Syllogism - Intermediate-Advanced Level: categorical logic INTERMEDIATE-ADVANCED

This fundamentals focus worksheet contains 20 intermediate-advanced-level syllogism problems. Worksheet 21 of 30 focuses on categorical logic. Practice deductive arguments, logical premises, quantifier logic with our step-by-step solutions. Difficulty: advanced concepts with increasing complexity. Recommended for advanced developing learners.

📝 Worksheet 21 of 30 • 20 questions • ⏱️ Estimated time: 20 minutes • 🎯 Intermediate-advanced level

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Worksheet 21 of 30 (70% complete)

Question 1

Statements: No electronics is a machines. All furniture are machines. Conclusions: I. No machines is a electronics. II. No furniture is a electronics. III. Some machines are not electronics.
Immediate vs Mediate Inference:

Immediate Inference: Direct conversion from one statement
Mediate Inference: Deduction requiring multiple statements

Checking Each Conclusion:

Conclusion I: "No machines is a electronics" - IMMEDIATE INFERENCE
Conversion of "No electronics is a machines" - FOLLOWS

Conclusion II: "No furniture is a electronics" - MEDIATE INFERENCE
All C are B (A) + No B is A (E) = A + E = E - FOLLOWS

Conclusion III: "Some machines are not electronics" - IMMEDIATE INFERENCE
From "No A is B", definitely some B are not A - FOLLOWS

Answer: All conclusions I, II and III follow

Question 2

Statements: All valuable are beautiful. No beautiful is a reliable. Conclusions: I. Some reliable are valuable. II. No reliable is a valuable.
Complementary Pair Concept:
Conclusions I and II form a complementary pair: "Some reliable are valuable" and "No reliable is a valuable"
These are opposite statements - at least one MUST be true.

Venn Diagram Method:
Step 1: "All valuable are beautiful" → Circle of valuable inside beautiful
Step 2: "No beautiful is a reliable" → Circles of beautiful and reliable completely separate
Step 3: Since valuable is inside beautiful, and beautiful is separate from reliable, then valuable is also separate from reliable
Step 4: Result: "No reliable is a valuable" is TRUE

Analytical Method:
All valuable are beautiful (A) + No beautiful is a reliable (E) = A + E = E = No valuable is a reliable
By conversion: No reliable is a valuable

Either-Or Case:
Since the conclusions form a complementary pair and one is definitely true, answer is "Either-Or".

Answer: Either conclusion I or II follows

Question 3

Identify the logical fallacy in the following argument: No mammals are fish. Whales are not fish. Therefore, whales are mammals. What is the primary error in this reasoning?
Fallacy Detection Analysis:

Given Argument:
No mammals are fish.
Whales are not fish.
Therefore, whales are mammals.

Type of Fallacy: Illicit Process

Explanation:
Just because whales aren't fish doesn't mean they must be mammals.

Common Syllogism Fallacies:
1. Undistributed Middle: Middle term not distributed in any premise
2. Illicit Major/Minor: Term distributed in conclusion but not in premise
3. Exclusive Premises: Two negative premises give no conclusion
4. Negative Conclusion from Positive Premises: Invalid

Correct Answer: Affirming the consequent fallacy

Question 4

Given Conclusion: No snake is a mammal Which set of statements can definitely lead to this conclusion? A. No mammal is a reptile; All snakes are reptiles B. No birds are reptile; Some unrelated are reptiles C. No snake is a mammal; All mammal are reptile D. Insufficient information
Reverse Syllogism Analysis:
Working backwards from conclusion to verify which premises support it.

