What logical fallacy is this?

[Dominus]

I see people use this line of flawed logic often enough that I'm sure there is a name for this logical fallacy. I'll describe a few scenarios so you understand what I'm trying to describe.


Engineering group evaluates an old bridge and tells the client the bridge needs major repairs or it might fail in the next year. The client agrees to fund the repairs. Repairs are done. A year later, the client says "it's been a year and the bridge hasn't failed, we wasted money on repairing it!" The client just committed this fallacy.

Another scenario. Doctor tells patient that he needs to perform a standard procedure to prevent a possible heart attack in the near future due to clogged arteries. The procedure is done. A couple years later, the patient proclaims "hey, it's been 2 years and I haven't had a heart attack. The procedure was unnecessary!" The patient just committed this fallacy.

The 2nd one was based on a real person and true event, actually.

Here is another scenario. A major city is flooded from a failed levy system during a cat 4 hurricane event. The state spends a lot of money on a new levy system. The next cat 4 hurricane arrived and at the end no flooding happened. The press attacks the state for having wasted all that money to build a modern levy system. Hey look, I ain't see no flooding, so the new levy was unnecessary! Again, this was based on a real event.

I see people committ this fallacy all the time. There has got to be a formal name for it, right?

 

[mikey3000]

It's called success. The bridge repairs were a success. The heart surgery was a success, and so was the new levy. Aren't some people amazing?

 

[luckynumbah7]

Sounds like Affirming the consequent.

 

[Dominus]

^ No. You cited a formal fallacy. What I'm thinking of is an informal one.

Edit.

Here is another example.

Bob for the last 10 years have been getting the flu shot every year. Bob never got the flu. One day Bob complains that he's never had the flu for the last 10 years, so the flu shots have been useless. He ignores the fact that the flu shots have been what's keeping him from getting a bad flu.

I see people use this flawed line of logic all the time. A preventative measure is put into place. Disaster is prevented. Then people complain that since there was no disaster the preventative measure was unnecessary, ignoring that the measure prevented the disaster from happening.

 

[luckynumbah7]

^ No. You cited a formal fallacy. What I'm thinking of is an informal one.

So take it out for dinner & a couple drinks....?

Bah humbug. Gimmie ten minutes, if you'd be so kind.

(However, you did, in your original statement, request a formal fallacy)

 

[medic1]

It is the logical fallacy known as being human.

 

[KaraBulut]

Here is another scenario. A major city is flooded from a failed levy system during a cat 4 hurricane event. The state spends a lot of money on a new levy system. The next cat 4 hurricane arrived and at the end no flooding happened. The press attacks the state for having wasted all that money to build a modern levy system. Hey look, I ain't see no flooding, so the new levy was unnecessary! Again, this was based on a real event.

Tax or embankment?

levee [lev-ee] - an embankment designed to prevent the flooding of a river.

levy [lev-ee] - an imposing or collecting, as of a tax, by authority or force.

 

[Dominus]

So take it out for dinner & a couple drinks....?

Bah humbug. Gimmie ten minutes, if you'd be so kind.

(However, you did, in your original statement, request a formal fallacy)

Typo

 

[Dominus]

Tax or embankment?

levee [lev-ee] - an embankment designed to prevent the flooding of a river.

levy [lev-ee] - an imposing or collecting, as of a tax, by authority or force.

Embankment.

 

[Dominus]

It is the logical fallacy known as being human.

Well, all logical fallacies can be seen as being human. But there are still names for them. For example, a very common one that many people use regularly is tu quoque. I'm probably guilty of having used this one before. Another common one is strawman.

What I described in the OP I've seen often enough that (to me) there has to be a name for it.

You work out often and eat healthy. Then one day you say "I'm not fat, so exercising and eating healthy have been pointless" ignoring the fact that working out often and eating healthy all these years have prevented you from getting fat.

Here's another example. Your mom tells you it is cold outside so bundle up. You wear 3 layers of clothing plus a heavy coat. Once you're outside, you proclaim "hey I don't feel that cold, mom was lying that it was cold outside!" ignoring the fact that all those layers prevented you from feeling too cold.

While driving home one night, your friend insists that you don't go above 10 above the speed limit. You do so and never got pulled over. When you got home, you proclaim "hey, I never got pulled over, so I could have driven 50 over the speed limit!" ignoring the fact that staying below 10mph above the speed limit on the highway got you home without getting pulled over.

I could go on and on with the examples.

