Lý thuyết tăng trưởng PGS TS đàm xuân hiệp

Trong khi nha kinh to hoc Domar chi-mg minh tinh thiet yeti ye van de 1u9ng tu ban va sac san xuat phai tang trudng theo m0t tS, le khOng d6i thi ngagc lai, nha kinh to hoc Harrod lai ch

PGS TS DAM XUAN HIEP

Lt rrnuykr TANG TRIJONG

iii

NHA XUAT BAN KHOA HOC VA 1(17 THU lAT

HA NOI - 2010

Lol N61 Mill

Tang tru6ng luOn la chii de ciia nhieu cuOc tranh luan khac nhau gida nhieu nha kinh to hoc, giira nhieu tm6ng phai hoc thuyet khac nhau DO cling la van de dapc nhieu nha nghien cdu cling nhu thkrc hanh chinh sach

vi me quan tam

Tim du'oc ban chat citing clan cna tang truCing co the gitip Ich cho cac nha hoach dinh va ra guy& dinh chInh sach kinh to cua mot qu6c gia Cu6n sach nay dua ra mot gOc nhin ye ban chat dm tang tru6ng

Thoat dau, cuon sach dupe bien soar' nham phuc vu mot phan cho cac bai giang trong mOn chuyen de to chpn "1/ thuyet kinh to dOng" ma tac gia thtic hien tai mot so khod cao hoc nganh Quan tri Kinh doanh cua truerng Dai hoc Bach Khoa Ha NOi Tuy nhien, tai lieu cling co the duorc dimg de phuc vu hoc tap cho sinh vien va cac can 1D0 nghien cau cua cac chuyen nganh khac lien quan den kinh to hoc vi mo nhu: kinh to cOng nghiep, kinh

to nang lacing._ CuOn sach bao g6m nhang not dung co ban nhu sau:

Chuang I: Tang trua'ng can bang

Chuang 2: Nguyen ttic yang caa tang trtang vci van de' phan chic

thu nhap

Chuang 3: Phdn tich them ve ccich nhin tan co

Chuang 4: Tang tniong phi can bang

Chuang 5: Tang truang nOi sinh va tang truang ngoai sinh

Chuang 6: Cac mo hitzh phi can bang

Chuang 7: Ccic !no hinh can bang

Day la Ian xuat ban dau tien nen có the cuein sach khOng tranh dugc thieu sot v6 not dung lan hInh thdc trInh bay Chung tOi rat mong nhan dtroc cac y kien &rig gop cUa dpc gia de nang cao chat luong cu6n sach trong Lan tai ban tiep theo Noi tie'p nhan cac Y kien: Nha xuat ban Khoa hoc va Ky thuat - 70 Tran Hung Dao - Ha NQi; hoac dia chi email: hiepdx(&epu.edu.vn

Tran trong cam on!

Tdc gid

TANG TRUING CAN BANG

Trong thuyet "can bdng tang guar cUa Keynes, Ong da gia thiet

rang lacing dkr trfr tu ban khOng d6i va dpc lap vOi dau to trong 14 Trong

mO hinh "khd Wang tang tradng can bdng", Keynes cling da dua vao hai

nhan t6 "cung" dau tu (tang truOng kha nang san xugt tuong lai) va

su tac Ong taping 116 dPng gifta "cung" va "cau" (tac Ong cUa he s6 tang t6c) Dim vao hai nhan t6 co ban nay, Keynes da xay dung cac hoc thuyet hien dai ye tang truOng kinh to va cac hoc thuyet ye chu trinh Nhieu tac gia sau nay ding dd dung cac gia thiet cUa Keynes de nghien cdu qua trinh phat tridn ho4c tang truOng

Gang nhu vay, lan dau tien vao nam 1936, nha kinh to hoc Kalecki

Et de cap den nhung khai niem co ban ye hoc thuyet chu trinh dip trC,'n hai nhan to "cung" va "cau" Sau do, nha kinh to hoc Samuelson ti6p tuc nghien cau van de nay Tiep theo, hai nha kinh to hoc not tieng Harrod va Domar da phat tridn hoc thuyet nay IT* cach town dien va hoan chinh

Nhieu nha kinh to da g9i chung day la mO hinh "Harrod - Domar" MO

hinh nay da dua ra mot 56 dac tinh cling nhu cac diet' kien cho qua trinh tang truOng can bang

1.1 BAN CHAT "KEP" COA DAU TU

Mpt nen kinh to luOn luOn chiu tac dpng dong thei cUa cling va cau tir qua trinh dau tu, va to goi nom na la "tac dOng kep" Qua nhan t6

"cau" (s6 nhan), dau to xac Binh duoc tang thu nhap va tang cau; con qua

nhan t6 "cling", dau tu ding lam tang truOng nang ivy san xufft

Cau

Xac dinh eau (s6 nhan)

Tang cau Al

Ben canh clueing cau, dau tu cung xac dinh auk thu nhap thOng qua s6 nhan Keynes Mat khac, tang tru6ng cau phu thuOc vao mac bien thien trong dau tu Ta c6 the tham khao hinh 1.1 sau day:

Dau ttr ren2 I Cung

Tang tradt g tu ban

AK =1

Can bang A/ s

— = — / v

Hinh /./ Hai tac nhan ctia dau tu

• D6i voi duong cung: d6 la tong dciu tu cho phep xac dinh mac dO tang truOng (/)

• D6i vai duong cau: do la mac tang tru&ng dfiu to Al

Do vay, neu ngay hOm nay ta dau tu mot khoan lien nham dieu chinh cau theo nang luc san xuat thi ngay mai ta can phai dau tu nhieu hem n[ra b6i vi chi c6 dau tu moi thuc su lam tang nang luc san xuat (Domar)

De duy tri mitt can bang giila tang cung va tang cau, ta can phai thus su quan tarn den dau tu Do vay, muc dau tu can tinh town hop ILT de lucrng ta ban va sCrc san xuat se tang tru6ng ved mot tSf le khOng d6i va bang t37' s6 gitla lai suat tiet kiem so v6i he se; tu ban Do vay, khi ta c6 mot khoan dau ta reng thi dieu do c6 nghia la nang luc san xuat se tang truOng; can bang gida du6ng cung va dung cau chi la can bang ta khOng the c6 can bang nao khac ngoai sit' tang tru'dng da du' c can bang,

ding c6 nghia la khOng c6 can bang fia

Trong khi nha kinh to hoc Domar chi-mg minh tinh thiet yeti ye van

de 1u9ng tu ban va sac san xuat phai tang trudng theo m0t tS, le khOng d6i thi ngagc lai, nha kinh to hoc Harrod lai chi ra rang, ban chat cna tang truOng kinh to la khOng on dinh Tir lap luan nay, Harrod da dat ra hai cau h6i:

• MOt la, tinh on dinh cua su tang twang can bang

• Hai la, kha nang duy tri mot xa hoi c6 day du tong an viec lam

1.2 TINH PHI ON DINH CCM TANG TRIfoNG

Bang viec dua ra khai niem ye tang trudng du kien trong qua trinh xac dinh lacing dau tu, nha kinh to hoc Harrod da rut ra ket luan: ban chat cUa mei quan he tru6c day xac dinh t57 le tang truOng so \Jai 6/' le gida lai suat ti& kiem va he s6 ta ban la khOng on dinh Tuy nhien, tren thuc cac bai via dm Harrod van chug cung cap day di' cach chdrig minh ro rang ve tinh phi 6n dinh cna su tang trudng, them chi Harrod cling khOng neu duot nguyen nhan cita tinh phi 6n dinh nay Van de mJ nay da du6c nhieu nha kinh to hoc quan tarn nghien cdu tiep va ho da chung minh dugc rang, v6 thuc chat, tinh phi on dinh Harrod cling chinh la tinh phi 6n dinh cUa he s6 tang tCic trong thuyet chu trinh: viec dieu chinh kip died he

se dau tu se clan den ITHIC Bien d'Ong cua cau va attic Wen clOng cUa nang luc sari xuat khOng bie'n thien theo cung mot tri s6

• Tang truerng cau

Hinh 1.2 Tinh phi b6n vting Harrod

a) Tang triang can bang ; b) Tinh phi ben yang

Bay gio to gia thief rang cdc chu doanh nghiep do kien t6c de tang twang bang 6% Nhu vay, de nang lot san xuat tang 6% thi tY le dau tu can phai tang fir 10% den 12% Mat khdc, de tang 1% nang luc san xuat (L.-mg v6i Mat tang truong chung tit 5% den 6%) thi dau tu can phai tang 20% Do tdc Ong ciia he s6 tang t6c, mac tang them dm eau xuat phat to ink tang them ciia dau to cling se bang 20% Nhu vay, mire tang truong cung tif 5% den 6%, con mac tang truong cau tit 5% den 25% (hinh 1.2b) Do (16, cac nha doanh nghiep se can phai tang dau tu de bit dap mac chenh Lech giCra cung va cau; nen kinh to hu6ng va dat t6i su bong n6 v6 toc dO tang truong Nguqc lai, neu t6c de tang truong throe du kien thap hon 5% thl dieu nay clan den met &rang cau qua yeu kern, va nhu vay nen kinh to se phai dei mat v6i so suy thodi co the

