TRIET HOC, SO 4 (227), T H A N G 4-2010
BAN THEM VE TINH CHU DIEN
CUA CAC THUAT NGUT TRONG PHAN DOAN DON
VU VAN BACH
(•)7Yn/i chu dien cua cdc thugt ngU trong phdn dodn dcfn Id mgt trong nhiing vdn di quan trgng cua logic hgc vd dUgc nhiiu tdc gid quan tdm nghien ciJCu. Trong bdi viet ndy, tdc gid dd dUa ra y kie'n ciia minh nham trao doi ve cdch lap ludn cda mgt sdtdc gid khdc ve tinh chu dien cHa cdc thugt ngU trong phdn dodn dcfn. Theo tdc gid bdi vie't, viec ldm ro tinh chu dien cua cdc thugt ngU trong phdn dodn dOn Id ca sd dethUc hien ddng cdc thao tdc logic cua phdn dodn vd suy ludn, gop phdn xdy diing tU duy logic.
C ^ an ve tinh chu dien cfla cac t h u a t ngfl rU trong p h a n doan ddn cua logic hgc hinh c / thflc hien nay cdn co nhieu y kien trai ngflde nhau. Tren T a p cbi Triet bgc so' 1/2007 CO bai cua tac gia Nguyen Nggc Ha v6i tieu de: Phdn dodn ddn trong logic hgc hinh thdc truyen thd'ng: mgt so' vdn de cdn quan tdm, cung t r e n Tap cbi Triet bgc so 1/2009 CO bai cua tac gia P h a m Quynh: Ve mgt so'ngi dung chUa nhd't qudn trong logic hgc truyen thd'ng. H a i tac gia t r e n da dUa ra y kien cua minh ve t i n h cbu dien cua cac thuat ngfl trong p h a n doan ddn. Song, toi chfla nha't tri vdi sfl ly giai cua hai tac gia ve v i n de nay. Cu the:
Hai tac gia deu k h a n g dinh hien nay co hai y kien ve t i n b cbu dien cua cac t h u a t ngfl trong p h a n doan ddn. Sfl khac n h a u cua hai y kien do la d chd: y kien thfl nha't cho rang p h a n doan A: Mgi S Id P trfldng hdp thfl nha't S chu dien, P khong cbu dien;
trUdng hdp thfl hai ca S va P deu chu dien.
Phan doan I: Mgt sdS la P trfldng hdp thfl nha't ca S va P deu khdng chu dien; trUdng hdp thfl hai S khdng chu dien, P chu dien.
Y kien thfl h a i chi thfla n h a n trfldng hdp thfl nha't cua p h a n doan A va p h a n doan I.
Nhfl vay, sfl khac n h a u cua h a i y kien dd la thfla n h a n va khdng thfla n h a n P co trfldng hdp chu dien trong p h a n doan A va I. Ddng thdi, hai tac gia deu cho r a n g y kien thfl hai
la dflng, song sfl luan giai cua hai tac gia co diem chUa t h u y e t phuc.
Tac gia N g u y i n Nggc Ha lap luan: " C i n thfla n h a n r i n g , trong phep doi cho (dao ngflde) cua suy l u a n dien dich trflc tiep tfl tien de la mgt p h a n doan ddn c6 4 cong thflc dung va 4 cong thflc sai, trong suy luan dien dich gian tiep tfl tien de la bai phan doan ddn c6 c6 24 cong thflc dung va 232 cong thflc sai"(l) de tfl do k h a n g dinh P khong chu dien trong p h a n doan A va I. Su lap l u a n nay la chUa thuyet phuc; bdi vi, de xet tinb cbu dien cua cac t h u a t ngfl trong p h a n doan ddn ta phai khao sat trUc tiep ngoai dien cua cac k h a i niem dUdc sfl dung trong do. Can cfl vao t i n b cbu dien cua cac t h u a t ngfl trong p h a n doan ddn ta mdi suy r a dfldc cdng thflc ddi cho trong suy luan d i l n dich trflc tiep tfl tien de la mgt phan doan ddn va suy l u a n d i l n dich gian tiep tfl tien de la hai p h a n doan ddn (tam doan luan), chfl khdng the lam ngflde lai n h u tac gia N g u y i n Nggc Ha quan niem. Tac gia N g u y i n Nggc Ha can cfl vao cong thflc trong phep ddi chd tfl tien de la mgt phan doan ddn va cdng thflc cua t a m doan luan de xac dinb t i n h chu dien cua cac t h u a t ngfl
(*) TrUdng Si quan Chinh tri, Bic Ninh.
