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Question

Read the given statements and conclusions carefully. Assuming that the information given in the statements is true, even if it appears to be at variance with commonly known facts, decide which of the given conclusions logically follow(s) from the statements.

Statements:

All boxes are gifts. 

All gifts are cards. 

Conclusions :

I. Some boxes are cards.

II. All cards are boxes. 

The correct answer is

Only conclusion I follows

Analyzing Statements and Conclusions in Logical Reasoning

This problem requires us to analyze the given statements and determine which of the provided conclusions logically follow based on the information given in the statements, even if it contradicts known facts.

Understanding the Statements

We are given two statements:

  • Statement 1: All boxes are gifts.
  • Statement 2: All gifts are cards.

These statements establish relationships between three categories: Boxes, Gifts, and Cards.

Evaluating the Conclusions

We need to evaluate two conclusions:

  • Conclusion I: Some boxes are cards.
  • Conclusion II: All cards are boxes.

Evaluation of Conclusion I: Some boxes are cards.

Let's trace the relationship from Boxes to Cards using the given statements:

  • Statement 1 says: Every single item that is a 'box' is also a 'gift'. We can represent this as Boxes <span>&sube;</span> Gifts (Boxes are a subset of Gifts).
  • Statement 2 says: Every single item that is a 'gift' is also a 'card'. We can represent this as Gifts <span>&sube;</span> Cards (Gifts are a subset of Cards).

If all boxes are gifts, and all gifts are cards, then it logically follows that all boxes must also be cards. Think of it like nested categories: If category A is inside category B, and category B is inside category C, then category A must be inside category C.

So, from "All boxes are gifts" and "All gifts are cards", we can deduce "All boxes are cards".

If it is true that "All boxes are cards", then it must also be true that "Some boxes are cards". This is because if every member of a group (boxes) belongs to another group (cards), then certainly at least one member (and in fact, all members) of the first group belongs to the second group. The statement "Some" in logic means "at least one".

Therefore, Conclusion I ("Some boxes are cards") logically follows from the given statements.

Evaluation of Conclusion II: All cards are boxes.

Let's consider the relationship from Cards to Boxes. The statements tell us about the relationship from Boxes to Gifts and Gifts to Cards, but not directly the other way around in a universal sense.

  • Statement 1: All boxes are gifts. (This does NOT mean all gifts are boxes).
  • Statement 2: All gifts are cards. (This does NOT mean all cards are gifts).

We deduced that "All boxes are cards". This means the set of Boxes is completely contained within the set of Cards.

However, the set of Cards could be larger than the set of Boxes. For example, there might be cards that are gifts (and thus potentially boxes), but there might also be cards that are NOT gifts (and therefore cannot be boxes, according to Statement 1).

Consider an example:

  • Let Boxes = {Book}
  • Let Gifts = {Book, Toy} (All Boxes are Gifts: {Book} <span>&sube;</span> {Book, Toy})
  • Let Cards = {Book, Toy, Letter} (All Gifts are Cards: {Book, Toy} <span>&sube;</span> {Book, Toy, Letter})

Check statements:

  • All boxes are gifts? Yes, {Book} is in {Book, Toy}.
  • All gifts are cards? Yes, {Book, Toy} is in {Book, Toy, Letter}.

Check conclusions based on this example:

  • Conclusion I: Some boxes are cards? Yes, {Book} is in {Book, Toy, Letter}. (This holds true).
  • Conclusion II: All cards are boxes? No, {Book, Toy, Letter} is not the same as {Book}. 'Toy' and 'Letter' are cards, but they are not boxes. (This does not hold true).

Since we found a scenario where the statements are true but Conclusion II is false, Conclusion II ("All cards are boxes") does not logically follow from the given statements.

Conclusion Summary

Based on our analysis:

  • Conclusion I: Some boxes are cards - Logically follows.
  • Conclusion II: All cards are boxes - Does not logically follow.

Therefore, only Conclusion I follows.

Revision Table: Syllogism Rules Applied

Statement Type Relationship In this Problem
Universal Affirmative (All A are B) A <span>&sube;</span> B (A is a subset of B) All boxes are gifts (Boxes <span>&sube;</span> Gifts)
Universal Affirmative (All B are C) B <span>&sube;</span> C (B is a subset of C) All gifts are cards (Gifts <span>&sube;</span> Cards)
Deduction (From All A are B and All B are C) Implies All A are C (A <span>&sube;</span> C) Implies All boxes are cards (Boxes <span>&sube;</span> Cards)
From All A are C Implies Some A are C Implies Some boxes are cards (Conclusion I)
From All A are C Does NOT imply All C are A Does NOT imply All cards are boxes (Conclusion II)

Additional Information: Venn Diagrams for Logic

Venn diagrams are helpful tools for visualizing the relationships described in statements and checking conclusions. For these statements:

  • Draw a circle for 'Cards'.
  • Inside the 'Cards' circle, draw a circle for 'Gifts', representing "All gifts are cards".
  • Inside the 'Gifts' circle, draw a circle for 'Boxes', representing "All boxes are gifts".

The diagram shows that the 'Boxes' circle is completely inside the 'Cards' circle. This visually confirms that "All boxes are cards" and therefore "Some boxes are cards" are true based on the premises.

The diagram also shows that the 'Cards' circle is the outermost one and is not necessarily equal to the 'Boxes' circle. There is area within 'Cards' but outside 'Gifts' (and thus outside 'Boxes'), and area within 'Gifts' but outside 'Boxes'. This visually confirms that "All cards are boxes" is not necessarily true.

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Important Questions from Conventional Syllogism

  1. Read the given statements and conclusions carefully. Assuming that the information given in the statements is true, even if it appears to be at variance with commonly known facts, decide which of the given conclusions logically follow(s) from the statements.

    Statements:

    No bank is an office.

    All offices are stalls.

    Conclusions:

    I. No bank is a stall.

    II. No stall is a bank.

    III. Some stalls are offices.

    IV. All the stalls are offices

  2. Read the given statements and conclusions carefully. Assuming that the information given in the statements is true, even if it appears to be at variance with commonly known facts, decide which of the given conclusions logically follow(s) from the statements.

    Statements:

    All flowers are beautiful.

    Vaidehi is beautiful.

    Conclusions:

    I. Vaidehi is a flower.

    II. Some beautiful are flowers.

  3. Read the given statements and conclusions carefully. Assuming that the information given in the statements is true, even if it appears to be at variance with commonly known facts, decide which of the given conclusions logically follow(s) from the statements.

    Statements:

    1. All rugs are blankets.

    2. All blankets are pillows.

    3. Some blankets are frames.

    Conclusions:

    I. All pillows are rugs.

    II. Some pillows are rugs.

    III. All rugs are frames

  4. Read the given statements and conclusions carefully. Assuming that the information given in the statements is true, even if it appears to be at variance with commonly known facts, decide which of the given conclusions logically follow(s) from the statements.

    Statements:

    Some fingers are toes.

    Some toes are rings.

    Some rings are hands.

    Conclusions:

    I. Some hands are toes.

    II. Some rings are fingers.

    III. Some hands are fingers.

    V. Some fingers are rings.

  5. Read the given statements and conclusions carefully. Assuming that the information given in the statements is true, even if it appears to be at variance with commonly known facts, decide which of the given conclusions logically follow(s) from the statements.

    Statements:

    All polygons are angles.

    All angles are diagonals.

    All cones are cubes.

    All cubes are decagons.

    No diagonal is a cube.

    Conclusions:

    I. Some diagonals are polygons.

    II. All diagonals are decagons.

    III. No polygon is a cone.

    IV. Some cubes are angles.

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