Vi du nay da neu re nguyen nhan cua tinh phi 6n dinh: tdc Ong dm

he s6 tang toc dau tu khOng clang met tri s6 vei tdc Ong dia he s6 nay len tee do tang truong cung (tic Ong dm he se tang t6c) ngoai tar dei voi met gia tri hang hod rieng biet king v6i the de tang truong can bang

Do do tdc deng cila he se tang t6c se qua cao bOi hai 17 do: thir nhat, mO hinh tang truong nay da be qua cdc nhan t6 ngoai sinh cua (long cau (cdc chi phi cung Ong, xuat khaki, dau to trong nuoc va dau tu thay the); thd hai, m6 hinh nay cung bO qua th6ng s6 thei han hieu chinh ma thOng s6 nay c6 tdc dung lam on dinh hod he s6 tang t6c

1.3 TANG TRLONG KINH -ft VA VleC LAM

Van de did hai ma nha kinh to hoc Harrod neu ra, do la so tic Ong qua lai gida tang truong kinh to va met xa 110i day du viec lam Bang cdch dua ra nhirng lap Juan nguoc lai voi hoc thuyet "tY le tang truong bdo ddin"(tY le nay lam can biting cung va cau tren thi truing hang hod con tY

le tang truong to nhien cho phep duy tri so can bang thi twang lao &Ong), thi met nghich ly xuat hi0: "so dOi lap gida hoc thuyet Keynes va hoc thuyet c6 diL"

Neu tji le tang truong bao dam g„, cao hon t57 le tang truong to nhien, nen kinh to c6 the cho phep c6 met t6c de tang truong cao, vi du

nhu sau su suy thoai chung tram trong cUa mot nen kinh te", c6 the cho phep lam giam b6t nan that nghiep:

Nhung khi nen kinh to huong tai viec tao day dU cOng an viec lam cho ngtred lao dpng thi t9 le tang tru6ng hien hau g se bi giai han b6i t9 le tang tru6ng to nhien Khi do mac tang truOng thuc se tr6 nen thap hon t9

le tang tru6ng dam bao Ta nhang nghien can nay, dPng tiled bang each nhan manh den tinh phi on dinh da dua ra tru6c day, Harrod rat ra ket luan: nen kinh to se dan dan bi suy thoai do sac cart qua yen

Ngoai ra, Harrod cling dua ra ket luan: lai suat tiet kiem qud cao hoac qua thap ding deu gay anh hung tieu cuc den cOng an viec lam cUa ngithi lao dpng Tiet kiem se tr6 thanh nhan to tich cuc nen t9 le tang tru6ng bao dam thap hon t9 le tang truOng to nhien; nguoc lai tier kiem se tr6 thanh nhan t6 lam suy thodi nen kinh to nen luong tien do tiet kiem qua du thaa so voi kha nang tang trudng dan s6 va kha nang phat tridn cUa khoa hoc cOng nghe

1.4 TANG TRUONG KINH TEVA THol GIAN TAI SAN XUAT TU BAN Cac 19 luau truck day &roc torn lupc thOng qua viec xac Binh hai dai lacing lam co s6 cho mO hinh Harrod - Domar: do la 6 k tang triOng

to nhic")n va 6 4' 3 tang triOng bao chin? Ve mat 19 luan, chung 1a nhang yen t6 lam co so cho m6i lien he giCra tai san xuat to ban va qua trinh tang trueng kinh te ThOng qua viec khai quit hod bang mot s6 nhan t6, nha kinh td hoc Leontieff da dua ra mot mO hinh clpng voi chat nang tao &roc nhieu viec lam trong nhang nam 1960 Nhung thu vi nhat van la each tiep can cUa nha kinh to hoc Von - Neumann vao cuoi nhUng nam 1930 voi tu9ng sat nhap hai nhan t6 to ban va lao dpng thanh nhan to c6 kha nang tai san xuat Sau d6, nha kinh to hoc Brody da nghien cau phat tridn tiep

19 thuyet nay 14 thuyet da ra mot 16i giai thIch ttrong d6i hoan chinh v6 cac giai doan kink nhau cUa qua trinh tang tru6ng nen kinh to dua tren th6i gian tai san xuat cUa cac nhan t6 san xuat

Trong inO hinh da nhan to thupc clang Von - Neumann - Leontieff, tat ca cac nhan to deu c6 kha nang tai san xuat va ky thuat san xuat chi la

tdc nhan phu, tY le, tang trudng t6i da cUa nen kinh to duoc xac dinh theo

Cy le &la lai suat tier kiem va he s6 tu ban duoc sir dung (nhu trong mO

hinh Harrod met loaf hang hod) Khi mot loci hang hoa tit' ban du' dila) thi gia cna no bang khOng va loai hang hoa do se" /along toe dOng den m6i pan he _vac dinh 6 le tang trudng tOi da ci;a nen kinh te: Do vay, tdc d6

tang trudng kinh to se khdc nhau tuY thuec vao mac dau tu rong dugc gibi han chi theo lacing tich luy tu ban luu d6ng (v6n luu d6ng) hoac nguot lai, ddu tu rOng lien quan den tang tu ban c6 dinh (v6n co dinh) va tang von nhan luc (hinh 1.3)

Gia thik rang lai suat tier kiem bang 10% Trong th6i kY tai thik xay dung, v6n c6 dinh va luc luong lao deng ky thuat (nhang lao deng c6 trinh de cao) clang du thaa De tang sac san xuat, ta can phai tich luy to

ban luu deng - von hat dOng (tieu dUng trung gian) Neu lacing du tri to

ban luu deng bang 0,5 Lin sac san xuat hang nam thi \Jai lai suat tik kiem 10% se cho ta mac tang trung kinh to bang 20%:

Hinh 1.3 Tang train-1g va tai san xuat ttr ban

Khi v6n c6 dinh khOng du thaa nua nhung ngu6n nhan lac van con

du thaa (khi san xuat khUng hoang thaa, nen kinh to thu6ng dan den du thaa lao deng, ke ca lao deng có trinh de cao, fir cOng nghiep den nOng nghiep ), ddu tu rang se rot vao von co dinh (tu ban c6 dinh); nhu vay he

se; to ban (v) se tang va c6 gia tri tit 1,5 den 2 Lai suat tik kiem rOng 10% se lam tY le tang trudng dao deng trong khoang ta 5 den 7,5% T6c

do tang trung tuong ang v6i thai kY "skr phdt tri6n dieu kS, cua nen kinh

te' Nesn kinh te thein k.57da duoc biet den v6i cdc nu6c Chau Au va &it

nuoc Mat Tr6i moc - Nhat Ban tir sau dai chitin the gioi lan thir hai, va

On day la cdc nen kinh to "m6i n6i"

Trong mot nen kinh to den giai clop truthig viec tich luy tu ban (tich luy von) khOng chi lien quan den tu ban him hinh (von vat chat)

ma con lien quan den von nhan luc He so tong tu ban tr6 nen lon hon 3, khi dO t6c dO tang tru6ng khOng chi dung 6 mCrc 3%/nam De don gian hod van de, cdch phan tich nay nhan manh den yeu t6 th6i gian tai san xuat cUa cdc thanh phan khdc nhau cau thanh nen von; dieu do khOng nhirng dem lai mot su giai thIch thd vi ye cdc thei kST tai thiet xay dung va

"su troi day dieu kY", ma con dua ra nhimg tier' de quan trong cho cdc quan diem trong hoc thuyet tang tru6ng not sinh

2 CUA TANG TRU'&NG NGUYiN TAC VANG

VA VAN De PHAN CHIA THU NHOP

Nhirng IY luan dm Harrod ve kha nang tang tru6ng dinh ky Xi lam nay sinh hai van de khdc bier, d6i lap voi cdc hoc thuyet kinh to till& do D6 la:

1 TInh on dinh dm tang tru6ng phat sinh bei su tdc d9ng tiling 116 giira s6 nhan va gia t6c;

2 Kha nang dam bao mot xa hei day du cOng an vidc lam, diet.' (16 c6 nghia la tY le: tang tra6ng bao dam can phai du6c can bang hod, ma

tY le nay la ket qua cua khuynh twang tiet kiem, dm he s6 to ban;

va tY re tang tra6ng ter nhien la ket qua cua su tang dan s6 va t6c d9 phat tridn khoa hpc cOng nghe

