Syllogism by Rules Part 2 : Reversal of Sentence

Shortcut to solve syllogism by rules

Day 2 Topic: Reversal of Sentence (FIRST & LAST RULE)

 

(ii) Reversal of Proposition

Let’s start with yesterday’s example.

How to solve such statement? Here the common term is in the starting in both the proposition. For this we must know these four rules.

Original Statement Reversed Statement
All A is B Some B is A
Some A is B Some B is A
No A is B No B is A
Some A is not B No Conclusion (Reversal Not Possible)

Let’s again take example 3:
Statement (a) Some A are B
(b) All A are C
Reverse statement (a) we get => Some B are A.
Now take the proposition in the order (a), (b) we get
Some B are A. All A are B [Now common entity are together.  So FIRST & LAST RULE is applicable.]

Doubt??????
In the above example, we reversed Some A are B. Can we reverse All A is C=> Some C are A????
Then arrange the proposition in the order (b), (a) ????
Some C are A + Some A are B. [Note here also FIRSt & LAST RULE is applicable.]
But which method is correct?? First , Second or Both????

To get the answer we will discuss the preference order for reversal rule

Preference Order for reversal of statement

The table below shows the order of preference for reversal.

Order Relation Comments
1 Some, No Both Some and No have equal preference
2 All All has less preference than Some and No
3 Some Not Some Not cannot be reversed

Understand it by example.

Consider the following example:

(a) Some A are B
(b) No A are C
(c) All A are D
(d) All A are E

Example 1: Suppose we need to find relation between B and D. Then we need only proposition (a) and (c). But one of these must be reversed for FIRST & LAST RULE to be applicable.

According to above table Some has higher preference than All. So the statement with Some i.e proposition (a) must be reversed. We cannot reverse All here. So we get: Some B are A + All A are D

Example 2: Suppose we need to find relation between C and D. Then we need proposition (b) and (c) only. As per the table No has higher preference than All . So we have to reverse (b) we cannot reverse (c). So we will reverse proposition (b) and arrange in the order (b),(c) to get. No C is A + All A is C.

Example 3: Suppose we need to find relation between B and C. Then we need only proposition (a) and (b). Now Some and No both have equal preference. So we can reverse any one of them to get the desired result. i.e
Case 1: reverse (a) => Some B are A. and add it to (b)
Some B are A + No A is C
Case 2: reverse (b) => No C is A. and add it to (a)
No C is A + Some A are B

Example 4: Suppose we need to find relation between D and E. Then we need only proposition (c) and (d). here both the proposition contains ALL. So we can reverse either of them. Same as above.
Suppose we reverse (c) => Some D are A. + All A are E [FIRST & LAST RULE applicable now.]

So now our above discussed doubt has been cleared.

Practise sets for Reversal of Proposition

Example 1:
(a) Some A is B
(b) All C is B
(c) No D is A
Q1) Arrange the sentence to get a conclusion between D and B.
Solution 1) For B and C we have common term A in the proposition (a) and (c). Take them in order (c),(a) so that FIRST LAST RULE is applicable.
=> No D is A + Some A is B

Q2) Arrange the sentence to get relation between C and D.
Solution 2) Now we need to use both the rearrangement and reversal concept to achieve this goal. Follow this step:

(i) As per preference order we cannot Reverse statement (b) as it contains ALL. So fix statement as it is. (ii) Now the common entity between (b) and (a) is B. So reverse (a) so that FIRST LAST RULE is applicable.
We now have (b) + reverse(a) => All C is B + Some B is A.
(iii) Now the only proposition left is (c). The common entity between (a) and (c) is A. But for FIRST LAST RULE to be applicable (c) must be reverse.  So we have now
All C is B + Some B is A + No A is D.
(b) + reverse(a) + reverse(c)

Note: These are only for practice. When you get used to these concepts, you can simply solve the above questions in mind without using pen and paper. So practice these concepts regularly.

Example 2:
(a) All A is B
(b) No A is D
(c) All B is C

Q1) Arrange the above propositions to get a conclusion between D and C.