(1) Nguyin Ngpc Ha. Phdn dodn dOn trong logic hgc hinh thUc truyin thdng: mgt so vdn de cdn quan tdm. Tap chi Triet hpc, sd 1/2007, tr.61.
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trong p h a n doan ddn. Sai l i m cua tac gia cdn d chd q u a n niem ve cdng thflc suy l u a n d i l n dich dflng va cdng thflc suy l u a n dien dich sai. K h a n g dinh cua tac gia chUa chat che d cho, cong thflc suy l u a n dien dich nao dung va cong thflc suy l u ^ n dien dich nao sai phai dfldc k h a o s a t trong tflng trfldng hdp cu the. De suy r a cdng thflc ddi chd cua suy l u a n d i l n dich trflc tiep tfl tien de la mgt p h a n doan ddn, t a p h a i can cfl vao quy t i c doi cho (nhfl tac gia da chi ra, trong do CO ap dung t i n h chu dien cua cac t h u a t ngfl trong p h a n doan ddn) de k h a o sat. Tac gia Nguyen Nggc Ha cho r i n g , vdi p h a n doan A Mgi S Id P ddi chd ne'u dUdc p h a n doan: Mgi P la S la sai. K h a n g dinh n a y h o a n toan khdng chinb xac; bdi vi, neu trUdng hdp S va P CO q u a n he ddng n h a t thi ddi cho p h a n doan A t a h o a n toan dfldc p h a n doan: Mgi P la S. Sfl dflng d i n nay khdng phai la ngau nhien, vi xet q u a n h e ve ngoai dien gifla S va P CO the xay r a cac trfldng hdp S va P tach rdi n h a u ; S va P p h u thugc vdi n h a u ; S va P giao n h a u ; S va P ddng n h a t vdi n h a u .
Tfldng tfl nhfl vay, vdi p h a n d o a n I:
Mgt so'S Id P, t a c gia N g u y i n Nggc H a cung cho r i n g n e u ddi chd dUdc p h a n doan: Mgi P Id S la sai. K h i n g d i n h n a y cung k h d n g c b i n h xac, bdi n e u P co q u a n he p h u t h u g c vdi S t h i cdng thflc t r e n h o a n t o a n dflng. Sfl dflng d a n n a y c u n g khong p h a i la n g a u n h i e n ma xet t r o n g tflng trUdng hdp cu t h e q u a n h e ve ngoai dien gifla h a i k h a i n i e m S va P . Nhfl vay, t a c gia da sfl d u n g l u a n cfl s a i de chflng m i n h cho y k i e n cua m i n h la dflng. Ro r a n g , each l a p l u a n nhfl vay la k h d n g t h u y e t p h u c , vi p h a m q u y t i c cd b a n cua p h e p chflng m i n h t r o n g logic hgc.