Van dd thin nhalt ma hpc thuyet chu trinh de cap den la su tang tru6ng theo chu kY Win de dill hai se tr6 thanh van de /Net ye:u cua h9c thuyet tang tru6ng can bang ma chung to se xem xet ngay sau day Phat trien Va0 nira cu6i nhimg nam 1950, hoc thuyet nay nham giai thich dac diem mang tinh chu kY cua qud trinh tang trithng kinh te Dac biet tir sau chien tranh the giai thu 2, do su phat trien khd "ngoan muc" trong giai (loan tai thiet va xay dung lai nen kinh re", nhung cau hOi ma Harrod dua ra ve nhiing nguy co co the cua n6n kinh to chua ducc quan tam dking mac - tham chi chua duoc (16 cap tad

Ngtroc lai, cac khai niem ma Harrod va Domar dua ra nhan manh den su khOng tuong help glib tY le tang tru&ng kinh to (tY le nay la ket qua cua tie't kiem va cua khoa h9c cOng nghe) va tY le tang tru&ng to

nhien (tY le nay phai dam bao day dU viec lam) Neu sir' tang trung kinh

to lam can bang hai tY le nay thi dieu do c6 nghia la nen kinh te linh hoat

lion nen kinh to theo mO hinh Harrod - Domar

Dtra tren nhiIng kien fink cna hoc thuyet sue san xuat bien, hoc thuyet tan c6 dien ye tang tragng cUa Solow, Swan va Tobin da dua ra khai niem ye tinh linh hoat ben canh ky thuat san xuat tilt la tinh linh

hoat cUa he s6 tu ban (he s6 v6n v) Nhu vay, theo quan niem ye tinh linh hoat nay, dieu do chinh la nhang plicin ling qua lai giita gia cd, hong, va loi ich Ccic ninth to nay clang mgt vai tra quan trong trong qua trinh dieu chinh hoc thuyet tan ca' dien (Solow - 1956)

Theo quan niem ve sir chenh lech mire phan ph6i thu nhap, dieu do cling c6 nghia la viec tiep can sau sac vain de cita phai Keynes m6i da

phan tich sir dieu chinh tY swift bdo dam theo ty le tang trugng ter nhien

Trong phan tich cUa Kaldor (1955), viec tich luy tu ban khOng con la ket qua theo khuynh huang khOng doi nham tiet kiem thu nhap; ngugc lai d6

la t6c de tich luy ma no xac dinh lai suat tier kiem theo sir thay d6i chenh lech mire phan ph6i thu nhap Do vay, theo phan tich cUa Keynes, s6 nhan

dau tu la nen tang cua hgc thuyet viec lam trong thoi kS) ngan ban va tinh trang xa h gi Mien (Ong On viec lam; dung thai la nen king cna hoc thuyet phan chic thu nhap trong thoi ky dai han va tinh trgng A-c7 hoi ddy dii tong On viec lam

Do vay, theo hai each tiep can nay, van de xac dinh each phan chia thu nhap da (live dat ra Van de nay da tr6 thanh tieu diem cita nhiing cuec tranh luan giira hai trugng phai tan c6 dien va hau Keynes trong nhilng nam 1950 va 1960 Hai hoc thuyet nay se giai thfch hai clang dac

tit-1h quan trong: d6 la tinh on dinh cfia each thti'c phan chic thu nhap va tinh do dinh cna sit' tang trtOng

2.1 MO HINH TANG TRUCiNG TAN CO DIEN

Khi cac nhan t6 san xuat c6 kha nang thay the thi he s6 tu ban troy thanh ham cUa kh6i lacing tien te (cueng d6 tu ban) Trong theri ky khoa hoc ky thuat kern phat trien, sue san xuat trung binh cUa tu ban (1/v = nghich dao cua he s6 tu ban) va sue san xuat tu ban bien la nhfing ham phi tang trugng kh6i lacing tien te (luang to ban/dau ngugi) Khi tai

suat tiet kiem khOng doi thi tY le tang truOng bdo ddm (sly) cling la mot ham phi tang truOng kh6i lung tien te Do vay, tinh linh hoat cUa ky thuat san xuat cho phep can bang tY le tang truang bdo ddm va 6'i le tang tra&ng tu nhi'en (hinh 2.1) Neu ban dau nen kinh to có mot lacing to ban/dau ngued qua dia) (diC,rn A - hinh 2.3), thi tY le tang truOng bdo ddm - c6 nghia la tY le tang truOng to ban - se cao hon tY le tang tru&ng

sire lao &Ong va luting to ban/dau ngued cling se tang Khi dO nen kinh to

se di chuyen den mac tang tru6ng can bang (diem E) Khi luting to ban/dau ngtrOi ban dau cao hon gia tri can bang thi hien nhien van de, se

di theo chieu huong nguoc lai

k0 k* Kh6i luting tu ban

Luting tu ban/dau ngugi k

Hinh 2.1 MO hinh tang truang tan co din

Nhu nha kinh to hoc Solow da chi ra, each dieu chinh au& day

&roc thuc hien ngni bang each dua tren mac chenh lech A phan chia thu

nhap Khi luting to ban/ dau ngubi qua thap (diem A - hinh 2.1), thi sac san xuat bien to ban - c6 nghia la tY suet lgi nhuan - se cao hun tY suat loi nhuan ling v6i str tang tru6ng can bang COn d cac th6i IcS7 khac, mac tien luting thuc lei qua thap va ky- thuat san xuat tu ban chua phat then day clU Nhung viec tang luting tu ban/dau nguM se lam tang twang sac

lao d6ng va muc Wong thuc d6ng th6i lam giam sac san xuat Bien tu ban (tY suat 10 nhuan) cho den khi nen kinh to dat toi dung tang trudng can bang D6 linh hoat cUa luong cho phep dieu chinh trong su6t khoang th6i gian dai de darn bao mot xa h6i co day dU c6ng an viCc lam Neu mut luong thuc cMig ididc thi tY le tang trtrOng kinh to (tY suat bdo ddm) se cao hon tY le tang sac lao Ong Di6u nay se gay ra sir thie-u tang tru'Ong v'e Inc lacing nhan c6ng Su thieu hut nay tat yeu se keo theo sy tang cao mire luong thuc ma no se di chuyen den dung tang tru6ng can bang moi (diem E - hinh 2.1) Chting ta se xem xet mo hinh phi can bang trong phan sau (m6 hinh nay lien quan den de khOng linh hoat tuong d6i cUa mat tin Wong thkrc)

MO hinh tang trtt6ng tan c6 din :

Ham san xuat v0 nang suat khOng dPi:

(clang nay da dugc trinh bay 6 hinh 2.3)

Goi : ii - tY le tang truOng skit lao Ong;

s - lai suat tiet kiem;

tY le tang truOng tu ban (tY le tang tru6ng v6n - tY suat bao dam) &roc tinh theo cOng

1 dK

1 dk

= S

k dt hay dk

Nguyen tac yang

Trong truOng hop tang truong can bang (k khOng d6i), thi Wong to ban/dau nguoi (lacing von/dau nguOi) va mac tieu thu theo dau ngubi duoc xac dinh theo cOng thCrc sau:

Da'y nhanh tarn thoi ctia tang

de tang tru9ng cUa nen kinh no chi lam thdc day nhat th9i su tang trtthrig 'sari xuat va tang kh6i Wong tu ban nham bat kip theo dubng tang r;.trudng tu ban cao hun, co nghia la du9ng bieu dien lung tu ban (lacmg 'tier] to ban)/dau ngueri tang cao hon (hinh 2.2) Tren dubrig tang truang nay, mac san xuat tinh theo dau nguoi cling se tang len

Ty le tang trugng

s„ s1

Hinh 2.2 Tac Ong cua vi0 tang 07' le tiet kiOn

2.1.2 Nguyen t'ac yang

Trong qua trinh tang truerng deu theo chu ky, lacing dau tu/dau ngueri se tY le theo 1u9ng tu ban/dau ngued: de tang gap dOi lugng tu ban/dau ngueri thi cling can phai tang ggp dOi lacing (Mu tu/dau ngued;

clieu do du9c the hien qua clop thang OC (hinh 2.3), trong d6 (10 d6c cOa duong thang nay bieu dien tY le tang twang cUa nen kinh te Luvng san pham/dau nguei ding tang theo v6i luvng tu ban /dau ngued nhung sac san xuat bien cUa von lai kh6ng tang tru&ng, de &lc cua throng cong OBC

San xuat theo dau nguoi (k)

