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
- Arrange the propositions to get a conclusion between B and D
- Arrange the propositions to get a conclusion between A and C
- Arrange the propositions to get a conclusion between A and 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
- Arrange the propositions to get a conclusion between A and C
- Arrange the propositions to get a conclusion between D and C
The real Syllogism will start from tomorrow. Don’t miss any day.
Ask your doubt in comment section.
Thank You!!!!!
10x mam:)
kbhi sir ko bhi thanks bol diya kro bro 😀 ye post sir ki hai
All a is b
Conclusions = some a is B?
Some a is B possiblty
Some a is not b?
Ans plz
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
Reversal statement hai ye to all a is b hta to Wrng hta because same statement follows
what? ye jo upar revesal statement diye hai,, usse isse compare mat karo,, these two are diff things
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
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
ok ty sir, possibility m sare doubts and controversies delineate kijiyega sir..
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..
sir jo new pattern h, usme bhi rearrangement ka concept follow krega? or krega toh fir bhi conclusion se hi statement bnana hoga?
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
ty very much sir.
ha conc se hi statement banana padega,, lekin time save hoga bohot
sir Q5 b ko kyu reverse kiya ?
Agar b) ko reverse nhi krenege to proposition a) and b) me common term B eksath nhi ayenge na
ok
thank u sir
thanku suraj sir :))
sir…
yess
all A are not B ..that means some A are not B right hoga na ?
yes.. right
ye wala topic Day 5 ko full cover kr lenge
Ok sir..
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
good ques.. thats my mistake.. i will edit it.. wo All A is D nhi hoga..
then B n D?
yes u got it right….
aur koi doubt?
concept samjh aaya kya kar rhe hai.. kyu kar rhe hai??
lil bit
tq az
Gud N8 🙂
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?
yes yes.. it will be between D and B,..
sorry.. mistakes k wajah se confusion ho gya hoga
sir pls read whole post again n make changes accordingly _/_
ok
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??
@sir
yess
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??.
yes,, koi bhi ek last me ho,, koi bhi first,, farak nhi padta
ok
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
nic Post ty Az learning new concept.. appreciable
bt pls take care of mastakes in post..ty..gud nt
tq….gn
Restatement follow hgi
Statements=all a is b
Conclusions =all a is b?
Some a is b
Yes restatement follow krta h
Pkka
Yes..
This will be discussed on day 5
Some not wale samjh nhi aate
Day 3 ki post dekho,, usme samjhaya hai some not and some not reversed ke rules
Dekhi hai aaj ki. Par ques kiye shi nhi hua
ok, 10 Pm pe uspe discussion krenge,, ques and ans
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??
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
sir statement (b)No C is B, ka reverse karna hi hai padega,?kyunki ‘No’ 1st order me hai
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..
ha sir,,thanku
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?
sir please triangles and circles ko bhi aise hi samjha dijie jaise syllogism ko samjhaya hai,,,, it was very nice