Logical Deduction - Section 1
Practice and master this topic with our carefully crafted questions.
In each question below are given two statements followed by two conclusions numbered I and II. You have to take the given two statements to be true even if they seem to be at variance from commonly known facts. Read the conclusion and then decide which of the given conclusions logically follows from the two given statements, disregarding commonly known facts.
Give answer:
(A) If only conclusion I follows
(B) If only conclusion II follows
(C) If either I or II follows
(D) If neither I nor II follows and
(E) If both I and II follow.
Statements: All fishes are grey in colour. Some fishes are heavy.
Conclusions:
I. All heavy fishes are grey in colour.
II. All light fishes are not grey in colour.
Since one premise is particular, the conclusion must be particular and should not contain the middle term. So, it follows that 'Some heavy things are grey in colour'. I is a cumulative result of this conclusion and the first premise. Thus, only I holds.
Statements: All good athletes win. All good athletes eat well.
Conclusions:
I. All those who eat well are good athletes.
II. All those who win eat well.
Since the middle term 'good athletes' is distributed twice in the premises, the conclusion must be particular and should not contain the middle term. So it follows that 'Some of those who win, eat well'.
Statements: All film stars are playback singers. All film directors are film stars.
Conclusions:
I. All film directors are playback singers.
II. Some film stars are film directors.
Since both the premises are universal and affirmative, the conclusion must be universal affirmative and should not contain the middle term. So, I follows. II is the converse of the second premise and so it also holds.
Statements: All hill stations have a sun-set point. X is a hill station.
Conclusions:
I. X has a sun-set point.
II. Places other than hill stations do not have sun-set points.
Since both the premises are universal and affirmative, the conclusion must be universal affirmative and should not contain the middle term. So, only I follows.
Statements: Some dreams are nights. Some nights are days.
Conclusions:
I. All days are either nights or dreams.
II. Some days are nights.
Since both the premises are particular, no definite conclusion follows. However, II is the converse of the second premise and thus it holds.
Statements: All jungles are tigers. Some tigers are horses.
Conclusions:
I. Some horses are jungles.
II. No horse is jungle.
Since the middle term 'tigers' is not distributed even once in the premises, no definite conclusion follows. However, I and II involve only the extreme terms and form a complementary pair. So, either I or II follows.
Statements: Raman is always successful. No fool is always successful.
Conclusions:
I. Raman is a fool.
II. Raman is not a fool.
Since both the premises are universal and one premise is negative, the conclusion must be universal negative and should not contain the middle term. So, only II follows.
Statements: Some desks are caps. No cap is red.
Conclusions:
I. Some caps are desks.
II. No desk is red.
Since one premise is particular and the other premise is negative, the conclusion must be particular negative and should not contain the middle term. So, it follows that 'Some desks are not red'. However, I is the converse of the first premise and thus it holds.
Statements: Some hens are cows. All cows are horses.
Conclusions:
I. Some horses are hens.
II. Some hens are horses.
Since one premise is particular, the conclusion must be particular and should not contain the middle term. So, II follows. I is the converse of II and so it also holds.
Statements: All water is divine. All temples are divine.
Conclusions:
I. All water is temple.
II. All temples are water.
Since the middle term 'divine' is not distributed even once in the premises, no definite conclusion can be drawn.