Given Conclusion: No snake is a mammal

Testing Option A: No mammal is a reptile; All snakes are reptiles

Applying syllogism rules:
Statement 1: No mammal is a reptile
Statement 2: All snakes are reptiles
Combining these gives: No snake is a mammal ✓

Why Other Options Fail:
B. Random statements: No logical connection to conclusion
C. Opposite relationships: Would give contradictory conclusion
D. Insufficient: We CAN determine with proper analysis

Answer: A. No mammal is a reptile; All snakes are reptiles

Question 5

Given Conclusion: Some engineers are employed Which set of statements can definitely lead to this conclusion? A. All engineers are graduates; Some graduates are employed B. All fruits are graduates; Some unrelated are employed C. No engineers is a employed; All engineers are graduates D. Insufficient information
Reverse Syllogism Analysis:
Working backwards from conclusion to verify which premises support it.

Given Conclusion: Some engineers are employed

Testing Option A: All engineers are graduates; Some graduates are employed

Applying syllogism rules:
Statement 1: All engineers are graduates
Statement 2: Some graduates are employed
Combining these gives: Some engineers are employed ✓

Why Other Options Fail:
B. Random statements: No logical connection to conclusion
C. Opposite relationships: Would give contradictory conclusion
D. Insufficient: We CAN determine with proper analysis

Answer: A. All engineers are graduates; Some graduates are employed

Question 6

Statements: All carnivores are birds. No birds is a warm-blooded. Conclusions: I. No carnivores is a warm-blooded. II. All warm-blooded being carnivores is a possibility.
Definite Conclusion Analysis:

Venn Diagram:
Step 1: All carnivores are birds → carnivores inside birds
Step 2: No birds is a warm-blooded → birds and warm-blooded completely separate
Step 3: Since carnivores inside birds, carnivores also doesn't touch warm-blooded

Analytical Method:
All carnivores are birds (A) + No birds is a warm-blooded (E) = A + E = E
Result: No carnivores is a warm-blooded

Checking Conclusions:

Conclusion I: "No carnivores is a warm-blooded" - DEFINITE CONCLUSION - FOLLOWS

Conclusion II: "All warm-blooded being carnivores is a possibility"
Since definite negative exists ("No carnivores is a warm-blooded"), this possibility is IMPOSSIBLE
DOES NOT FOLLOW

Important Rule: When definite negative conclusion exists between terms, positive possibility becomes FALSE.

Answer: Only conclusion I follows

Question 7

Statements: Only cold-blooded are reptiles. All reptiles are herbivores. Conclusions: I. All cold-blooded are herbivores. II. Some herbivores are cold-blooded.
Understanding 'Only' Statement:
"Only cold-blooded are reptiles" means "All reptiles are cold-blooded" (reversal!)

Conversion:
Original: Only cold-blooded are reptiles
Converted: All reptiles are cold-blooded

Venn Diagram:
Step 1: "All reptiles are cold-blooded" → reptiles inside cold-blooded
Step 2: "All reptiles are herbivores" → reptiles inside herbivores
Step 3: reptiles inside both cold-blooded and herbivores

Checking Conclusions:

Conclusion I: "All cold-blooded are herbivores"
We only know reptiles is inside both - cold-blooded could be larger - DOES NOT FOLLOW

Conclusion II: "Some herbivores are cold-blooded"
All reptiles are cold-blooded and all reptiles are herbivores
The reptiles portion is common to both - FOLLOWS

Answer: Only conclusion II follows

Question 8

Statements: No invertebrates is a omnivores. All fish are omnivores. Conclusions: I. No omnivores is a invertebrates. II. No fish is a invertebrates. III. Some omnivores are not invertebrates.
Immediate vs Mediate Inference:

Immediate Inference: Direct conversion from one statement
Mediate Inference: Deduction requiring multiple statements

Checking Each Conclusion:

Conclusion I: "No omnivores is a invertebrates" - IMMEDIATE INFERENCE
Conversion of "No invertebrates is a omnivores" - FOLLOWS

Conclusion II: "No fish is a invertebrates" - MEDIATE INFERENCE
All C are B (A) + No B is A (E) = A + E = E - FOLLOWS

Conclusion III: "Some omnivores are not invertebrates" - IMMEDIATE INFERENCE
From "No A is B", definitely some B are not A - FOLLOWS

Answer: All conclusions I, II and III follow

Question 9

Statements: All nocturnal are invertebrates. Some nocturnal are amphibians. Conclusions: I. Some invertebrates are amphibians. II. All invertebrates being amphibians is a possibility. III. Some amphibians are invertebrates.
Distribution of Terms:
A term is DISTRIBUTED when statement makes claim about ALL members.
A term is UNDISTRIBUTED when statement refers to SOME members.