Do vay se ton tai met du9ng Lich luy; clueing nay keo theo mire tieu thu tei da (finh theo dau nguoi) Mac lieu thu nay dat tad diem A* - diem

ma tai dO sac san xuat bien tu ban (de dee cna clueing tiep tuyen tai diem A) se bang tY le tang traOng dm nen kinh to (de doe cua doan thang OC) Mat khac, (Ming Lich luy keo theo mac tieu thu cao nhat linh theo dau nguoi aing cllinh la tY suet 19i nhuan (hoac tY le lei Ich) hay bang CY le tang trueng DO chInh la nguyen tac yang (ducic thiet lap bOi hai nha kinh

to hoc Phelps va Desrousseaux) Khi tY le tiet kiem thap hurl tY le dm nguyen tac yang (tY suet 1cii nhuan hoac tY le lei Ich cao horn tY le tang

trueng), thi viec tang lei suet tiet kiem se lam tang mac lieu thu theo &du nguOi Con khi tY le tiet kiem cao hun tY le dm nguyen tac yang, thi se xay ra tinh trang lacing tu ban tich luy qua nhieu: viec giam ty 1C tiet kiem

se khuyen khIch tieu dung, cho phep tang mac lieu thu theo dau nguoi

San xuat, dau tu va tieu dung theo

dal] ngugi

0 k k* Luting tu ban theo dau ngubi k

Hinh 2.3 Nguyen tat yang

2.1.3 Nhang tien b§ khoa h9c k9 thuat

De co the mO ta tien trinh cua nen kinh to hien huu, ta can phai tinh den yeu to luoig san plidm binh pan theo ddu ngffoi tang trong mot thOi

- do la d6i tugng cUa nhting tien bp khoa hoc ky thuat De ton tai mot the dp tang tragng can bang theo lai suat tiet kiem khong d6i thi khoa h9c 1ky thuat can phai nam dugc chin khoa clia Harrod, co nghia la khoa hoc ky thuat chi lam tang nang suat lao dpng Trong gia thiet nay, luting to ban binh quan theo dau ngugi, luting san pham binh quan theo dau ngued va mdc lieu thu binh quan theo dau ngued tang theo t6c dp phat tri6n cUa khoa hoc ky thuat Nhu vay, viec phan tich trugc day van co the chinh xac bang cach ta sda doi, dieu chinh lai sac lao dpng phb hop theo nhang tien bp cUa khoa hoc 1(5"/ thuat, có nghia 1a ta do sdc lao dpng bang don vi hieu qua

2.2 LAI SUAT TIET KIN VA CACH PHAN CHIA THU NHAP (KALDOR)

Nhang mO hinh chat luting cua phai sail Keynes va mO hinh phat tri6n ban dau cUa Kaldor da de cap chinh xac hon den mot cach nhin d6i lap voi nhang mO hinh co dieu chinh truoc day Kaldor gia thiet rang khuynh huong tiet kiem tien (khuynh hung tiet kiem to ban) s, cao hon khuynh huang tiet kiem nhan cOng s„, Do do, tS7 le tiet kiem se la mot ham tang tru6ng phan lqi nhu4n cl4t &roc to khOi luting san phtim trong nuot va t5, le tang tru'O'ng bao dam (sly) ciing trd thanh mot ham tang tweing t57 suat loi nhuf.in (hinh 2.4) Do vay, se ton tai mot gia tri cua t57 suat loi nhuan sao cho thOng qua gia tri nay nen kinh to se tang trtro'ng can bang trong mot xa hpi có day dU viec lam (diem E - hinh 2.4)

Mat khac, su can bang nay la on dinh Neu ty suat Igi nhuan cao hon gia tri can bang thi tY le tang truOng bao dam se cao hon tj le tang twang to nhren Neu nen kinh to tang tragng theo t57 le tang traCing bao dam thi se xay ra hien along thieu tang trugng ve nhan cOng lao dpng va

do vay (long luting se co khuynh hung tang len Mtic tang tien luting thuc khi dO se keo theo si suy giarn ve tY suat lqi nhuan, lam su tang trugng tY' le bao dam bi lidm: di chuyen den diem can bang mdfi E

Ty le tang trucking

r r* r, Ty le lqi nhup r

Hinh 2.4 Tang trtrOng va phlin chia thu nhUp trong mo hinh Kaldor

Qua do, to ding co the dua ra nhirng khdi niem ban dau ye hoc thuyet phi can bang cung - cau tren thi twang hang hod Neu khong ton tai mot sty can bang gida cung va cau, thi t57 le tang tru&ng co the ducrc xac dinh giira tY le boo dam va t.57 le to nhien trong kS/ ngdn han (diem A l - hinh 2.4)

• g<g„,: Thing du cung tren thi tru'ong hang hod

• g>g„.: ThOng du cau tren thi treing lao &Ong

Thong du cung tren thi trubng hang hod keo theo sty suy giam ve gid san xuat; thong du cau tren thi tru6ng lao Ong keo theo su tang Wong danh nghia Trong ca hai tru'ing hicrp nay, dieu nit ra la- su tang tin Wong thkrc va sty suy giam tY' suit lqi nhuan se clan den trang thdi can bang Trong treing hcv nguqc 'di, tai di6rn A2, thing du cau tren thi trubng hang hod va thing du' cung tren thi trueng lao long lam tang tji suet lqi nhuan va ding clan d6n di6m can bang E

3 PHAN TICH THEM

VCCACH NAN TAN CO DIN

Nhirng nam 1960 da c6 nhang kr& phdt trien dai ve ly luan va thuc tin d6i v6i mO hinh tan c6 di6n: t6i uu hod cdc the (10 tang truoug, cdc

mO hinh to ban da cap, phan tich cdc nhan t6 tic Ong d6n sir tang trtrong trong kST dai

3.1 TICH LUY T61 T61 LIU XA HOI VA -r6i U'U NHAN

Trong mO hinh tang traong tan c6 dien duqc phat trien vao giira nhirng nam 1950, tS le tiet kiem dupt gid thi6t la khOng d6i (sau nay, Harrod va Domar deu sit dung gia thi6t Keynes nay) VI vay, viec ltra chon tjT le tiet kiem bang bao nhieu la van de gay tranh cai gida cac ca nhan va xa hOi, gifia mire tieu dung hien nay va mitt tieu dung tuong lai Trong qua trinh nghien cdu hoc thuye't hien dai ve tiet kiem, ciic nha kinh

to hoc da dua tren su lua chon mang yeU to vat chat cua cdc 110 dan cu (dac biet 1a d6i v6i hoc thuy6t ve chu kS/ song cua Modigliani); nhirng mO hinh tich 1uy t6i uu se dua.ra nhting cach thdc lua chon nay

Trong qua trinh phat trien hoc thuyet, nha kinh to hoc Ramsey (1980) da c6 cOng lao to Ion vai 16i giai thich quan trong mang tinh thuc nghiem o Philp bang viec xac dinh tji suit hien dai hod theo chuong trinh tang trueng kinh te" Ngoai ra, 1T thuya nay ci:ing dan thin duqc thay the b6i hoc thuye't t5, le tier kiem ngoai sinh va thi6t lap mot m6i truCing quen thuOc mod cUa cac hoc thuye't tang tru&ng not sinh

3.1.1 Tang traCing t6i au va nguyen tac yang du'oc di6u chinh

Win de gay tranh cai gilla mire tieu dung hien tai va mdc tieu clang tuung lai co the duqc torn luqc bang hai tham s6:

• Thu nhat: lqi ich tirc thi cUa tieu dUng

• Thd hai: lgi ich tdc thed nay duqc hien tai hod theo mot ty suat nhat dinh trong ham lqi ich c6 yeu to thi gian, c6 nghia la ty suat hien tai hod la t.57 trong arcing d6i cUa lqi Ich hien tai va tuong lai

T57 suat nay duqc ky hieu 0- la 67' suat uu dai hien tai

Trong giai doan tang truCing can bang, t.57 le tie-t kiem kh6ng dOi va

to c6 ham uu dai tai thai diem hien tai Khi xa hOi ton tai mot nguyen tac dun gian (nguyen tac Ramsey hoac nguyen the yang duqc dieu chinh) lam eau not giira sue san xuat tu ban bien \Tali t57 le tang trueng cira nen kinh to thi sue san xuat tu ban bien se bang t57 le tang truong (ma tY le nay tang theo ty suat uu dai hien tai)

3.1.2 T6i u'u x5 h§i va t6i au to Wan

MOt van d6 quan trong khac cua mO hinh tan c6 didn 1a tit-1h tuung throng giira t6i uu xa hOi va sir can bang c6 canh tranh Neu cdc 110 dan cu xdc dinh mire phan chia tieu thu - tiet kiem cua ho bang each t6i da hod lgi ich vat chat trong dieu kien han the v6 ngan quy7 thi tS,' le sinh led ar tai san tai chinh cua cac 110 dan Cu nay (tY suat lqi Ich r) trong truemg hqp tang tru6ng can bang se bang tong hai dai luong: qi le tang tru6ng va t5/ suat uu dai hien tai:

Mat khdc, viec t6i da hod lgi nhuan trong cac doanh nghiep duoi diet' kien co ham san xuat se dan den six bang nhau gitia sue san xuat to ban bien va ty suat lqi ich:

dgu ngu'di

(3.5)

Do vay, sir can bang mang tinh canh tranh se den den viec t6i tru xa hei c6 dac tinh du is bieu dien qua bieu thirc can bang (3.1)