Vdi t a m doan luan, de c6 mgt cdng thflc dflng phai t u a n theo cac dieu kien cdn va du la: dieu kien c i n la t a m doan l u a n p h a i t u a n theo 8 quy t i c (8 quy t i c nhfl tac gia da k h i n g dinh); dieu kien du la tien de cua
t a m doan l u a n p h a i c h a n thUc. Cdn trUdng hdp tien de c h a n thflc nhflng vi p h a m 1 t r o n g 8 quy t i c m a k e t l u a n c h a n thflc la trfldng hdp n g a u n h i e n . Nhfl vay, tac gia da thfla n h a n cac quy t i c cua mgt t a m doan l u a n dflng nhflng k h i v a n d u n g de khao sat mgt cdng thflc suy l u a n dien dich thi lai khdng t u a n t h u cac quy t a c nay. Dang thflc A E E m a tac gia cho r i n g h o a n toan sai d loai h i n h mgt, ve t h i thflc chat, nd chi sai trong trfldng hdp P t r o n g p h a n doan A khdng chu dien, cdn trfldng hdp P trong p h a n doan A chu dien thi d a n g thflc tren v a n dung. NhUng tac gia lap l u a n r i n g , vdi mdi cong thflc sai "chung t a deu tim dfldc it nha't mgt trfldng hdp m a d dd S, P, M dfldc t h a y b i n g 3 k h a i n i e m cu t h e sao cbo tien de la p h a n doan dflng nhflng ket l u a n lai la p h a n doan sai"(2) de chflng m i n h cho dang thflc A E E sai d loai h i n h mgt, t h i thflc chat tac gia da k h d n g k h a o s a t b e t t a t ca cac trfldng hdp cd t h e xay r a t r o n g q u a n he ve ngoai dien gifla S va P cua p h a n doan A.
N h u vay, l u a n cfl tac gia n e u len de chflng m i n h cho P k h d n g chu dien trong phan doan A la k h d n g t h u y e t phuc.
T a c gia P h a m Q u y n h d a d i n r a cac k h a i n i e m k h a c n h a u ve t i n h c h u dien c u a cac t h u a t ngfl t r o n g p h a n d o a n ddn.
N h a n t h a y r i n g cac k h a i n i e m cua cac t a c gia k h a c n h a u d e u cd each p h a t bieu r i e n g , song b a n c h a t v a n de k h d n g k h a c n h a u ( t r o n g n h f l n g k h a i n i e m dd t h i k h a i n i e m c u a t a c gia Td D u y Hdp va N g u y i n A n h T u a n la d l h i e u , d l ap d u n g nha't)(3). Dflng nhfl t a c gia P h a m Q u y n h q u a n n i e m , " t r o n g p h a n doan, m g t t h u a t ngfl dfldc ggi l a c h u d i e n k h i t h u a t ngfl do de c a p tdi t a t c i (chu) cac t h a n h vien (ngoai dien) cua Idp m a nd dai
(2) Nguyin Ngoc Ha. Phdn dodn dan trong logic hgc hinh thiic truyen thd'ng: mgt so' vd'n de cdn quan tdm. Sdd., tr.61.
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di$n"(4). N h u n g tiec r i n g , k h i khao sat tinh chu dien cua S v a P trong 4 loai p h a n doan ddn A, E, I, O, tdc gia lai khong t u a n t h u chinh quan niem cua minh. Cu the la d trfldng bdp P trong p h a n doan A va I. Tac gia dfla r a q u a n diem: "Hai yeu to' q u a n trgng n h i t de xac dinh t i n h chu dien cua cac t h u a t ngfl trong p h a n doan ddn la chat va Ifldng cua p h a n doan. LUdng cua p h a n doan de xac dinh t i n h chu dien cua chu tfl (Ifldng toan the thi chu tfl chu dien va ngflde lai, Ifldng bg p h a n tbi chu tfl khong chu dien); chat cua p h a n doan de xac dinh tinh chu dien cua vi tfl (chat p h u dinh thi vi tfl chu dien, chat k h a n g dinb tbi vi tfl khong chu dien)"(5) de lam can cfl khao sat tinh chu dien cua cac t h u a t ngfl trong p h a n doan ddn. Dieu nay la khong chinb xac, vi no khong t u a n t h u dflng k h a i niem ve tinb chu dien cua cac t h u a t ngfl trong p h a n doan ddn. Do do, lap l u a n de k h a n g dinh P khong chu dien trong p h a n doan A va I cua tac gia P h a m Quynh la chUa cbinh xac.