Statement Analysis:
Statement 1: "All nocturnal are invertebrates" → nocturnal DISTRIBUTED, invertebrates UNDISTRIBUTED
Statement 2: "Some nocturnal are amphibians" → Both UNDISTRIBUTED

Logical Deduction:
Some B are C (I) + All B are A (A) = I + A = I
Result: Some C are A OR Some A are C

Checking Conclusions:
✓ Conclusion I: "Some invertebrates are amphibians" - FOLLOWS
✓ Conclusion II: "All invertebrates being amphibians is a possibility" - No negatives exist - FOLLOWS
✓ Conclusion III: "Some amphibians are invertebrates" - Conversion of I - FOLLOWS

Answer: All conclusions I, II and III follow

Question 10

Statements: No models is a ideas. All principles are ideas. Conclusions: I. No ideas is a models. II. No principles is a models. III. Some ideas are not models.
Immediate vs Mediate Inference:

Immediate Inference: Direct conversion from one statement
Mediate Inference: Deduction requiring multiple statements

Checking Each Conclusion:

Conclusion I: "No ideas is a models" - IMMEDIATE INFERENCE
Conversion of "No models is a ideas" - FOLLOWS

Conclusion II: "No principles is a models" - MEDIATE INFERENCE
All C are B (A) + No B is A (E) = A + E = E - FOLLOWS

Conclusion III: "Some ideas are not models" - IMMEDIATE INFERENCE
From "No A is B", definitely some B are not A - FOLLOWS

Answer: All conclusions I, II and III follow

Question 11

Given Conclusion: No rose is a fruit Which set of statements can definitely lead to this conclusion? A. No flower is a fruit; All roses are flowers B. No tables are fruit; Some random are flowers C. No rose is a fruit; All flower are fruit D. Insufficient information
Reverse Syllogism Analysis:
Working backwards from conclusion to verify which premises support it.

Given Conclusion: No rose is a fruit

Testing Option A: No flower is a fruit; All roses are flowers

Applying syllogism rules:
Statement 1: No flower is a fruit
Statement 2: All roses are flowers
Combining these gives: No rose is a fruit ✓

Why Other Options Fail:
B. Random statements: No logical connection to conclusion
C. Opposite relationships: Would give contradictory conclusion
D. Insufficient: We CAN determine with proper analysis

Answer: A. No flower is a fruit; All roses are flowers

Question 12

Statements: All fish are cold-blooded. No cold-blooded is a invertebrates. Conclusions: I. Some invertebrates are fish. II. No invertebrates is a fish.
Complementary Pair Concept:
Conclusions I and II form a complementary pair: "Some invertebrates are fish" and "No invertebrates is a fish"
These are opposite statements - at least one MUST be true.

Venn Diagram Method:
Step 1: "All fish are cold-blooded" → Circle of fish inside cold-blooded
Step 2: "No cold-blooded is a invertebrates" → Circles of cold-blooded and invertebrates completely separate
Step 3: Since fish is inside cold-blooded, and cold-blooded is separate from invertebrates, then fish is also separate from invertebrates
Step 4: Result: "No invertebrates is a fish" is TRUE

Analytical Method:
All fish are cold-blooded (A) + No cold-blooded is a invertebrates (E) = A + E = E = No fish is a invertebrates
By conversion: No invertebrates is a fish

Either-Or Case:
Since the conclusions form a complementary pair and one is definitely true, answer is "Either-Or".