Tich luy toi uu va nguyen tac Ramsey

V6i cdc cid lieu da cho 6 phAn truck, ta c6 mdc can bang cna thi tru6ng hang hod ductc bieu dien nhu sau:

Cung lao Ong N, (bang cdu lao deng) tang theo tY le n Bang each

sir dung cdc bi"en binh quan theo ddu ngu6i, m6i quan he tren c6 the ducfc viet thanh:

Bien a lung ddu to binh quan theo ddu ngkr6i bao gom hai s6

hang: ddu to gia tang nk, va dau to lam tang lacing von (1u6ng ta ban)

dkl dt

Dung tich lu -y t6i uu dat dude beri he plurong trinh sau:

m ax fu(c)e °rdt;u'> 0 ,u" < 0

0

fi t' f(k,)=c,++ nk,

Dao ham bac nhat, ta suy ra dieu kien Ramsey

c = c,k = k, dc di, = 0 {(5)./ 1 (0= n +

(6)c = f (k) — nk

Lacing du trir lien to tu ban k trong trueng hop tV' sugt uu dai hien

tai 61 > 0 se nhO hon Wong dir trir tien to to ban k tuong ung voi nguyen tac yang (k* khif'(V) = n) Khi 1/8 khOng dei (ham s6 c6 de co dan thay

the c6 yeu to thi gian khOng dei) thi nguyen tac Ramsey tr6 thanh:

Khi de co dan thay the bang met don vi (u=log(c,)), thi sdc san xua:t

to ban bien bang t/ le tang trudng (n+y) (6% le nay dtroc tang theo ty suat

uu dai hien tai)

3.1.3 SI! ua thich thai di6'm hien tai va kta ch9n clueing tang tru'ang

Ua thich la met khai niem daec dung lan dau bei cac nha kinh to

hoc tan c6 dien sau do duec dung kha ph6 bien trong cac tai lieu kinh t6 hoc hien dai Day la met khai niem thuec pham trY tam l5T, rat MI6 do dac

va Wong hoa, tuy nhien lai rat tien 19i cho cOng tac nghien dm

Trong thuc t6, cac chu the tham gia thi tnthng (ngtred tieu dung, cac

t6 chic hay doanh nghiep ) c6 xu huong quan tam 'Mien den hien tai

Nhu vay, khi cac nhan to c6 sit u'a thich th6i diem hien tai, thi throng Lich luY Cei uu ttrong dng voi khei 'Yong tu ban (khei luting tien tO, tj, le ti6t kiem va mac tieu dung binh quan lien &du ngtrei se th4 hon so voi dveng "nguyen tac yang" Khi suc san xugt tu ban bien cao hon ty le tang tra&ng, thi viec tang 'di swat tiet kiem o ky dai han se lam tang mire tieu the binh quan tren dau ngt.r6i Tuy nhien, qua hinh 3.1 to nhan thay rang 6 kST ngiin han, yiec giam mac tieu the binh quan theo dau ngubi limit khi c6 skr thtic day tam th6i sir tang tru6ng san xuai se dtm den mac lieu dung binh quan lien dau ngtreci ti6p tvc tang cao ho'n nira

(3.8)

(3.9)

Neu tY trong cdc mac tieu dung along lai la dOng nhat trong ham 19i ich co yeu t6 tiled gian (0 = 0), thi cdc tdc nhan se luen thick dung tich Iuy Dugng nay &tin den mdc tieu dung binh quan tren dau ngugi cao nhk (nguyen tac yang) neu lugng tieu dung tam th6i bi mat di thi

no lai dugc bit dap lai bgi lgi nhuan tir tieu dUng tuong lai Nhu vay, gia tri B ket hgp voi du'gng tang trugng la tY suet hien tai hod Ty suet nay lam can bang gid tri dugc hien tai hod ciia viec mat di lugng tieu dung ngin han va lgi felt dugc hien tai hod cita lugng tieu diing tuung lai

Tieu Stag theo dau ngtrgi

• Nguyen tac yang Tieu dung t6i da r =

Hinh 3.1 Tich luy t6i uu 3.2 PHAN TICH CAC NHAN TO TANG TIRtioNG

Gia sir c6 met ham san xuCit vai cdc nhan t6 co the thay the dugc Ghi thie't nay dugc xem xet kyi tren co so phan tich sir tang trugng tuy thuec vao rink de (long gop cita timg nhan to san xuk

Nat cdc nang suet guy me ding bang met don vi, va cdc nhan t6 san mak dugc tra luting theo sac san xuk bien thi tY le tang trugng san xugt la tong cdc deng gop cUa tirng nhan to, dugc xric dinh theo phan tra tin luting c6a tong nhan to san xuk

• Neu to ky hieu a - phan Igi nhuan;

(1 - a) - chi phi lao Ong;

g - ty le tang tru6ng san xuat;

k - tS7' le tang tru6ng tu ban;

14 tra6c day - th6i kY xay ra khUng hoang ddu lira - hic do sac san xuat

va kh6i Wong ta ban ding tang voi toc dp hang nam la 5%, va s6 lacing lao dpng tang voi tY le 1%, voi he s6 a = 0,3 thi phdn clang g6p cua kh6i

1u6ng tu ban d6i voi t6c dp tang truOng la 1,5%, cUa s6 luong lao dpng la 0,7 va cUa thanh phan ytir 2,8% den 5%

Sau d6, van de nay da duoc nha kinh to hoc Denison tiep tuc nghien cuu Ong dd di sau phan tich bang cach phan biet CO rang cac mac do khac nhau cUa cOng viec tuY thupc vao chat 1u6ng cOng viec (viec tra luong cho cac cong viec nay dirgc de xuat tra theo sac lao dpng bien tuong (mg); dOng th6i co tinh den hau qua cUa viec huy dpng cac nhan to Khi do, thanh phan y co the se bi giam di (vi du: nghien cau cUa Carre,

Dubois, va Malinvaud d6i voi nu6c Phap)

3.3 MO HINH VON DA CAP (MO HINH Tli BAN DA CAP)

Trong mO hinh tan c6 dien co ban ton tai mot sty phan chia ro rang hai nhan to: su tich luy tu ban va viec ap dung cac lien bp khoa hoc cOng nghe DO la nhuoc diem lon cUa mO hinh tan c6 dien ma cac mO hinh tu ban da cap dang c6 gang khdc phuc Cac m6 hinh nay gia thiet rang, cac trang thiet bi hien nay deu hien dai hon cac trang thiet bi tru6c kia Do vay, viec thay the cac trang thiet bi cu c6 cOng suat thap bang cac trang thiet bi moi có cong suat 16n se dan den viec tang nang suat lao dpng cho nen kinh te Nhu vay su tien bp khoa hoc cOng nghe van 1a nhan t6 ngoai sinh nhung dong th6i lai la nhan to vO hinh d6i voi cac trang thie't bi mai;

con viec ap dung nhung den bQ khoa hoc ky thuat se trd thanh nhan t6 nOi sinh theo chieu haong tee do qua trinh tich luy to ban nhanh hurt hoac cham di

Tiep sau dO, cac nha kinh to hoc Solow, Tobin, Von Weisacker va Yaari [1966] da tiep tuc nghien cau mot each town dien hurl va dat van de nay vao trong gia thiet: ky thuat san xuat la co dinh (khOng thay d6i) vao thOi diem ltra chon day to va trong suet chu ky song ciia may moc thiet bi (co nghia la khOng co su tien bQ vd khoa hoc cOng nghe trong died ky nay- mO hinh nay co ten goi la clay - clay) Dac biet h9 da minh chung dirpc rang clang mO hinh nay vdi he s6 c6 dinh nhung nhung tien b0 khoa hoc cOng nghe dapc sat nhap vdi khi lacing to ban (vCin) thi dieu d6 cho phep chting ta tim thily lai tat ca cac ket qua cita mO hinh tan c6 dien vdi cac nhan t6 co the thay the duck Viec thay the to ban (v6n) - lao Ong khong con la ket qua ciia gia thiet It hien thuc cita mot lugng to ban dong nhk va de thay the ma la ket qua dm gia thiet thay the cac thiet bi cu bang nhung thiet bi mdi

Du trix ta ban se du6c dimg de mua sam cac trang thiet bi vdi cac the he khac nhau nhu cOng suat cua trang thiet bi may moc doi moi nhk tang vdi ty le khOng cl6i trong suet tiled gian sir dung (nhung tien bQ khoa hoc cOng nghe se sat nhap vdi to ban lam cho nang suat lao d(ing duvc cai thien) Ta có the bieu dien cc( ckt von tai mot thi diem cho trudc trong bieu de, Solow (hinh 3.2a) M6i mot the he may moc dugc bieu dien b6i mot hinh Chit nhat: chieu ngang cua hinh chi' nhat bieu dien cOng viec can thiet phai dugc thuc hien, con chieu cao the hien nang suat lao clOng c6 six dung may moc Dien tich cita mot hinh chir nhat the hien viec san xuat dupe thuc hien co su trp gitip cua cac may moc thiet bi Neu

ta bieu dien toan 60 cac may moc thiet bi tit cloi c6 nhgt den cac dOi mdi nhilt thi ta se co mot hinh chu nhat ma chieu rOng the hien su suy giam t6c do khoa hoc cOng nghe, con chieu dai the hien viec san xuat dugc thuc hien vdi town bQ cac thiet bi san c6

