surely no one would ever think to invoke it, and if invoked, surely no one would take it seriously, right? And yet people make arguments of this form all the time. And I’ve been persuaded by arguments like this! The fact that this fallacy keeps fooling people (including me) makes it my choice for Worst Argument In The World.

Let me give some real-world examples. These statements aren’t all wrong, but the arguments are all bad. (It’s possible to make a fallacious argument in support of a true conclusion.²)

School uniforms prevent crime

When I was in 9th grade, I spent a lot of time on debate.org, a (now-defunct) website that hosted online written debates. I participated in a debate on the proposition “School uniforms ought to be worn in primary and secondary schools.” I took the negative. My opponent was one of the most renowned debaters on the site, with a record of 75 wins to 7 losses. I was a little nervous to go up against him and I wanted to do my best.

The debate lasted for three rounds. After the first two rounds, I felt like I was losing, and I spent hours poring over my opponent’s arguments to figure out how to write my final rebuttal. At some point, I had an epiphany: I realized that his central argument was flimsy, but his rhetoric was so good that I hadn’t noticed.

His argument was essentially this:

1. In 1993, the Long Beach school system did not require uniforms, and it had high rates of school crime.
2. In 1993, it required school uniforms, and it had dramatically lower rates of crime.
3. Therefore, school uniforms must have caused the reduction in crime.³

Nothing else pertinent could have possibly happened in those 6 years, right? They couldn’t have instituted new policies for handling troublesome students, or changed their rules for reporting crimes, or anything like that. It could only have been the school uniforms.

In my final rebuttal, I focused on emphasizing the badness of this argument. It was enough to persuade the readers, and I am happy to say that my opponent now has 8 losses.

Franklin D. Roosevelt solved the Great Depression

An argument that I believed for a long time:

1. The Great Depression started in 1929.
2. FDR was elected in 1931.
3. The Great Depression ended in 1939, while FDR was in office.
4. Therefore, FDR solved the Great Depression.

Plenty of other things happened between 1931 and 1939. An economy can shift quite a lot in 8 years, for many reasons other than who’s president. A typical economic cycle only lasts something like 8 years, and the typical recession only lasts one or two years. After that long you’d expect the economy to look very different, no matter who the president is.

You might say, hey, aren’t there better arguments about how specifically FDR’s policies could have improved the economy? Yeah, there are, but that’s not why I used to believe FDR had great economic policies. I believed it because I fell for the Worst Argument In The World.

(Folks on the other side of the political spectrum like to say Reagan solved the economic problems of the 1970s and early 80s, and they make the exact same argument. I never believed that one for some reason…)

Labor unions and strikes were largely responsible for improved working conditions in the 19th and early 20th centuries

In high school, I read Howard Zinn’s A People’s History of the United States and it convinced me of the importance of collective action. The book’s argument went like this:

1. Laborers had to work in really bad conditions.
2. They organized unions and held strikes.
3. Decades later, conditions were still bad but not quite as bad.
4. Therefore, strikes and labor unions were the cause of the improvement in conditions.

The book repeatedly makes this argument through a series of historical anecdotes.⁴ As I recall, it never says the conclusion explicitly, but it’s strongly implied.

At the time, I found the book’s anecdotes convincing. It wasn’t until years later that I realized how weak its case was.

In fact, the book’s argument is even weaker than the Worst Argument In The World. It doesn’t say working conditions were bad, then strikes happened, then many years later conditions were good. It says working conditions were bad, then strikes happened, then conditions were still bad. Which is positive evidence that the strikes didn’t help. Kind of amazing that I read this and came away with the opposite conclusion.

Seed oils cause obesity

There are some arguments about seed oils that don’t rely on this fallacy, but the most popular argument I see goes like this:

1. A century ago, obesity was rare, and also people didn’t eat a lot of seed oils.
2. Today, many more people are obese, and also people eat a lot of seed oils.
3. Therefore, obesity must be caused by seed oils.

I’m almost baffled that anyone finds this convincing, except that I myself was convinced by the Worst Argument In The World in at least two instances as documented above.

Some people get more sophisticated and they draw a line of obesity going up and a line of something-kinda-like-seed-oil consumption (like vegetable oil consumption) going up and they say, look, the lines both go up! That’s not quite as bad as only looking at two data points, but it’s still pretty bad. (You can also draw a line of pirate populations going down and a line of global temperature going up.) It would be better to go a little further and show that the two lines track each other well. That wouldn’t establish causation but at least it establishes correlation.⁵

Martin Luther King greatly improved civil rights for African-Americans

I’m sure there are good arguments for this statement out there somewhere, but I always hear people (implicitly) say things like:

1. In the 1950s, segregation was legal and African-Americans didn’t have equal rights.
2. Then, Martin Luther King spearheaded civil rights protests. Also, a bunch of other stuff happened.
3. By the 1970s, America was a much better place for black people.
4. Therefore, the improvements in civil rights must have been largely caused by MLK.

What makes it the Worst Argument In The World?

Scott Alexander’s Worst Argument In The World is a dirty debate tactic—you say something technically true that subtly invokes a hard-to-spot fallacy. My submission for Worst Argument is almost the opposite—you say something fallacious, and it’s pretty obviously fallacious if you think about it, but we fall for it anyway. The Worst Argument In The World reminds me of the basketball awareness test: Like the moonwalking bear, it somehow sneaks into my brain without getting spotted.

Notes