2025 CSAT — Q2
Passage
Maintaining an ecosystem just to conserve biodiversity will affect its commercial potential as well as the livelihoods dependent on the ecosystem. There is also a conflict between using an ecosystem only for livelihoods, for commercial exploitation, or strictly for conservation. Deforestation caused due to commercial exploitation will lead to indirect harm like floods, siltation problems and microclimatic instability, apart from adversely affecting livelihoods dependent on forests. These conflicts are particularly acute in developing countries where the dependence of people on the ecosystem is significant, and commercial exploitation has the potential to boost national income.
With reference to the above passage, the following assumptions have been made:
I. No country needs to depend on ecosystems to boost national income.
II. Resource-rich countries need to share their resources with those of scant resources so as to prevent the degradation of ecosystems.
Which of the above assumptions is/are valid?
Thinking pathway
Locate. This is a valid-assumption question, so the answer is never a line you can point to — an assumption is an unstated premise the argument leans on. So don’t hunt for a matching sentence; find the argument’s own claims first and test each candidate against them. The passage’s operative claims are: ecosystems are used commercially, and “commercial exploitation has the potential to boost national income.”
Test (the negation test). A statement is a valid assumption iff negating it breaks the passage. Statement I = “No country needs to depend on ecosystems to boost national income.” The passage already asserts the reverse — so I isn’t an unstated premise; it’s a contradicted claim. Statement II (resource-rich countries sharing) isn’t in the passage to negate at all — the argument runs without it. Neither survives as a needed premise, so neither is valid.
Eliminate by anatomy. (a) gets the direction backwards — it treats as an assumption a claim the text states the opposite of (this is the recurring trap: a true-sounding statement the passage contradicts). (b) is a claim the passage never actually makes — a world-plausible policy the passage never raises (the other recurring trap: a reasonable idea the reader supplies). (c) commits both. On a valid-assumption question, “is this true in the world?” is the wrong question; “did the passage need this?” is the right one. Key: (d).
Evidence in the text
“commercial exploitation has the potential to boost national income” contradicts I (countries DO use ecosystems to boost income). For II, the passage contains no mention of resource-rich countries, sharing, or inter-country transfer — the assumption is wholly outside the text.
Worked rationale
An assumption is valid only if the passage’s argument needs it — test each by negation: if negating the statement leaves the passage intact (or the passage already contradicts it), it is not an assumption the author made.
Statement I — “No country needs to depend on ecosystems to boost national income.” The passage says the opposite: “commercial exploitation has the potential to boost national income,” and notes developing countries’ significant dependence. The text contradicts I, so I cannot be an assumption behind it. I is invalid.
Statement II — “Resource-rich countries need to share their resources with those of scant resources…” Nothing in the passage mentions resource-rich vs. resource-scant countries, sharing, or inter-country transfers. The argument runs without it. II is invalid (out of scope).
Both fail. Answer: (d) Neither I nor II.
Why the other options miss
- A gets the direction backwards: treats I as an assumption when the passage explicitly states the reverse (ecosystems do boost national income).
- B a claim the passage never actually makes: imports a plausible policy idea (rich countries sharing) that the passage never raises; mistakes a reasonable-sounding claim for a stated premise.
- C gets the direction backwards: commits both errors, but the dominant, fatal one is endorsing statement I, which the passage explicitly states the reverse of (ecosystems do boost income); statement II is additionally absent from the text. The contradicted claim is what sinks it.
Specialist insight
The valid-assumption question is the one that most punishes the world-knowledge reader. Both distractors here are things one could reasonably believe about the world — but the question is not “is this true?”, it is “did the passage assume this?” The negation test settles it instantly: negate I and the passage strengthens (it already says ecosystems boost income); II isn’t in the passage to negate. The discipline: an assumption must be a premise the argument leans on — read the text, never the world.
Both statements are world-plausible but textually absent or contradicted — a valid-assumption question asks what the passage presumed, not what is true.