Trong giai clop tang trung can bang, khi chu ky song cua thiet bi khOng d6i thi sirc san xuat trung binh tang theo t6c do phat tridn khoa hoc cOng nghe Sue san xuat trung binh nay se ngay cang tiep can den gin sue san xuat 16n nhat (c6 nghia 1a nang suat cua cac trang thiet bi dad mdi)

Giam th6i gian song

ma chu ky song cUa cac may moc ngan ngUi Viec nit ngdn yang dad da cac trang thief bi may moc cho phep tang tam tiled nang suat lao Ong trung binh (hinh 3.2b), nhung clOng thei lai dei hOi mot lai suat tie't kiem cao hon: thuc vdy, viec dau to thay the se cao hon so v6i Ong ded ngdn ngUi cUa cac thi6t bi, may moc Trong clang mO hinh nay, yang dai cUa cac may moc thief bi cling (long mot vai tro quan trong nhu vai trO cUa Wong tin to to ban trong mO hinh tan c6

Nang suat lao Ong Nang suat lao-d(mg

Cong suat cUa cac thief bi mot

Cong suat trung binh

Luang thuc

Vic lam Th6i gian

Hinh 3.2 MO hinh ttr ban da cap

a) Tai th6i diem t; b) Qua trInh tie'n tridn cua nang ltrc san xuat

Nhu trong mO hinh tan c6 di6n, khi cac doanh nghiep t6i da hod lei nhuan, h9 se sir dung tat ca cac ngu6n ltrc ye may moc thie't 111 (16 nang suat lao dOng can phai cao hon auk Wong thuc phai tra (hinh 3.2a) Nang suat lao Ong bien bang s6 Wong thuc phai tra Ta ding nhan thay rang tS, suat 19i nhuan bang nang suat to ban rung bier' CuOi ding, v6i tinh hu6ng vd nen kinh to tang truCfng cho truoc, v* tang lai suat fief ki4n se lam tang s6 lacing san pham binh quan dau nguoi bang cach rut ngan yang d6i cua cac may moc thief bi; di6u do clOng thoi cling lam tang mtic tieu dung binh quan tren dau nguei cho du ty suat lqi nhudn c6 cao hen tY

le tang truen$ (nguyen tdc yang)

4 TANG TRUING PHI CAN BANG

Hoc thuye't tang traeing khOng hoan town bier? mat trong nhang nam thang xay ra cac cu9c khUng hoang kinh te" Trong suet qua trinh xem xet lai hoc thuye't Keynes vai the d9 tang truOng can bang phi Walrasien (Benassy [1976], Malinvaud [1977], rat nhieu cOng viec nghien cdu da duoc phdt trien, (lac biet la d nuoc Phdp, de nghien cdu cac the dO tang tru6ng ma trong dO su cling nhac cOa gia ca va tien luong da dan (ten mgt thdi d9 bi quan d6i vc5i nen tang trudng phi can bang Cac mO hinh tang twang nay mang hai sac thai: ban chat phi can bang (thi trueng hang hod

va thi truing lao d9ng) va dang d9ng thai cluoc nghien cdu (d9ng thai cOa cldu tu va d9ng thai cOa gia ca hoac d9ng thai cOa tien luong Mot each tang quat, cac mO hinh dOng phi can bang nay dan den cac the cla mang hai dac tinh: thd nhat la ban chat phi can bang ngan han (that nghiep theo thuyet Keynes, that nghiep ca dien, lam phat tiem va thd hai la clang thai cOa gia ca hoc cOa tich luy to ban

De don gian, chting to han che- nghien cdu chi trong ba linh vuc sau:

• Dang thai cOa tien luong trong mO hinh tang tru6ng tan ca dien vii tinh phi can bang cOa thi truing lao dOng

• Deng thai cOa ddu tu trong m6 hinh Harrod - Domar vii gia c6 dinh

Ta nhac lai: h9c thuyCA tang truOng can hang phi Walrasicn phan biC;t thanh bu clang chInh: that nghiOp Keynes then mot direng cat' khOng day du, that nglii0 co di6n then mot mac tien lacing thtrc qua can va lam phut ti6m an (hoac mot xi) hOi da Mira vi4 lam) ma h do, viOc sun xuat bi han the bOi cung lao clOng cua nhiing ngithi lam cOng an lucmg

• Ddu to va loci nhuan

4.1 TINH PHI CAN BANG CUA THI TRUONG LAO ONG VA TIEN LUONG: Sti TAI HO MO HiNH TAN CO DIEN

Trong mO hinh tang truang tan c6 dien, khi lung tu ban tinh theo ddu ngt.r6i khzic voi gia tri ma gia tri nay dieu chinh tY le tang tru6ng bao dam va ty le tang tru'Ong tu nhien), thi no se clan clan to di6u chinh den gid tri can bang thOng qua tich luy tu ban Nhu chung to cla chi ra, viec dieu chinh nay gia thie't bao ham mot su Nen thien A cUa auk phan phoi thu nhap, c6 nghia la tinh linh dOng cila muc luong thuc tra se dap Ling tut thi

su tien tri6n tu'o'ng Ling cUa nang suit lao Ong Trong qud trinh dieu chinh, n6n kinh to van clay dp viec lam, viec thay the tdc nhan tu ban bai tdc nhan lao Ong cho phep thu6ng xuyen dieu chinh s6 lugng viec lam theo lacing dan s6 trong do tu6i lao Ong hien c6 Ngtroc lai, mO hinh Ito [1980] dim ra tinh tong nhdc trong viec dieu chinh attic Wong thyt Thi tru6ng hang hod van luOn luOn can bang (dau to duoc xac dinh b6i ti& kiem, do vay cau luOn Ong nhdt voi cung hang hod); nguoc lai, do tinh cung nhdc cUa mac luong thuc w, thi truOng lao dQng c6 kha nang xay ra

su mat can bang

Thyt vay, theo gia tri ban dau dm mat do tu ban (lacing vein hay lacing to ban tIng voi tong so dan trong c10 tu6i lao dOng hien c6 hieu

la k) va cua mac Wong thuc tra, nen kinh to c6 the duoc bie't den theo ba cite dO sau:

• Che de thdt nghiep c6 dien

• Che do du thira viec lam

• Che dO xa hOi dU cong an viec lam

Nen kinh to se day dU cOng an viec lam khi mat luung thin w duoc di6u chinh theo gia tri tu ban tren dfiu ngubi Di61.1 nay cho phep bao ham tong cung lao d6ng: claCcng cong k (o) trong hinh 4.1 Dung cong nay se tang tru'O'ng ne'u mdc lung thuc tang thi can phai thay the tac nhan tu ban b6i tdc nhan lao Ong, do vay se lam tang khoi luong tien to tu ban nham dam bac, mot xa hOi day dU cOng an viec lam Khi mac lung thuc tang len cao horn so voi gia tri tai au nay thi dung cau lao Ong cUa cac doanh

co*

B

Tien luong thuc to co

Dieing cong cldy du viec lam

k k( co)

nghiep se tra nen qua yeu va )(ay ra hien tuong that nghiep (that nghiep c6 dien bii vi tien lacing thuc to phai tra qua cao) Nguoc lai, neu mac luong thuc thap hon gia tri t6i au nay thi doing cau lao Ong cila cac doanh nghiep se cao hon dung cung lao Ong va nen kinh to 6 trong tinh irking du thira viec lam

Viii mot t5/ le tiet ki'em cho truic, se ton tai mot gia tri t6i au ma tai

do Wing tier' to tu ban dam bao cho mot qua trinh tang truing can bang

Do la gia tri t6i uu kh6i luong tu ban k* Gia tri nay se lam 6'7 le tang truing to nhien can bang viii t5T le tang truing bao dam De' su tang truing can bang nay ang viii mot xa hOi day du viec lam thi mac luong thuc w* can phai duoc dieu chinh theo kh6i luong to ban k* tren cluing cong dU viec lam (diem E trong hinh 4.1)

