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Question

Read the given statements and conclusions carefully. Assuming that the information given in the statement 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 pillows are doors.

Some doors are beds.

Conclusions:

I. Some doors are pillows.

II. All beds are doors.

The correct answer is

Only conclusion I follows.

Understanding Syllogism Statements and Conclusions

This question asks us to analyze logical statements and determine which conclusions can be validly drawn from them. We are given two statements relating three categories: pillows, doors, and beds. We must accept the statements as true, even if they don't match real-world facts.

Analyzing the Given Statements

The statements are:

  • Some pillows are doors.
  • Some doors are beds.

These are 'Some' type statements, which indicate an overlap or intersection between the categories involved. "Some A are B" means there is at least one A that is also a B.

Evaluating the Conclusions

We need to check if the given conclusions logically follow from the statements.

The conclusions are:

  1. Some doors are pillows.
  2. All beds are doors.

Conclusion I: Some doors are pillows.

Let's look at the first statement: "Some pillows are doors." This statement establishes a relationship between pillows and doors. It means that the set of pillows and the set of doors have at least one element in common. Using basic logic, if some elements of set P are in set D, then some elements of set D must also be in set P. This is known as the converse of a 'some' statement. The converse of "Some A are B" is always "Some B are A", and it is logically valid.

Since Statement 1 says "Some pillows are doors", it directly implies that "Some doors are pillows".

Therefore, Conclusion I logically follows from Statement 1.

Conclusion II: All beds are doors.

Now let's examine the second statement: "Some doors are beds." This statement tells us there is an overlap between the set of doors and the set of beds. There is at least one door that is a bed, and conversely, at least one bed that is a door.

However, this statement does not provide any information about *all* beds. It is possible that some beds are doors, and other beds are not doors. The statement only guarantees that the intersection of doors and beds is not empty.

For example, if we represent this with sets:

  • Let P = Set of pillows
  • Let D = Set of doors
  • Let B = Set of beds

Statement 1: $P \cap D \ne \emptyset$ (Some pillows are doors)

Statement 2: $D \cap B \ne \emptyset$ (Some doors are beds)

Conclusion I: $D \cap P \ne \emptyset$ (Some doors are pillows) - This follows directly from $P \cap D \ne \emptyset$ because set intersection is commutative ($P \cap D = D \cap P$).

Conclusion II: $B \subseteq D$ (All beds are doors) - This does not follow from $D \cap B \ne \emptyset$. The intersection existing doesn't mean the entire set B is contained within D. It only means there is at least one element common to both.

Consider a scenario where there are 10 doors and 10 beds. Statement 2 ("Some doors are beds") would be true if, say, 3 doors are also beds. This means there are 3 beds that are doors. However, it doesn't tell us anything about the other 7 beds. Those other 7 beds might not be doors. So, we cannot conclude that *all* beds are doors.

Therefore, Conclusion II does not logically follow from the statements.

Summary of Conclusions

  • Conclusion I: Some doors are pillows. (Follows)
  • Conclusion II: All beds are doors. (Does not follow)

Based on our analysis, only Conclusion I follows from the given statements.

Statement/Conclusion Type Analysis Logically Follows?
Statement 1: Some pillows are doors. Some (P to D) Overlap between Pillows and Doors. N/A
Statement 2: Some doors are beds. Some (D to B) Overlap between Doors and Beds. N/A
Conclusion I: Some doors are pillows. Some (D to P) Converse of Statement 1. Valid for 'Some' statements. Yes
Conclusion II: All beds are doors. All (B to D) 'Some' relationship (D to B) does not imply 'All' relationship (B to D). No

Revision Table: Key Syllogism Rules

Understanding the valid inferences from basic statement types is crucial for solving syllogism problems.

Statement Type Example Valid Immediate Inferences (Conversion)
All A are B (Universal Affirmative) All cats are mammals. Some B are A (Some mammals are cats). The simple converse (All B are A) is not valid.
No A are B (Universal Negative) No dogs are cats. No B are A (No cats are dogs). Valid simple converse.
Some A are B (Particular Affirmative) Some students are athletes. Some B are A (Some athletes are students). Valid simple converse.
Some A are not B (Particular Negative) Some animals are not cats. No valid simple converse.

Additional Information: Venn Diagrams in Syllogism

Venn diagrams can be a helpful tool to visualize the relationships described in syllogism statements. Each category is represented by a circle. Overlapping areas show common elements.

For the given statements:

  • "Some pillows are doors": Draw two overlapping circles, one for Pillows and one for Doors. Shade or mark the overlapping area to indicate it is not empty.
  • "Some doors are beds": Draw a third circle for Beds. This circle should overlap with the Doors circle. Mark the overlap between Doors and Beds. Note that the Beds circle might or might not overlap with the Pillows circle, as the statements give no direct information about the relationship between pillows and beds.

When checking Conclusion I ("Some doors are pillows"), you look at the diagram and see that the overlap between the Doors circle and the Pillows circle is marked as non-empty. So, it follows.

When checking Conclusion II ("All beds are doors"), you look at the Beds circle. Is the entire Beds circle contained within the Doors circle? No. The diagram based on the statements only requires the overlap between Doors and Beds to be non-empty. There is room for part of the Beds circle to be outside the Doors circle. So, it does not follow.

This visual method confirms the logical derivation.

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Important Questions from 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:

    All dancers are talented.

    Some girls are dancers.

    Conclusions:

    I. Some girls are talented.

    II. All talented are girls.

    III. All girls are talented.

  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 directors are actors.

    No actor is a producer.

    All choreographers are directors.

    Conclusions:

    I. No choreographer is producer.

    II. Some actors are choreographers.

    III. No director is a producer.

  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 follows from the statements.

    Statements:

    All lemons are plums.

    All plums are dates.

    Some dates are mangoes.

    Conclusions:

    I. Some lemons are mangoes.

    II. Some mangoes are plums.

    III. All lemons are dates.

    IV. Some mangoes are dates.

  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 cards are postcards.

    Some cards are envelopes.

    All envelopes are copies.

    Conclusions:

    I. Some copies are envelopes.

    II. Some postcards are copies.

    III. Some cards are copies.

  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 employees are tax-payers.

    Some employees are farmers.

    Some farmers are doctors.

    Conclusions:

    I. No farmer is a tax-payer.

    II. Some farmers are tax-payers.

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