In the question given below, statement and two assumptions (I) and (II) are given. Choose the correct option from the following : Statement : In order to replenish the nutrients in the soil, it is important to grow different types of crops in every alternate season. Assumptions : (I) A crop can never be grown for the second time in the same field. (II) If a different crop is grown in the successive season, no additional nutrients such as fertilizers are required to be added to the soil at all.

Correct — option (4), Neither assumption (I) nor assumption (II) is implicit.

An assumption is implicit only when the statement cannot make sense without it. The check: reverse the assumption and see whether the statement still stands.

Assumption (I) says a crop can never be grown a second time in the same field. Reverse it: a crop can return to the same field. The statement still stands, because asking for different crops in every alternate season leaves room for a crop to come back after a gap.

Assumption (II) says a different crop in the next season means no fertilisers are needed at all. Reverse it: some fertiliser may still be needed. The statement still stands, because it calls crop change important for replenishing nutrients, not sufficient on its own.

The statement needs neither assumption, so the answer is Neither assumption (I) nor assumption (II) is implicit.

The idea to remember: an assumption must be something the statement needs, not a stronger claim built on top of it.

Why the others are wrong

• (1)
  Only assumption (I) is implicit. — Option (1) accepts assumption (I), that a crop can never be grown twice in the same field.

  The statement only asks that crops change every alternate season. That plan does not forbid a crop from returning later. Reverse (I) — a crop can return — and the statement loses nothing, so (I) is not something it depends on.

• (2)
  Only assumption (II) is implicit. — Option (2) accepts assumption (II), that a change of crop removes the need for fertilisers at all.

  The statement says growing different crops is important for replenishing nutrients. Important is not the same as enough. Reverse (II) — some fertiliser may still be needed — and the statement still makes sense, so (II) goes beyond it.

• (3)
  Both assumptions (I) and (II) are implicit. — Option (3) needs both assumptions to pass the test, and each fails on its own.

  (I) adds "never", which the statement does not need; (II) adds "at all", which the statement does not need either. One failed assumption is enough to rule this option out; here both fail.

An assumption is an unstated premise: something a speaker takes for granted without saying it. In reasoning, it counts as implicit only if the statement depends on it.

The negation test checks this. Reverse the assumption and read the statement again. If the statement now makes no sense, the assumption was implicit. If the statement survives, it was not.

Words such as never, always, only and at all make an assumption stronger. A stronger version is implicit only when the statement itself needs that strength. Recommending a practice does not, by itself, commit a speaker to "never" or "at all".

Key facts

• An implicit assumption is an unstated premise the statement depends on; if the statement makes sense without it, it is not implicit.
• Negation test: reverse the assumption; if the statement then loses its sense, the assumption was implicit.
• The statement calls growing different crops important for replenishing soil nutrients; it does not call it sufficient.
• Changing crops every alternate season does not stop a crop from being grown again in the same field later.
• Leguminous crops host Rhizobium bacteria in root nodules, which fix atmospheric nitrogen.

Common traps

• "Important" is not "sufficient". The statement values a change of crops; assumption (II) turns that into a claim that nothing else is needed.
• Agreeing with an assumption is not the test. A sentence can be true about farming and still not be something this statement depends on.
• Assumption (I) says a crop can never return to a field. The statement only asks that crops be varied, which does not rule a return out.

UnlockIAS will link similar questions from RAS Pre 2023, 2018 and 2016 here once those papers are published on this site.

• practice — not a real PYQ

  Statement: Farmers in the district should shift to drip irrigation to save groundwater. Assumptions: (I) Drip irrigation uses less water than the methods the farmers use now. (II) Groundwater in the district needs to be conserved.

  • (a)Only assumption (I) is implicit.
  • (b)Only assumption (II) is implicit.
  • (c)Both assumptions (I) and (II) are implicit.
  • (d)Neither assumption (I) nor assumption (II) is implicit.
  Answer(3) — Reverse (I): if drip irrigation did not use less water, shifting to it could not save groundwater, so the advice collapses. Reverse (II): if groundwater did not need saving, the stated purpose makes no sense. Both are needed. Options (1) and (2) each drop one needed assumption; option (4) drops both.
• practice — not a real PYQ

  Statement: The school has started a morning yoga session to improve students' concentration. Assumptions: (I) Yoga can help improve concentration. (II) Students who do not do yoga can never concentrate.

  • (a)Only assumption (I) is implicit.
  • (b)Only assumption (II) is implicit.
  • (c)Both assumptions (I) and (II) are implicit.
  • (d)Neither assumption (I) nor assumption (II) is implicit.
  Answer(1) — Reverse (I): if yoga could not help concentration, starting a session for that purpose makes no sense, so (I) is implicit. Reverse (II): some students concentrate without yoga — the school's step still makes sense, so (II) is not implicit. Option (2) picks the wrong one, option (3) wrongly adds (II), and option (4) wrongly drops (I).