Lugng to ban theo clau ngtred k

Hinh 4.1 Ba the dO va su tien trien ctia nen kinh to

Ding thai cUa tien lacing thuc to rat don gian: no hoan toan 6n Binh trong met xa hOi du viec lam, no se giarn trong met xa hOi cc') hien Wong that nghiep c6 didn va se tang trong mot xa hOi du thira viec lam (theo

mid ten hinh 4.1) Nguoc lai, dOng thai cua viec tich luy tu ban phirc tap hon rat nhieu Trong mat xd hai du viec lam hoac du thira viec lam, thi s6

luong viec lam se bi han the bed cung lao dOng va tang twang tu ban phu

thuOc duy nhat vao gia tri ban &du cUa lugng tu ban tren dau ngued (hinh 4.2a) Neu luong tu ban tren dau ngued cao hon gia tri k*(tuong ung \Jai

tang truang can bang theo tY le tier kiem s cho tru6c), thi Wong tu ban se

tang voi t6c do cham hon so voi cung lao Ong va nhu vay kh6i luong tu

ban se giam Nguoc lai no se tang neu k nh6 hon gia tri k*

Trong the dO that nghiep c6 dien, s6 luong tong viec it hon cung lao dOng va tIch luy" tu ban phu thuOc kh6ng chi vao kh6i lacing tu ban dang sir dung k ma con phu thuOc vao kh6i lugng tu ban tai uu dugc ket

hgp voi mdc luong thuc tra k( w) Do vay, tY le tang twang tu ban la mot

ham phi tang truang cUa tien luong thuc duoc tra (hinh 4.2b)

Ty Ie tang twang Ty Ie tang twang

Tji le tang tru&ng tu ban Tji le tang truCcng tu ban

k* Luang tu ban theo dAu nguai Tien luting thtrc to w

Hinh 4.2 Tinh chit dOng ciia loon Wen to tir bin

theo din ngttoi

a) X5 hOi du viec lam hoac du thira viec lam; b) That nghiep

Nen kink to o ky dai han luOn co khuynh huang twang tai su tang twang can bang du viec lam (diem E tren hinh 4.2) Nhung nhu to da chi

ra hinh 4.1, qua trinh dieu chinh se luOn tkr san sinh voi nhimg d6i thay cua the (10 kinh to khdc nhau

4.2 MO HINH KEYNES PHI CAN BANG

Trong mO hinh trubc, dau to luOn bang tiet kiem va thi trubng hang hod bao gib cling can bang Ngubc lai, cdc m6 hinh phi can bang khac c6 tinh den dOng thbi su phi can bang thi trubng hang hod va thi trubng lao

&Ong, va vai tr6 cua viec tich 1uy tu ban trong qud trinh lam mg di sir phi can bang nay Dac biet trong mo hinh duic phat tridn beri Picard [1982], Autume[1982][1988], Muel va Sterdyniak [1979] ham dau to (ham nay

du cc mo phOng theo ham lao Ong cua Malinvaud [1979]) phu thuOc vao kha nang c6 loi nhuan va su phi can bang giira san xuat va nang lire san xuat O day chUng to han the van de can nghien ctiu theo hai nhan t6 bang viec trinh bay lai cdc clang phan tich cua Harrod va Domar trong mO hinh tang truong phi can bang Ta gia thiet rang ky thug san xuat 1a nhan t6 phu va dung cau tu chu tang theo ding mot tY 14' voi cung lao Ong &

ky dai han Dau tu phu thuOc vao su tang trubrig dm nen kinh to va phu thuOc vao su phi can bang giira san xuat hien c6 va nang luc san xuat Cau to chit a,

That nghi'ep Keynes

k* Luting tu ban theo dam nguesi k,

Hinh 4.3a Cac ch6 do tang trtr&ng kinh t6 va tinh ch6t Ong:

trtrimg hip gia co dinh

B

Tai mQt thi diem cho truck, ban chit phi can bang phu thuQc vao cau tu chU tinh theo dau ngir6i va phu thuOc vac) luong du trt tu ban tinh theo dau ngir6i (hinh 4.3a, b) Khi dung eau tu chn va nang luc san xuat cao hon mac san xuat trong mQt xa hOi dU viec lam thi nen kinh to se có nguy coo trong tinh trang lam phat (hoac du thira viec lam) Khi du air tu ban qua thap, nang luc san xuat mQt Fan nira lai thap hon cau va thap hon mire san xuat trong mot xa hQi du viec lam thi nen kinh to se trong tinh trang that nghiep c6 dien Khi cau to chu qua yeu du6ng cau se han the san xuat va xay ra tinh trang that nghiep —> dan den du thira nang luc san xuat (that nghiep Keynes)

Su tin tri6n dOng dugc trinh bay o hinh 4.3a Trong tinh trang that nghiep Keynes, nang luc san xuat qua du thira, dau tu tang cham hon so voi cau va luong du trir tu' ban tinh theo dau ngueti se giam Nen kinh to cang se trong tinh trang lam phat tiem an khi nang luc san xuat cao hon sire san xuat (dng voi xa hOi du viec lam) Trong tinh hu6ng that nghiep c6 dien, nang luc san xuat khOng du, dau to va du trir tu ban se tang Ntur vay, nen kinh to se huOng t6i dung ranh gi6i giira that nghiep c6 dien va

du thira viec lam neu clueing cau tu chu cao hurl duerng eau tu chi' can bang (a> a*) hoac hung toi duerng ranh gi6i giita that nghiep c6 then va that nghiep Keynes neu du6ng cau tu chi' qua thap (a<a*)

Nhu vay to nhan thay rang, luOn ton tai hai tinh trang that nghiep: thd nhat, that nghiep c6 dien "thuan tug" ma tai do, &ILI tu phu thuQc vao sir phi can bang glib mire san xuat trong mQt xa hQi dU viec lam va nang lye san xuat; thir hai, that nghiep hon Op ma tai do dau tu phu thuQc vao sir phi can bang girra duerng cau va nang luc san xuat Trong throng hop dau tien, mot su mO phOng ye du6ng cau da khOng tao duoc bat ca mot tac dOng nao den mac san xuat o kS7 ngan han ciing nhu & 14 dai Trong truerng hop tha hai, mQt chInh sach mO phOng clueing cau lam tang dau tu va nang luc san xuat along lai; dieu do lam tang sac san xuat trong cac kS7 sau

Lam phat hoac

du thira viec lam

C

4 ri

A

a

That nghiep Keynes (K)

0 k* Lacing to ban theo dau ngueri k,

Hinh 4.3b Cdc ch6 do tang trifling kinh to va tinh chat clOng:

&Wing hip gia la mot ham phi can bang

MO hinh tang truOng Mr& day gia thi'et gia ca va mut Wong luOn

claw Wick (khOng linh ho4t) Cau la mot ham phi tang twang cua gia ca

Neu gid cling phu thuOc vao sty phi can bang glib cung va eau hang hod

thi gia se tang (cau to chU giam) trong tinh trang xa hOi xay ra lam phat

tiern an va nan that nghiep (that nghiep c6 dien hay that nghiep hon hap);

con gid se giarn (cau to chit tang) trong tinh trang xa hOi xay ra nan that

nghiep Keynes DOng thai tuang Ong duVc bieu din trong hInh 4.3b Su

phi can bAng cUa thi truerng hang hod luOn luOn bi mat di (theo tang Lan

diet' chinh gia va luong tier' to to ban) va nen kinh t6 hoac huOng tai can

bang Walrasi hoac hung toi Bien ranh gidd giCra dWmg that nghiep hon

hop va duOng that nghiep Keynes (duOng thAng OW)

4.3 DAU TI.1 VA KHA NANG SINH LQI

Khi to xem xet mdc dO anh huong dm led nhuan den ye/u to dau to

(Malinvaud [1980]), thi Ong thai troy nen phirc tap han bed vi no phai t6

hop cdc tdc Ong dm clang he s6 tang t6c nhu trong vi du trate va dOng

That nghiep 2 Lam phat

A

thai cua mac tien luong thtrc nhan (xem vi du Laussel[1982],

Autume[1988], Muet va Sterdyniak[1988]) Dd hidu ro sit tac dOng cUa

loi nhuan, ta se sir dung clang mo hinh track ma trong mO hinh nay cac

nhan 16 san xua 1a cac nhan t6 pity, bang each gia thiet rang milt dau to

hien nay phu thuOc vao sty chenh lech gicra tY le lqi nhuan hien co va tY

suCit lqi felt' Ty le lqi nhuan hien c6 la ket qua led nhuan thuan tuY thu

duqc (tY le lqi nhuan tuong ang voi viec six dung c6 hieu qua hay khOng

nang luc san xuSt) theo tY le sir dung nang luc san xuat MOt tY le lqi

nhuan thSp c6 thd se gay thiet hai den gia tri loi nhuan thu duoc (mac

luong thtrc tra qua cao), hoac cau se khOng tuong ang (nh6 hon) vOi nang

ltrc san xugt Gia thiet rang cau to chit tinh theo &du ngtr6i la khOng d6i;

do do khi dau tu rang bang khOng ta c6 nen kink to hang den trang thai

can bang Walrasi

Tien luong thuc te"