Trong p h a n doan A, de lap l u a n P khong chu dien (trUdng hdp S va P co quan be ddng nha't), tac gia viet: "Ham y cua p h a n doan A la n h a m xac dinb ta't ca mgi t b a n b vien cua tap S co la t b a n b vien cua tap P hay khong, chfl khdng q u a n t a m mgi t b a n b vien cua P cd la t h a n h vien cua S hay khong. Vi du, trong p h a n doan "Mgi hinh vuong la h i n h chfl n h a t co chieu dai bon canh b i n g nhau", ngoai dien cua S va P dong nha't vdi n h a u , nhUng mgi S Id P vd mgi P cung Id S khong cd nghla Id P cdng phdi chu diin nhU S"(6) (tac gia nha'n manh - V.V.B). NhUng k h i khao sat p h a n doan I: mgt sd S la P, tac gia chi ra "S khong chu dien vi nd chi de cap den "mgt so" ma khdng p h a i "tat ca" (dieu nay la dung) nhUng de chi r a P khdng chu dien tac gia viet: "Hai p h a n doan "Mgt sd S la P" va
"Mgt sd P la S" tUdng dUdng logic vdi nhau"(7). Theo toi hieu, tac gia co ngam y P
khong chu dien vi cflng chi dUdc de cap tdi
"mgt so". N h u vay, lap l u a n de di tdi k h i n g dinh P khong chu dien trong p h a n doan A va I cua tac gia P h a m Quynh la khong n h a t q u a n va gUdng ep. Bdi vi, neu d p h a n doan I
"Mgt so' S la P ' tac gia chi ra p h a n doan
"Mgt sd P la S" la tUdng dfldng logic de k h a n g dinh ca S va P khdng chu dien vi chi dUdc de cap tdi 'mgt so" doi tUdng thugc ngoai dien cua t h u a t ngfl do, thi dfldng nhien ngfldi dgc hoan toan co the suy luan tfldng tfl nhfl vay vdi p h a n doan A "Mgi S la P" cung se tUdng dUdng logic vdi phan doan
"Mgi P la S" trong trUdng hdp S va P c6 quan he ddng nba't (trflng khit ve ngoai dien). Do do, se khang dinb ca S va P deu chu dien -vi no de cap tdi "ta't ca" cac doi tUdng thugc ngoai dien cfla ca S va P chfl khong p h i i "mgt so", dflng nhU pbUdng phap ma tac gia da sfl dung vdi phan doan 1.
Nhu vay, ca hai tac gia Nguyen Nggc Ha va P h a m Quynh deu co sai l i m khi khong cong n h a n P trong p h a n doan A va 1 c6 trfldng hdp chu dien. NgUdc lai, P hoan toan CO chu dien trong p h a n doan A va I khi xet cu the chfl khong phai chi la ngau nhien. Sai l i m nay la do hai tac gia khong t u a n t h u dung khai niem ve tinh cbu dien cfla cac t h u a t ngfl trong phan doan ddn va khong khao sat cu the quan he ve ngoai dien cua tflng S va P trong cac trfldng hdp cu the.
Giai quyet va'n de nay, ta xet: (Ddi tfldng dfldc p h a n doan de cap la p h i n gach cheo).
- P h a n doan A: Mgi S la P
-I- Neu S CO q u a n he phu thugc vdi P thi (3) Pham Quynh. Ve mgt so' ngi dung chUa nhd't qudn trong logic hgc truyen thd'ng. Tap chi Triet hpc, so 1/2009, tr.61.
(4) Pham Quynh. Ve mgt sd ngi dung chUa nhdt qudn trong logic hgc truyen thd'ng. Sdd., tr.62.
(5) Pham Quynh. Ve mpt sd npi dung chUa nhdt qudn trong logic hgc truyen thdng. Sdd., tr.62.
(6) Pham Quynh. Ve mgt sd npi dung chUa nhdt qudn trong logic hgc truyin thdng. Sdd., tr. 63.
(7) Pham Quynh. Vi mot sd npi dung chUa nhat qudn trong logic hgc truyen thdng. Sdd., tr. 63.
