What is the name of this informal fallacy - not accounting for second order consequences?

I think by your standard, many of the things commonly described as informal fallacies would not be such.

Also, I would not consider the informal fallacy to have arisen where there is disagreement about second order consequences. The fallacy arises where they are ignored or forgotten.

In other words to my mind the fallacy has not been committed if in the “birds on a wire“ example, those participating in the discussion have considered but disagree about what the birds will do consequent upon the first shot. The fallacy is committed where someone simply does not consider the fact that the situation will change upon the first shot.

As a fallacy I think this is a derivative of the false dilemma. Just like the false dilemma the range of possibilities is ignored in favor of just one. In this case there is a dilemma but it is not recognized.

So instead of a false dilemma because the alternatives are not considered, this is a false lack of a dilemma because the alternatives are not considered.

Sure, some might. I think it’s been well established that “fallacy” gets used too often. People like the idea of being able to play the “Fallacy of the Dutchman’s crumpet” or whatever card (don’t Google it, I just made it up), and immediately win. But unfortunately, things usually aren’t that simple.

If you have a specific example of an informal fallacy that actually refers to something subjective, I’d definitely be interested to discuss it, here or in another thread.

Sure, but as I said in a previous post, exactly how you break down a situation, and what is secondary, tertiary or whatever, is arbitrary.
For example, with the “reduce to one lane” example from the OP. We could say a first order effect is traffic jams on that road, and second order is more drivers using other routes. Or we could say first order is drivers being insentivized to switch routes and secondary is traffic jams on surrounding routes.
Or whatever.
If it’s a fallacy to ignore second order effects and nothing else, then we get different answers as to what proposals technically meet this fallacy.

What does this mean? I think all the “cognitive fallacies” are subjective. Do you dislike the term “cognitive fallacy”, or do define them as “not subjective”?

Firstly, what even are cognitive fallacies? I am familiar with cognitive biases and logical fallacies, but not their redheaded lovechild.

But secondly, no, personally I would not like for the word “fallacy” to be watered down to just mean any error in judgement or bias.
A fallacy is an error in the logic of the argument itself; with a formal fallacy being when a conclusion is drawn that doesn’t follow from the premises and an informal fallacy is where the premise(s) are incorrect or irrelevant.
None of that is the case here, so I think it best to use another noun for the issue being outlined here (there are plenty in the English language), rather than misuse the word “fallacy”.

I think this is a fallacy.

What you are talking about is a logical fallacy, and sometimes (based on context) we use just the word fallacy as shorthand for this. But the word fallacy certainly has a broader meaning that encompasses even straightforward factually incorrect beliefs, such as my first sentence in this post, or:

It is a fallacy that Benjamin Franklin was president.

If the word can encompass this meaning, it seems quite odd to suggest that it must exclude flawed reasoning such as that described by the OP that is not a strict logical fallacy.

That’s all very confused:

  • The observer effect is the idea that observing something changes it. It isn’t always true; after all, how does observing the Eiffel Tower affect it?
  • The only time it’s impossible to know everything about a system is when it’s quantum. That is the Heisenberg Uncertainty Principle, but it doesn’t apply to anything we’re talking about.

I disagree.

A huge number of scientific and technical terms have a much broader usage in colloquial English, from quantum leap to exponential, from survival of the fittest to the butterfly effect.

But when someone asks in a discussion forum “What kind of quantum leap is this?” we’re inclined to evaluate it as referring to the strict term, otherwise the question is largely pointless. If we’re just talking colloquialisms then use whatever word you like; call it a fallacy today, call it a fucknuts tomorrow; whatever you think will best convey your meaning to your current audience.

Gilks sighed. “You’re a clever man, Cjelli, I grant you that,” he said, “but you make the same mistake a lot of clever people do of thinking everyone else is stupid.”

-Douglas Adams

Not quite.

The whole idea behind chaos theory is that in both theory and in practice it’s impossible to know everything about even a moderately complicated macro-scale multi-component system to a fine enough tolerance that you can accurately predict its future trajectory.

Nitpick on top of a nitpick :slight_smile:

You can predict the future trajectory of many chaotic systems. The practical limit is on how far ahead you can predict, and how accurately, before the system completely diverges from the anticipated values. The practical limit indeed exists for the reason you say though.

I am confident no-one will be able to nitpick this…

Congrats on a fine nitpick. One that avoids crossing the line into a nutpick. Bravo!

Come on SDMB, a hyphen in “no one” must be somebody’s pet peeve?

Are you denying that the word “fallacy” has any valid or useful colloquial meaning that differs from “formal logical fallacy”? I hope that’s not your position. If it is, I guess we will have to part ways on the question of whether you are the boss of language.

As for how someone might phrase something in a hypothetical discussion forum to clarify that they understood that they were not referring to a formal logical fallacy, perhaps a hypothetical OP could avoid any ambiguity by using the phrase “informal fallacy” rather than just “fallacy” in their hypothetical thread title?

Yes. The solar system is chaotic, but over time spans of millenia, the orbits of the planets are quite predictable (asteroids not so much, and tiny moonless even less so, I suspect)

I think you are confused here.
“Fallacy” in the colloquial sense has a very broad meaning and could be just about any error of judgement or alternatively a common misconception or myth.

Meanwhile, an “informal logical fallacy” has a much more precise meaning; it’s a logically flawed argument because of an invalid or irrelevant premise.

The OP is very clearly asking about (in)formal logical fallacies by asking “What fallacy is this?”
Because it wouldn’t make sense to talk about discrete, specific fallacies when using the word in the broad colloquial sense.

It would be like a thread asking “How might aliens get to Earth?”. It would be pretty silly for me to reply “Well alien in a colloquial sense can just mean human foreigner (as in “illegal alien”), therefore they’re already here”. Right?

Why isn’t “we can adopt a simplified model of cause and effect that ignores second order effects in order to approximate the outcome” a potentially invalid premise?

I guess my point would be that there must be a name for the somewhat analogous principle in psychology (and hence, other fields). You can administer a test - “which colour would you pick?” or “who would you award the $10 to?” or “which one of these is more appealing?” - but since the subjects must know this is a psychology experiment, that may affect how they answer. The fact they know their motives may be closely examined affects their response. The observer changes the system.

Close to what the OP is asking - we want to determine a reason for, let’s say, a human making a particular choice. But by constructing that choice in a setting where there are observers - not a natural setting - that affects the result. The existence of observation is an added factor.

I think that this sort of thing falls under the (admittedly wider) umbrella of ignoratio elenchi: you fail to take into account further information that refutes the conclusion you would like to draw. So, if you would like to draw the conclusion ‘there will be a traffic jam’, you must ignore the refuting premise ‘if the traffic capacity of the street is reduced, people will find another way’.

But this doesn’t quite capture the ‘second order’-nature of the ignored information—that is, something that is only true because of a certain proposed intervention.

It’s also a type of enthymeme, in that the implied argument isn’t given fully, but has an unstated premise that all else remains equal. But that’s of course an even wider term.

One could also think of it as a case of hasty generalization, because it implicitly assumes that the conditions valid now will continue to be valid—so one illicitly takes a small sample of cases (with conditions comparable to the present ones) to be representative of all possible cases.

I hereby dub it the “dumb pugilists fallacy”. Like if a boxer gets in the ring and is miffed that the other guy is hitting back.