4

That ngh ep 1

0)*

That nghiep Keynes

Hinh 4.4 Dong thai ciia 10 nhuan va 4:16u to

kY ngan han, nang luc san xugt ma dugc an Binh theo Wong du

trir to ban va loi nhuan thi chi gay anh hueng den cau theo haong dau to

(ngtrqc lai, lqi nhuan va dau tu gay anh huong den nang lye san xugt tai

2 Chimg ta da xem xet hinh ye va mO hinh tuong dug thong qua inO hinh dm Antoine

d'Autume

cac ky tuing lai) Hinh 4.4 trinh bay ba the d6 trong bieu clO: truc hohnh bieu dien lugng den te tu ban (tinh theo cldu nguii) k; con truc tung Neu dien s6 Wong thuc tra co Nen kinh to se tien den trang thai can bang Walras khi nang luc san xuat bang sac san xuat trong mot xa h6i du viec lam (k=k*) va khi lqi nhudn (vii s6 luting thuc w) tuong drig vo'i cluing cau (cau bang sac san xuat trong mot xa hgi du viec lam) a) =a)* va &hi ttc rang bcing khOng Khi lqi nhudn qua thap (luong thuc cao hart w*), &hi

tu rang se am Nhu vdy neu nang luc san xuat qua du thira thi )(ay ra nan that nghiep Keynes, có nghia la lugng du tiff tu ban tang len hoac se xay

ra nan that nghiep c6 dien nen nang hxc san xuat van con qua yeu so voi mac cau

Khi lqi nhudn ion (mix Krung thuc te thap hon a)*), cldu to cluing va xay ra hien tugng du thira cau tren thi truing hang hod Nen kinh te trong tinh trang lam phat tiem an neu nang lye san xuat qua du thira (k>k*)

hodc xay ra hien tirgrig that nghiep c6 (lien neu nang luc san xuat khOng dap dug dugc sire san xuat trong xa hgi có du viec lam (k<k*) Ding thai cUa tien te to ban se to suy giam; con ding thai cua Wang thuc tra phu thugc vac) skr mat can bang cUa thi truing lao ding: thi truing nay se tang trong tinh trang có lam phat tiem /an va giam khi có nan that nghiep (that nghiep c6 dien hay that nghiep Keynes) Nhu vdy ta nhdn thay rang ton tai hai vimg that nghiep c6 dien Trong \fling 1, lqi nhudn thap, &du to ring am mac du nang luc san xuat khOng dap Ong dirqc cau va khOng dap dug dugc dU viec lam; con trong viing 2, lqi nhudn cao, dau tu rang cluing va lugng tien to tu ban tang

Neu nen kinh to ban cldu dang tic trong tinh trang co nan that nghiep Keynes vai lqi nhudn dem lai yell (diem M trong hinh 4.4), ddu tu rang se

am vi gia tri lqi nhudn bi mat va nang luc san xuat bi giam (k giam) Theo thii gian, vi giam nang luc san xuat nen nen kinh to deu trai phai qua tinh trang co nail that nghiep c6 dien Nhung viec giam luting se thin ddn tai thiet lap lai mac lqi nhudn va khi w tr& nen nho hon co*, ddu tu ring troy thanh dugng (that nghiep c6 dien 2) Do do ta nit ra ket ludn la, viec tang cau va tang nang lure san xuat se lam cho nen kinh to xuat hien lam phat tiem an; v* tang Wang va tang tien to to ban se lam cho nen kinh te

huang tai trang thai can bang thi trubng lao Ong voi mdc thang du dm cung hang hod (throng bien gi6i WA)

Cac vi du tren day da phan anh throc su tac Ong dm Ong thai ve gia, luong va tich luy tu ban trong mO hinh tang tru&ng ma 6 do su dieu chinh ve gia va luong duoc thuc hien mot cach kh6ng dang Tinh phirc tap cUa chung chinh la phan ion cac m6 hinh thuc nghiem deu bi han the bai viec c6 tinh den tac Ong cila sir phi can bang tren Ong thai cUa gia, luong va tich luy tu ban ma khOng ney ra cac the dO kinh to arcing img Thtrc tien vi mO luOn k6t hop cac tinh hung ma trong do, mot s6 thanh phan luOn doi lap vai nang luc san xtkit cua chUng; con mot só thanh phan khac lai d6i lap \Jai throng cau hoac vai duong cung lao dOng, bCri vi con duOng di to the dO nay den ch6 do khac cc-) tinh lien tyc cna m6 hinh tang truang phi can bang (xem tren diem Lambert [1988])

5 TANG TRU'oNG NOI SINN

VA TANG TRUING NG0131 SINN

Sau mot thai ky dai trang thai ngti at'a auk", (lac biet la vao cuCii nhung nam 1980, nhfing hoc thuyet tang twang da biet den mot su d6i mai sau sac vai sty xuat hien dm nhung hpc thuy& tang trtrong nOi

sink Sir d6i mai nay có ding nguon g6c va có ding nhiing tac dpng nhu

sty d6i mai trong nghien ctiu hoc thuy& kinh te vao cu6i nhirng nam 1970, hpc thuy& thtrong mai quac te: viec ap dung nhirng hoc thuy& nang suat tang twang va hoc thuy& canh tranh khong hoan hao dtroc bat nguon tir nghien cdu nen kinh to cOng nghi'ep dan den mot nhanh khac cua hoc thuy& kinh t6 vi mO De nghien Cif1.1 day du cac mo hinh tang twang not sinh, ta can phai tinh den hanh vi ngtroi tieu dung dtrai clang It so vai gia thiet tY le ti& kiem khOng dai ma chting ta se nghien ctiu trong mac cu6i ding cUa chuong nay NOi chung, xuat phat tir mO hinh cUa Solow va qua qua trinh nghien ciru cac lY do dan den dac tinh khOng the ton tai cua mot nen kinh te tang twang cita lung san phdm theo dau nguai, ta có the lam r6 rang va don gian van de: vai dieu kien nao thi skr tich lay tu ban có the

sdn sinh ra mot sty tang truang not sinh

Ve mat ban chit, do la gia thiet phi tang twang nang sulk tu ban tich lug; gia thiet nay da ngan can qua trinh tang truCing theo mO hinh Solow Gia thiet nay chU yeu nham vao su ton tai cita mot qua trinh can bang mang tinh canh tranh (la phan b6 sung vao gia thiet nang suat quy

mO khOng tang twang) dan den sty au tier' ma chting ta da de cap den tir truac: khi Wang tu ban tinh theo dau ngtrai khOng phi' hap vai duang tuong Crng vai tY le tang twang ttr nhien thi viec tich 1uy hoac viec bO tich lug rang to ban se keo nen kinh te di tren dung tang truOng Khi do, su

tang truOng s6 hieing san pham tinh theo dau nguefi chi c6 the la ket qua

dr met nhan t6 ngoai sinh: su phat trien khoa hoc cong nghe Cho dU no la nhan to v6 hinh theo yen nhang nhan to nay kh6ng lam thay dei su uu tien kST dai han va dac tinh ngoai sinh caa su tang tru6ng Chung ta bat dau di sau nghien cau ye hoc thuyet tang trithrig not sinh bang viec tom tat va nhac lai nhfing he qua va nhting han the cUa mO hinh tan c6 dien

5.1 NHCING HE QUA VA HAN CHE CUA MO HINH TAN CO DIEN

ChUng ta da de cap den hai van de gay tranh cai nhat trong hoc thuyet tan c6 dien ye su tang tracing:

• Nen kinh te" chi tang tru6ng nhk thed khi khoa hoc ky thuat kern phat trien

• Sy tang twang nen kinh to se throe thac day tam thai khi tang Lai suit tier kiem:

Hai tinh chat dirge rut ra

• Su hei tu cUa cac nen kinh te"

• Dac tinh ngoai sinh cUa tang truOng

5.1.1 Si! hif.A to cua cac nen kinh t6

That vay, hinh 5.1 chi ra rang, khi yang bong khoa h9c cOng nghe thi luting tu ban tinh theo dau ngued se tang mot each nhat thed, khi d6 mat de tu ban trong trang thai ban dau se tha-p han mat de to ban 6 the do tang truong can bang Dieu do rut ra rang: neu hai nen kinh to c6 cling met ty le tiet kiem va chi khac nhau bed su giau c6 ye luong tu ban ban dau (hinh 5.1a) thi nen kinh to ngheo ye tien te tu ban se tang tru&ng tec de nhanh hon so \Ted nen kinh te" giau va ca hai nen kinh to nay se ding huOng t6i met mix tu ban binh quan va mdc san hrong binh quan chung tren dau ngued

Tinh chat nay van thing khi nen khoa h9c ky thuat phat trien cluvc thuc thi tren hai nen kinh te Thd nhat, trong khoang thed gian dai cac nuac ngheo can phai duei kip cac nu6c giau neu hai nen kinh te nay cling c6 met 6,7' le ti6t kiem gieng nhau Su hei to nay chi mang tinh tuong doi