Dare I bring up the y2k bug? Most people nowadays believe that it was nothing and all the preventative measures put in place were unnecessary, ignoring the fact that all the preventative measures were what kept anything from happening.

 

[medic1]

^I do see and understand your point of view.

However, being human you find these fallacies all the time.

 

[Alnitak]

Slothful induction.

 

[Alnitak]

Note that this is also outcome bias.

 

[Rickrock]

Fortunately, I don't see this fallacy/logic used very often. I didn't know that people named flawed logic or fallacies. It seems that I had a course on logic in college, but I don't remember much from it now.

 

[Dominus]

Fortunately, I don't see this fallacy/logic used very often. I didn't know that people named flawed logic or fallacies. It seems that I had a course on logic in college, but I don't remember much from it now.

Trust me, you see this often enough. You just don't recognize it most of the time. The examples I gave are made to be bleedingly obvious. In real life, they are a lot less obvious.

Here is a real life example that isn't so obvious.

Have you ever talked to an anti-vaxxer? I personally know several. One of the most prevalent (false) arguments they make is vaccines are unnecessary because look around us there aren't any outbreak of these diseases. Polio is gone. Smallpox is gone. Most diseases that used to kill millions are either gone or on their way to being gone. So, according to their (false) logic, we don't see these diseases anymore so therefore vaccines have always been unnecessary.

Think about that for a moment. We know for a fact that the reason that most of these diseases have been eradicated or are on their way to being eradicated is because we have been vaccinating people for decades. That's the point of vaccination. To prevent outbreaks of these diseases. But to the anti-vaxxers, in their warped minds they think that the lack of these outbreaks is somehow proof that vaccines are pointless and have always been pointless.

If I think hard enough, I can probably think of more subtle examples. But the point is I've seen people using this fallacy quite often over the years. I'm just surprised that there isn't a name for it (yet).

 

[NotHardUp1]

It is little more than selective memory. There hasn't been a logic applied per se.

The customer or client has merely regurgitated part of the conversation from two years prior and divorced it from the if/then statement. "You SAID the bridge would fail!" "No, we said it would fail IF we did not do the work. We did the work."

The anti-vaxxers example is fallacious. They don't argue that vaccination is unnecessary. They argue that they believe it causes autism and they prefer to take their chances in a relatively clean population, essentially riding on the backs of the vast majority who do comply with sane practice. Any actual student of epidemiology knows the diseases still exist and that their abatement is the direct result of great efforts. Only willful ignorance could allow anyone to claim they have "disappeared on their own."

You are really dealing with two different problems. One is a forgetful "debater," and the latter is one willfully ignoring the facts, much like those who support the border wall. Willful ignorance vs. selective memory.

 

[NotHardUp1]

Oh, and everything Matt said.

 

[NotHardUp1]

The power of logic:

 

[LeicsDom]

I see people use this flawed line of logic all the time. A preventative measure is put into place. Disaster is prevented. Then people complain that since there was no disaster the preventative measure was unnecessary, ignoring that the measure prevented the disaster from happening.

It's called idiocy
In the same way that if a person is ill and a relative prays for them. They recover therefore it is down to the prayer. Never mind that they got better anyway

 

[rareboy]

I see people use this line of flawed logic often enough that I'm sure there is a name for this logical fallacy. I'll describe a few scenarios so you understand what I'm trying to describe.


Engineering group evaluates an old bridge and tells the client the bridge needs major repairs or it might fail in the next year. The client agrees to fund the repairs. Repairs are done. A year later, the client says "it's been a year and the bridge hasn't failed, we wasted money on repairing it!" The client just committed this fallacy.

Another scenario. Doctor tells patient that he needs to perform a standard procedure to prevent a possible heart attack in the near future due to clogged arteries. The procedure is done. A couple years later, the patient proclaims "hey, it's been 2 years and I haven't had a heart attack. The procedure was unnecessary!" The patient just committed this fallacy.

The 2nd one was based on a real person and true event, actually.

Here is another scenario. A major city is flooded from a failed levy system during a cat 4 hurricane event. The state spends a lot of money on a new levy system. The next cat 4 hurricane arrived and at the end no flooding happened. The press attacks the state for having wasted all that money to build a modern levy system. Hey look, I ain't see no flooding, so the new levy was unnecessary! Again, this was based on a real event.

I see people committ this fallacy all the time. There has got to be a formal name for it, right?

Being an fucking idiot. That is the name for it.