Straw men, false choices, weak causation, and moving-goalpost problems

What to take away

• Diagnose the broken inference, not merely the label.
• A straw man replaces a serious position with an easier one.
• A false choice hides live alternatives or combinations.
• Sequence and correlation alone do not establish cause.
• Moving goalposts change the standard after evidence meets the original demand.

Fallacy names are useful only when they help repair reasoning. Calling a paragraph "a straw man" without identifying the distortion leaves the writer little to revise. This guide pairs each common problem with a test and a concrete fix.

Problem 1: The straw man

A straw man misstates an opposing position so it becomes easier to reject.

Draft: "Supporters of slower downtown traffic want to ban cars."

Suppose the documented proposal calls for a 20 mph limit on three streets. The draft has changed a speed rule into a vehicle ban.

Diagnostic questions:

• Can the opposing side recognize its claim?
• Have conditions or exceptions been removed?
• Is the response aimed at words the source never used?
• Has a fringe statement replaced the main documented case?

Repair: quote or paraphrase the proposal at its strongest supported scope, explain why a reasonable person could accept it, and answer that version.

Purdue OWL's guide to common logical fallacies defines the straw man as an oversimplified opposing view and the either-or fallacy as reducing a complex issue to two choices. Its practical warning is that a distorted opponent does not establish the writer's own conclusion.

Problem 2: The false choice

A false choice presents two options as exhaustive when other positions, hybrids, degrees, or sequences remain possible.

Draft: "Either the museum digitizes its entire archive now or it does not care about access."

Missing possibilities include phased digitization, priority collections, partnerships, on-demand scanning, improved catalogs, and better physical access.

Repair with an option matrix:

Option	Cost	Access gain	Rights burden	Time
Full immediate program	High	Broad	High	Short
Phased priority program	Medium	Targeted	Medium	Medium
Catalog-first program	Low	Indirect	Low	Short
No change	Low now	None	None	None

Then defend a choice against the real alternatives.

Problem 3: Weak causation

Draft: "Complaints fell after the new form launched, so the form solved the problem."

The timing is compatible with that explanation, but it does not isolate it. Reporting behavior, staffing, seasonality, eligibility, and counting rules may have changed.

Use a causal repair sequence:

1. Verify the outcome measure before and after.
2. Establish the order of events.
3. Identify plausible rival causes.
4. Look for a comparison or interrupted trend.
5. Test a mechanism.
6. Reduce the claim if those tests are unavailable.

Safer revision: "Recorded complaints declined after the form launched, but the available records do not separate the form's effect from staffing and reporting changes."

Problem 4: Moving the goalposts

This problem occurs when the required proof changes after the other side meets the stated standard.

Sequence:

• Initial demand: show that the pilot reduced average wait time.
• Evidence: audited records show a 12 percent reduction.
• New demand: prove that every user waited less.
• After individual cases are supplied: prove the improvement will last for ten years.

Standards can be revised for good reasons, such as discovering that the first measure was inadequate. The error lies in changing them opportunistically while pretending the original standard was never met.

Repair: define the burden before evaluating evidence. If it changes, state why, apply the new rule consistently, and acknowledge what the earlier evidence established.

Problem 5: Slippery chains without support

A policy may have downstream effects, but a chain needs support at each step.

Draft: "Allowing one late assignment will erase all deadlines, collapse course standards, and make grades meaningless."

The MIT OpenCourseWare handout on logical fallacies describes a slippery-slope argument as claiming that one action must lead to a sequence of consequences without sufficient justification. To repair the passage, support the probability and mechanism of each transition or stop where the evidence stops.

Problem 6: Conclusion drift

An essay may begin with one claim and end with a larger one.

• Evidence: two classes preferred shorter lectures.
• Supported result: those surveyed students reported that preference.
• Drifted conclusion: universities should replace lectures everywhere.

Draw a boundary around population, measure, setting, and time. Copy those boundaries into the conclusion. A preference is not necessarily a learning outcome, and two classes are not all universities.

A repair table

Problem	Broken move	Repair
Straw man	Distorts an opponent	Restate strongest documented version
False choice	Hides live options	Map alternatives and combinations
Weak causation	Treats sequence as cause	Test rivals or qualify
Moving goalposts	Changes proof standard	Predefine and apply criteria
Unsupported chain	Assumes every later step	Support each transition
Conclusion drift	Expands beyond evidence	Restore scope boundaries

Common questions

Does using a fallacy label prove an argument is wrong?

No. Show the specific premise, inference, or representation that fails.

Can a two-option choice ever be fair?

Yes. Demonstrate that the options are exhaustive under the stated conditions.

Is correlation useless?

No. It can describe a relationship and motivate further inquiry. It simply does not establish cause by itself.

Is changing an evidence standard always unfair?

No. New information can expose a bad standard. Explain the revision and apply it consistently.