Steps:
(i) Note that here the highest preference is of proposition (b).On reversal it can be joined with (a) with the common entity A. So we have Reverse(a)+ (b)
(ii) Now the common entity between (a) and (c) i.e B, is already arranged. So we have: Reverse(a+(b)+ (c)

=> No D is A + All A is B + All B is C

Exercise for the Day

Direction (1-3): Using the given statements answer the following questions:

(a) No C is B
(b) All A is B
(c) Some D is C

  1. Arrange the propositions to get a conclusion between B and D
    View Answer

    Explanation
    : (c) + (a)=> Some D is C+ No C is B
  2. Arrange the propositions to get a conclusion between A and C
    View Answer

    Explanation
    : (b) + reverse(a) =>All A is B + No B is C
  3. Arrange the propositions to get a conclusion between A and D
    View Answer

    Explanation
    : (b) + rev(a)+rev(c) =>All A is B + No B is C + Some C is D

Direction (4-5): Using the given statements answer the following questions:

(a) All A is B
(b) No C is B
(c) All A is D

  1. Arrange the propositions to get a conclusion between A and C
    View Answer

    Explanation
    : (a) + reverse(b)
  2. Arrange the propositions to get a conclusion between D and C
    View Answer

    Explanation
    : reverse(c) + (a) + reverse(b)

The real Syllogism will start from tomorrow. Don’t miss any day.

Ask your doubt in comment section.

Thank You!!!!!

 

 

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60 Thoughts to “Syllogism by Rules Part 2 : Reversal of Sentence”

  1. K!nG Iz B!nG

    10x mam:)

    1. •?((¯°·._.• ąʍβɨЌą •._.·°¯))؟•

      kbhi sir ko bhi thanks bol diya kro bro 😀 ye post sir ki hai

  2. Yogi ji

    All a is b
    Conclusions = some a is B?
    Some a is B possiblty
    Some a is not b?
    Ans plz

    1. Suraj

      some a is B =>true
      Some a is B possiblty =>false
      Some a is not b =>false

      this is part of Day 4… you will get to know everything related to this on day 4

      1. Yogi ji

        Reversal statement hai ye to all a is b hta to Wrng hta because same statement follows

        1. Suraj

          what? ye jo upar revesal statement diye hai,, usse isse compare mat karo,, these two are diff things

          1. ANUP SINGH

            statement: all B are C
            some B are A
            CONC: some C are not B
            some A are not C
            some C not A a possibility
            some A not C a possibility

          2. Suraj

            some C not A a possibility
            and
            some A not C a possibility true hai baki dono false

            Day 5 ko jab possibility ka case padhenge usme sare rules post krunga isse related

          3. ANUP SINGH

            ok ty sir, possibility m sare doubts and controversies delineate kijiyega sir..

          4. Suraj

            haa,, kal se main syllogism start ho jayega.,, kal se samjh aane lagega,, first two days bas ispe based they ki kaise sentence ko arrange krna hai..

          5. ANUP SINGH

            sir jo new pattern h, usme bhi rearrangement ka concept follow krega? or krega toh fir bhi conclusion se hi statement bnana hoga?

          6. Suraj

            ha.. sabme rearrangement follow krega hi,, kyunki rules apply krne se pehle humko mind me hi sentence ko rearrange krna padega,,.. ek bar sentence rearrange ho jayega then we can apply the rules..
            and new pattern jo hai,, wo new pattern lagega hi nhi,, when u get expert in rules.. same normal ques lagega

          7. ANUP SINGH

            ty very much sir.

          8. Suraj

            ha conc se hi statement banana padega,, lekin time save hoga bohot

      2. rs

        sir Q5 b ko kyu reverse kiya ?

        1. Suraj

          Agar b) ko reverse nhi krenege to proposition a) and b) me common term B eksath nhi ayenge na

  3. •?((¯°·._.• ąʍβɨЌą •._.·°¯))؟•

    thanku suraj sir :))

      1. jaga

        all A are not B ..that means some A are not B right hoga na ?

