Verbal arguments: assumptions, alternative causes and evidence direction
GRE General Test Topic 9 2:14 English narration · English + 中文 subtitles burned in
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This unit separates observations, assumptions and conclusions, chooses evidence that strengthens or weakens the precise argument, and uses an assumption's negation to test whether the argument depends on it.
本单元区分观察、假设和结论，选择能加强或削弱具体论证的证据，并用对假设的否定来检验论证是否依赖于它。
Translate an argument into evidence, conclusion and missing bridge.
把论证拆成证据、结论和缺失的桥梁。
For a causal claim, test alternative explanations, reverse direction and baseline differences.
对因果论断，要检验其他解释、因果倒置和基线差异。
An outcome following a change shows sequence, not the change's effect; a comparison group helps only if it is comparable.
结果发生在变化之后只说明先后，不说明变化的作用；对照组只有在可比时才有帮助。
Strengthening and weakening are directional: a fact can make the conclusion more or less plausible without proving it.
加强与削弱是有方向的：一个事实可以使结论更可信或更不可信，而不证明它。
For a necessary assumption, negate the candidate and ask whether the argument loses its support.
对必要假设，否定候选项，看论证是否失去支持。
Keep scope precise: average improvement differs from every participant improving.
范围要准确：平均提高不等于每个参与者都提高。
Students who chose the optional workshop scored higher, so the workshop caused the higher scores.
选择参加自愿复习班的学生分数更高，所以复习班导致了高分。
The bridge is that self-selection did not explain the difference.
桥梁是：自我选择并不能解释这一差异。
If attendees already scored higher before, the claim weakens; if comparable students were randomly allocated, it strengthens.
若参加者之前就分数更高，论断被削弱；若可比的学生是随机分配的，论断被加强。
A fact can be relevant to the topic without affecting the inference.
一个事实可能与话题相关，却不影响推论。
Identify the mechanism by which it changes support.
要指出它改变支持程度的机制。
A pre-existing completion difference supplies a self-selection explanation, so A weakens most.
原先就存在的完成时间差异提供了自我选择的解释，所以 A 削弱力度最大。
B and C have no stated link to the outcome, and D measures satisfaction rather than effect.
B 和 C 与结果没有明确联系，D 衡量的是满意度而不是效果。
A does not prove the session had no effect.
A 并不能证明这个课程毫无作用。
A necessary bridge is that no applicant is unable to understand the guide.
一个必要的桥梁是：没有申请人看不懂这份指南。
Negate it: at least one cannot, and the universal claim loses its support.
否定它：至少有一人看不懂，普遍性论断就失去支持。
Being able to read is weaker than actually reading.
“能读”弱于“确实读了”。
Fewer errors among comparable guide users would strengthen the claim without proving all.
可比的使用者中错误更少，会加强论断，但不能证明“所有”。
Check yourself.
自我检测。
An outcome after a change shows sequence.
变化之后出现结果只说明先后。
A prior score gap weakens the workshop claim.
原有的分数差距削弱复习班的论断。
The planning-session answer is A.
计划课程题选 A。
Test a necessary assumption by negating it.
用否定来检验必要假设。
And an average rise does not mean everyone rose.
平均提高不等于每个人都提高。