Answer: Either conclusion I or II follows

Question 13

Statements: Some theories are systems. All systems are strategies. Conclusions: I. All theories are strategies. II. Some theories are not strategies.
Complementary Pair Analysis:
Conclusions I and II form a complementary pair:
- "All theories are strategies" (A-type)
- "Some theories are not strategies" (O-type)
These are opposite statements where at least one can be true.

Venn Diagram:
Step 1: "Some theories are systems" → Partial overlap
Step 2: "All systems are strategies" → systems inside strategies
Step 3: The part of theories overlapping with systems is definitely inside strategies
Step 4: But we DON'T know about the rest of theories

Possible Cases:
Case 1: All of theories inside strategies → Conclusion I true
Case 2: Some of theories outside strategies → Conclusion II true

Either-Or Rule:
When conclusions form complementary pair "All" and "Some not", answer is "Either-Or".

Answer: Either conclusion I or II follows

Question 14

Statements: Some structures are frameworks. All frameworks are strategies. No strategies is a processes. All processes are concepts. Conclusions: I. Some structures are strategies. II. No frameworks is a processes. III. Some concepts are not strategies.
Complex Multi-Statement Analysis:

Statement Chain:
1. Some structures are frameworks → Partial overlap
2. All frameworks are strategies → frameworks inside strategies
3. No strategies is a processes → strategies and processes separate
4. All processes are concepts → processes inside concepts

Checking Each Conclusion:

Conclusion I: "Some structures are strategies"
Some A are B (I) + All B are C (A) = I + A = I - FOLLOWS

Conclusion II: "No frameworks is a processes"
All B are C (A) + No C is D (E) = A + E = E - FOLLOWS

Conclusion III: "Some concepts are not strategies"
All D are E (A) + No C is D (E, converted) = A + E = O* - FOLLOWS

Answer: All conclusions I, II and III follow

Question 15

Identify the logical fallacy in the following argument: No mammals are fish. Whales are not fish. Therefore, whales are mammals. What is the primary error in this reasoning?
Fallacy Detection Analysis:

Given Argument:
No mammals are fish.
Whales are not fish.
Therefore, whales are mammals.

Type of Fallacy: Illicit Process

Explanation:
Just because whales aren't fish doesn't mean they must be mammals.

Common Syllogism Fallacies:
1. Undistributed Middle: Middle term not distributed in any premise
2. Illicit Major/Minor: Term distributed in conclusion but not in premise
3. Exclusive Premises: Two negative premises give no conclusion
4. Negative Conclusion from Positive Premises: Invalid

Correct Answer: Affirming the consequent fallacy

Question 16

Statements: Some vehicles are devices. Some devices are ornaments. Conclusions: I. Some vehicles are ornaments. II. No vehicles is a ornaments.
Venn Diagram Method:
Step 1: "Some vehicles are devices" → vehicles and devices overlap partially
Step 2: "Some devices are ornaments" → devices and ornaments overlap partially
Step 3: Multiple possibilities exist:
- vehicles and ornaments may overlap (some A are C)
- vehicles and ornaments may be separate (no A is C)
- vehicles and ornaments may partially overlap

Analytical Method:
I + I combination gives NO definite conclusion.
The overlapping portions may or may not be the same part of devices.

Verification:
✗ Conclusion I: "Some vehicles are ornaments" - NOT DEFINITE (possible but not certain)
✗ Conclusion II: "No vehicles is a ornaments" - NOT DEFINITE (possible but not certain)

Answer: Neither conclusion I nor II follows

Question 17

Temporal Statements: All athletes who train regularly train for more than 6 hours daily. All athletes who win medals are athletes who train regularly. Some athletes who win medals are athletes who become famous. Conclusions: I. Some athletes who become famous train for more than 6 hours daily. II. Some people who train for more than 6 hours daily are athletes who become famous. III. All athletes who become famous are definitely athletes who win medals.
Temporal Syllogism Analysis:
Temporal syllogisms involve time-based conditions integrated with logical statements.