        1. Suraj

          ye wala topic Day 5 ko full cover kr lenge

  4. paakhi

    in first –ex 1 why v r using a n c statmnts to find relation between A n D..when in statmnt C it is already writtn that all A is D

    1. Suraj

      good ques.. thats my mistake.. i will edit it.. wo All A is D nhi hoga..

        1. Suraj

          yes u got it right….

        2. Suraj

          aur koi doubt?
          concept samjh aaya kya kar rhe hai.. kyu kar rhe hai??

  5. Peacock in the Rain

    tq az

  6. HOPE_2017 ™

    Gud N8 🙂

  7. paakhi

    Example 1:
    (a) Some A is B
    (b) All C is B
    (c) No D is A
    Q1) Arrange the sentence to get a conclusion between D and C.
    Solution 1) For B and C we have common term A in the proposition (a) and (c). Take them in order (c),(a) so that FIRST LAST RULE is applicable.
    => No D is A + Some A is B

    isme b editing hogi kya sir?

    1. Suraj

      yes yes.. it will be between D and B,..
      sorry.. mistakes k wajah se confusion ho gya hoga

      1. paakhi

        sir pls read whole post again n make changes accordingly _/_

  8. paakhi

    agar suppose hme A n D k bich relation nikalna hai to kya hm ise from D to A k sequence me b arrange kr skte hai??

      1. paakhi

        agar suppose hme A n D k bich relation nikalna hai to kya hm ise from D to A k sequence me b arrange kr skte hai??.

        1. Suraj

          yes,, koi bhi ek last me ho,, koi bhi first,, farak nhi padta

        2. Suraj

          bas wo jo prefernce order hai usko dhyaan me rakh k karna arrange,, aisa na ho ki .. ALL wale sentnce ko reverse kar do..jabki NO wala reverse ho sakta ho

  9. paakhi

    nic Post ty Az learning new concept.. appreciable
    bt pls take care of mastakes in post..ty..gud nt

    1. Peacock in the Rain

      tq….gn

  10. Yogi ji

    Restatement follow hgi
    Statements=all a is b
    Conclusions =all a is b?
    Some a is b

    1. Suraj

      Yes restatement follow krta h

        1. Suraj

          Yes..
          This will be discussed on day 5

          1. Yogi ji

            Some not wale samjh nhi aate

          2. Suraj

            Day 3 ki post dekho,, usme samjhaya hai some not and some not reversed ke rules

          3. Yogi ji

            Dekhi hai aaj ki. Par ques kiye shi nhi hua

          4. Suraj

            ok, 10 Pm pe uspe discussion krenge,, ques and ans

          5. piNKmAn-debasis

            Direction (4-5): Using the given statements answer the following questions:

            (a) All A is B

            (b) No C is B

            (c) All A is D

            5.Arrange the propositions to get a conclusion between D and C

            Explanation: reverse(c) + (a) + reverse(b)

            sir arrangement toh =(b)No C is B+rev(a)Some B is A+(c)All is D bhi ho sakte hai??

          6. Suraj

            yes aise bhi ho sakta hai,, Jab statements me 2 or more ALL wale statements ho,, and unhe reverse karna pade,, to ek se jyada tarike ho sakte hai for making the correct combination… dono se answer same hi ayega lekin

          7. piNKmAn-debasis

            sir statement (b)No C is B, ka reverse karna hi hai padega,?kyunki ‘No’ 1st order me hai

          8. Suraj

            ha sabse pehle No wale ko hi reverse karo,, fir agar aise condition aaye ki ALL ko karna padega hi padgeag,, then All ko reverse karo,, jaise ki is ques me zarurat pad hi gayi..

          9. piNKmAn-debasis

            ha sir,,thanku

      1. PHENOMENAL

        Thank u sir this is very imp session, bcoz in comp!ex syllog we draw dig as it is asked in ques which become comp!ecated but by using reverse rule we can make dig easily like if it given all A is C and all A is B we can write is as some some C is A and all A is B?

  11. Dev Suman Sharma

    sir please triangles and circles ko bhi aise hi samjha dijie jaise syllogism ko samjhaya hai,,,, it was very nice

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