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Post Hoc Fallacy: The Art of Phony Persuasion

I've spent half a century writing for radio and print (mostly print). I hope to still be tapping the keys as I take my last breath.

In simple terms, the post hoc fallacy states that if A happens before B, then A is the cause of B. Let’s take a ridiculous example:

Suppose you have a boiled egg for breakfast. Later, the letter carrier delivers a cheque. The post hoc fallacy says eating boiled eggs brings cheques. Most of us can see the absurdity of that, but clever folks have learned to disguise this line of argument to make it more plausible.

Let’s have a little Latin, which is used to describe the whole concept; it’s not long and there is a translation. The concept is called “Post hoc ergo propter hoc.” It means literally: “After this and therefore because of this.”

The crucial part of that statement is “therefore.”

The Celebrity Endorsement

Seven-time Formula 1 world champion Lewis Hamilton is a pitchman for the Bank of Santander. There is no denying that Hamilton is an exceedingly accomplished racing driver, but if he’s an expert in international finance, it’s a skill that has so far gone undisclosed. What the bank is saying is “If Lewis Hamilton is (young, cool, highly talented), then so is Santander.”

But it’s a post hoc fallacy.

Here’s another one:

The People for the Ethical Treatment of Animals used actor Alicia Silverstone to sell the idea of vegetarianism. There is the sleek and undeniably beautiful Silverstone without a stitch of clothing on. So, here’s the pitch―“Stop eating meat and you’ll look like me.” It works for men too―“Stop eating meat and you’ll be with drop-dead gorgeous women like me.”

There is no connection whatsoever between vegetarianism and the allure of Alicia Silverstone, whether clothed or unclothed. It’s a post hoc fallacy.

During the 2016 presidential election in the United States, Hillary Clinton picked up celebrity endorsements by the bushel basket. Beyoncé, Jay-Z, George Clooney, Meryl Streep, Magic Johnson, and just about everybody else from the A-list of stars supported Hillary. However, the political acumen and government experience of the whole panoply of celebs could not fill a thimble. We all know how well their endorsements worked out for the candidate.

Political Fallacies

Of course, we’d never expect a politician to use a phony argument. Hah!

These folks can straight-out lie without blushing, so the distorting of reality is meat and drink to them.

In November 2015, a gunman opened fire at a Planned Parenthood (PP) clinic in Colorado Springs, killing three people. PP had been the subject of criticism from anti-abortion activists.

Immediately after the shooting, Senator Bernie Sanders jumped into a post hoc fallacy. In a statement he said:

“While we still do not know the shooter’s motive, what is clear is that Planned Parenthood has been the subject of vicious and unsubstantiated statements attacking an organization that provides critical health care for millions of Americans. I...hope people realize that bitter rhetoric can have unintended consequences.”

Sanders admitted he didn’t know why the gunman did what he did, but that didn’t stop him from making a connection that wasn’t necessarily there.

But step aside Bernie—you’re in the presence of the king of Post hoc ergo propter hoc. During his presidential campaign, Donald Trump broke the world record for post hoc fallacies. (That’s hyperbole, because there is no such record, but if there was, Trump would certainly hold it). Examples could, and probably will, fill a book. Here are a couple of his false equivalencies:

  • During the campaign he said “. . . almost 4,000 people have been killed in the Chicago area since he (President Obama) took office.” The post hoc fallacy here is that the election of Obama was the cause of all the violent deaths in Chicago. Nonsense, because the Windy City was already subject to massive street violence before the 2008 election. However, Trump achieved his goal; he planted a connection between violent crime and Barack Obama into minds that are not especially inquiring.
  • On another occasion, Trump claimed his get-tough-on-crime policies “will begin with safety at home, which means safe neighbourhoods, secure borders, and protection from terrorism.” The lapse of logic is that secure borders and safe neighbourhoods will do nothing to stop domestic violence within the home.

Religious Falsehoods

The Roman Catholic Church used the post hoc fallacy for centuries through its program of indulgences. The notion of the indulgence is that upon death a person will get a lesser punishment for his or her sins in exchange for certain services.

The action might be specific good works or saying particular prayers. There was a seamier side to this deal that involved selling indulgences. (It’s what got Martin Luther all hot under the collar, but that’s another story). Rich people paid the church to ensure a smooth passage to heaven. It was a great scheme because nobody could ever return and demand a refund.

Buying a place in heaven.

Buying a place in heaven.

In New Zealand, atheists have latched onto the post hoc fallacy. The No God organization in that country ran a billboard campaign. The ad used the argument that more than one million New Zealanders did not believe in God, therefore there isn’t a god. That’s a rubbish conclusion. The existence or non-existence of God is not provable by a popularity contest.

The post hoc fallacy conceals itself cleverly; sharp eyes and a skeptical intellect are needed to ferret it out.

Bonus Factoids

  • Sometimes celebrity endorsements can backfire. Just ask the folks who hired Bill Cosby (Jello), Jared Fogle (Subway), and Tiger Woods (a ton of things).
  • In his 1956 book, Guides to Straight Thinking, Stuart Chase wrote that “Malaria was for centuries a baffling plague. It was observed that persons who went out at night often developed the malady. So, on the best post hoc reasoning, night air was assumed to be the cause of malaria, and elaborate precautions were taken to shut it out of sleeping quarters.” In reality, the malaria-carrying anopheles mosquito is active after dark.


This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

© 2016 Rupert Taylor