Logical Chain:
All athletes who win medals are athletes who train regularly + All athletes who train regularly train for more than 6 hours daily = All athletes who win medals train for more than 6 hours daily
Some athletes who win medals are athletes who become famous + All athletes who win medals train for more than 6 hours daily = Some athletes who become famous train for more than 6 hours daily

Checking Conclusions:
✓ Conclusion I: "Some athletes who become famous train for more than 6 hours daily" - FOLLOWS
✓ Conclusion II: "Some people who train for more than 6 hours daily are athletes who become famous" - Conversion of I - FOLLOWS
✗ Conclusion III: "All athletes who become famous are definitely athletes who win medals" - Only "some" given, not "all" - DOES NOT FOLLOW

Answer: Only conclusions I and II follow

Question 18

Statements: Some diurnal are nocturnal. Some nocturnal are herbivores. Conclusions: I. Some diurnal are herbivores. II. No diurnal is a herbivores.
Venn Diagram Method:
Step 1: "Some diurnal are nocturnal" → diurnal and nocturnal overlap partially
Step 2: "Some nocturnal are herbivores" → nocturnal and herbivores overlap partially
Step 3: Multiple possibilities exist:
- diurnal and herbivores may overlap (some A are C)
- diurnal and herbivores may be separate (no A is C)
- diurnal and herbivores may partially overlap

Analytical Method:
I + I combination gives NO definite conclusion.
The overlapping portions may or may not be the same part of nocturnal.

Verification:
✗ Conclusion I: "Some diurnal are herbivores" - NOT DEFINITE (possible but not certain)
✗ Conclusion II: "No diurnal is a herbivores" - NOT DEFINITE (possible but not certain)

Answer: Neither conclusion I nor II follows

Question 19

Statements: All systems are strategies. Some systems are concepts. Conclusions: I. Some strategies are concepts. II. All strategies being concepts is a possibility. III. Some concepts are strategies.
Distribution of Terms:
A term is DISTRIBUTED when statement makes claim about ALL members.
A term is UNDISTRIBUTED when statement refers to SOME members.

Statement Analysis:
Statement 1: "All systems are strategies" → systems DISTRIBUTED, strategies UNDISTRIBUTED
Statement 2: "Some systems are concepts" → Both UNDISTRIBUTED

Logical Deduction:
Some B are C (I) + All B are A (A) = I + A = I
Result: Some C are A OR Some A are C

Checking Conclusions:
✓ Conclusion I: "Some strategies are concepts" - FOLLOWS
✓ Conclusion II: "All strategies being concepts is a possibility" - No negatives exist - FOLLOWS
✓ Conclusion III: "Some concepts are strategies" - Conversion of I - FOLLOWS

Answer: All conclusions I, II and III follow

Question 20

Temporal Statements: All athletes who train regularly train for more than 6 hours daily. All athletes who win medals are athletes who train regularly. Some athletes who win medals are athletes who become famous. Conclusions: I. Some athletes who become famous train for more than 6 hours daily. II. Some people who train for more than 6 hours daily are athletes who become famous. III. All athletes who become famous are definitely athletes who win medals.
Temporal Syllogism Analysis:
Temporal syllogisms involve time-based conditions integrated with logical statements.

Logical Chain:
All athletes who win medals are athletes who train regularly + All athletes who train regularly train for more than 6 hours daily = All athletes who win medals train for more than 6 hours daily
Some athletes who win medals are athletes who become famous + All athletes who win medals train for more than 6 hours daily = Some athletes who become famous train for more than 6 hours daily

Checking Conclusions:
✓ Conclusion I: "Some athletes who become famous train for more than 6 hours daily" - FOLLOWS
✓ Conclusion II: "Some people who train for more than 6 hours daily are athletes who become famous" - Conversion of I - FOLLOWS
✗ Conclusion III: "All athletes who become famous are definitely athletes who win medals" - Only "some" given, not "all" - DOES NOT FOLLOW

Answer: Only conclusions I and II follow
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