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S chu dien, P khdng chu dien. S cbu dien vi ngoai dien cua no dUdc de cap tdi "ta't ca"; P khong chu dien vi ngoai dien cua P cbi dUdc de cap tdi mgt bg p h a n , ngoai dien cua P bao gdm p h i n gach cheo va p h a n de t r a n g . Trong trUdng bdp tren, no mdi chi dUdc de cap tdi mgt bg p h a n la p h i n gach cheo ; do do, P khong chu dien. VI du: " T i t ca kim loai deu d i n dien" thi "kim loai" (S) dUdc chu dien vi p h a n doan A neu len toan bg ngoai dien cua k h a i niem "kim loai" con
" d i n dien" (P) khong chu dien vi cbi co
"kim loai" la chat dan dien dUdc de cap tdi trong p h a n doan dd, ngoai "kim loai" r a cdn mgt so' chat khac nhfl "nfldc" cung cd the
"dan dien" nhUng khdng dUdc de cap tdi trong ngoai dien cua k h a i niem "dan dien".
+ Neu S va P c6 q u a n he dong nba't (trung khit) thi ca S va P deu chu dien. S chu dien vi ngoai dien cua no dfldc de cap tdi
"ta't ca"; P cflng chu dien vi ngoai dien cua P trflng vdi ngoai dien cua S, ma ngoai dien cua S da dfldc de cap tdi "ta't ca" nen ngoai dien cua P cung dUdc de cap tdi "ta't ca".
Vi du: "Tam giac deu la t a m giac co ba canh b i n g nhau"; " N g u y i n Du la tac gia Truyen Kieu".
- P h a n doan I: M g t s d S l a P
+ Neu S va P CO quan he giao n h a u thi ca S va P deu khong chu dien. S khong chu dien vi ngoai dien cua no chi dUdc de cap tdi "mgt sd' doi tUdng; P cung khong chu dien vi ngoai dien cua P bao gdm p h i n gach cheo va p h i n de t r i n g , trong trUdng hdp nay nd mdi chi dugc de cap tdi "mgt so' ddi tUdng trong p h a n
doan I la p h i n gach cheo. Vi du: "Mgt sd anh biflig lao dgng la cdng n h a n " thi chi cd mgt bg p h a n "anh hflng lao dgng" (S) va mgt bg phan
"cdng n h a n " (P) trong p h a n doan dd dUdc de cap tdi trong ngoai dien cua bai khai niem tren nen ca S va P khdng chu dien.
+ N e u P cd q u a n h e p h u thudc vdi S thi S khong chu dien con P chu dien. S khong cbu dien -vi ngoai dien cua no cbi dUdc de cap tdi "mgt sd^' ddi tUdng t r o n g p h a n doan I, ngoai dien cua S bao gdm p h a n de t r i n g va p h i n gach cheo, trUdng hdp t r e n nd mdi chi dUdc de cap tdi mgt bg p h a n la phan gach cheo; P chu dien vi ngoai dien cua no cbi bao gdm p h i n gach cheo, p h a n nay cung chinh la doi tUdng dUdc p h a n doan I phan a n h n e n t r o n g trUdng bdp t r e n t a se co p h a n doan Mgi P Id S se tUdng dUdng v6i gia t r i logic cua p h a n doan Mdt so'S Id P, do do ngoai dien cua P dUdc de cap t6i "ta't ca" n e n nd dfldc chu dien. Vi du: "Mgt so' rflng la rflng n g u y e n sinh" thi chi c6 mgt bg p h a n "rflng" (S) dfldc de cap n e n no khong chu dien, cdn "rflng n g u y e n sinh" (P) dfldc de cap tdi ta't ca n e n nd dfldc chu dien.
Tom lai, de xac dinh tinh chu dien cua cac t h u a t ngfl trong p h a n doan ddn noi chung, trong p h a n doan A va I ndi rieng can phai can cfl vao k h a i niem chu dien va khao sat q u a n be ve ngoai dien gifla cac thuat ngfl S va P de xac dinb. Viec lam rd tinb cbu dien cua cac t h u a t ngfl trong p h a n doan ddn la cd sd de thflc hien dflng cac t h a o tac logic cua p h a n doan va suy luan, gdp p h a n xay dung t u duy logic cbo mdi ngUdi. •
