Logical Reasoning - Logical Deduction - Discussion

Discussion Forum : Logical Deduction - Section 3 (Q.No. 2)
Directions to Solve

In each of the questions below are given three statements followed by three conclusions numbered I, II and III, You have to take the given statements to be true even if they seem to be at variance from the commonly known facts. Read all the conclusions and then decide which of the given conclusions logically follows from the given statements disregarding commonly known facts.


2.

Statements: Some towels are brushes. No brush is soap. All soaps are rats.

Conclusions:

  1. Some rats are brushes.
  2. No rat is brush.
  3. Some towels are soaps.

None follows
Only either I or II follows
Only II follows
Only I and III follow
None of these
Answer: Option
Explanation:

Some towels are brushes. No brush is soap.

Since one premise is particular and the other negative, the conclusion must be particular negative (O-type) and should not contain the middle term. So, it follows that 'Some towels are not soaps'. No brush is soap. All soaps are rats.

Since the middle term is distributed twice, the conclusion must be particular. Since one premise is negative, the conclusion must be negative. So, it follows that 'Some brushes are not rats'. Since I and II involve the same terms and form a complementary pair, so either I or II follows.

Discussion:
13 comments Page 2 of 2.

Md. jakaria said:   1 decade ago
When no brush is soap, so there is no chance to a soap to be brushes. So a rat can be soap but no rat can be brush. Actually I have found that most of this kinds of question I failed. I would like to request you to clear me me the theory please.

Ajit said:   1 decade ago
All the conclusions are uncertain so no conclusion can be drawn so no conclusion follows.
(1)

Rishab Gupta said:   1 decade ago
Which two premises are forming complementary pairs? Please explain it in details.


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