2022 CSAT — Q33

Locate. This is a valid-assumptions question: find each statement’s source line and test it for fit. The passage: natural selection can’t anticipate the future, so organisms “can never be fully prepared,” and “an outcome of this is the extinction of those species which cannot overcome environmental adversity”; “more than 90% of species that have ever lived on the earth are now extinct”; Darwinian laws “are acceptable just like the laws proposed by Copernicus, Galileo, Newton and Einstein—sets of natural laws that explain natural phenomena.”

Test (negation test + boundary check). Statement 1 — “only species able to overcome catastrophes will survive and perpetuate.” The passage’s stated mechanism is that those which cannot overcome go extinct; the survival side — that the survivors are exactly the overcomers — is the assumption that mechanism rests on. Negate it (some non-overcomers also survive) and the extinction logic breaks. VALID. Statement 2 — “more than 90%… ARE IN THE DANGER of getting extinct.” The passage’s number is about species already extinct (a completed historical fact), not species currently at risk. This swaps a past completion for a present danger — a tense-and-qualifier distortion. INVALID. Statement 3 — “Darwin’s theory explains ALL the natural phenomena.” The passage likens Darwinian laws to other natural laws that “explain natural phenomena” — it never says they explain all phenomena. “All” is an absolutist overreach, too strong for what the passage says. INVALID.

Eliminate by anatomy. (b) seats St.2 — a change in the passage’s level of certainty: “90% already extinct” re-read as “90% in danger of extinction.” (c)/(d) seat St.3 — too strong for what the passage says: a comparison to natural laws inflated to “explains all phenomena.” (d) also re-imports St.2. The transferable rule: watch the tense/quantifier — an already-completed fact is not a present danger, and “explain natural phenomena” is not “explain ALL natural phenomena.” Only St.1 survives. Key: (a).

Statement 1 — “the set of existing organisms can never be fully prepared for environmental catastrophes… An outcome of this is the extinction of those species which cannot overcome environmental adversity”: the survival mechanism the passage states (non-overcomers go extinct) presumes that survivors are precisely those able to overcome — negate St.1 and the extinction mechanism collapses → VALID. Statement 2 — the passage says “more than 90% of species that have ever lived on the earth ARE NOW EXTINCT” (a completed past fact), NOT that 90% “are in the danger of getting extinct” (a present risk) → QUALIFIER/tense distortion (already-extinct → at-future-risk) → INVALID. Statement 3 — the passage says Darwinian laws “explain natural phenomena,” like Copernicus’s/Newton’s; “explains ALL the natural phenomena” inflates this to an absolute the text never claims → QUALIFIER (over-strong “all”) fails → INVALID. → (a).

The passage explains extinction as the fate of species that cannot withstand environmental/biological assaults, cites that >90% of species that ever lived are now extinct, and ranks Darwinian laws alongside Copernican/Newtonian natural laws.

Statement 1 is the assumption the extinction mechanism needs: if survival tracks the ability to overcome adversity, then only overcomers persist. Negating it breaks the passage’s logic. Valid.

Statement 2 misreads the 90% figure: the passage says 90% are already extinct, not that 90% are in danger of extinction. A past completion is recast as a present threat. Invalid.

Statement 3 inflates “natural laws that explain natural phenomena” into “explains all natural phenomena.” The absolutist “all” is never claimed. Invalid.

Answer: (a) 1 only.

This three-statement item is a clinic in two boundary crossings. St.2 fails on a tense/quantifier slip — “are now extinct” (done) vs “are in the danger of getting extinct” (pending); the words look close but the truth-conditions are opposite. St.3 fails on a single inflated quantifier — “explain natural phenomena” is a modest comparison to other sciences, not “explain all phenomena.” Only St.1, which the extinction mechanism genuinely presumes, survives. The reading reflex: when a statement quietly shifts a tense or strengthens a quantifier, it has left the passage. (a).