2.2. Gukoresha ubwenge mu buryo butubije
Ni ngombwa kudashyira imipaka ku busobanuro bwagutse bw’icyo twita ubushobozi bwo kumva ukuri nyakuri (reasonableness).
a) Ijambo rational akenshi rifatwa nk’aho rihwanye n’ijambo igishobora gusobanurwa (demonstrable) mu busobanuro bwaryo bukakaye. Nyamara, si ukuri ko ubunararibonye bwose bwa muntu ku bijyanye no kumva ukuri bubarizwa muri iryo huza gusa. Nubwo bidashidikanywaho ko ishyira-mu-gaciro rishaka, ryifuza, kandi ryiyumvamo amatsiko yo kugaragaza buri kintu, ntabwo ari byo kuvuga ko ukuri gusobanutse guhwanye n’igishobora gusobanurwa. Ubushobozi bwo gusobanura ni kimwe mu bigize gushyira mu gaciro, ariko gushyira mu gaciro ntibigarukira gusa ku bushobozi bwo gusobanura.
None se gusobanura bivuga iki? Bivuga gusubiramo intambwe zose zigize inzira ikintu cyanyuzemo kikabaho. Ku ishuri, mu gihe cyo kugaragaza inyigisho (théorème), iyo hagize intambwe isimbukwa, umwarimu ahita ahagarika agira ati: “Ibi ntibyagaragajwe.” Mu by’ukuri, intambwe zose zigize ukuri kw’ikintu zigomba gusubirwamo kugira ngo tuvuge ko habayeho gusobanura koko.
Ariko ibi ntibihagije gusobanura byimbitse icyo gushyira mu gaciro bisobanura, kuko cyane cyane ibintu by’ingenzi kandi by’umwimerere mu by’ukuri bidashobora kugaragazwa. Inzira twavuze haruguru ntishobora gukoreshwa kuri ibyo bintu. Urugero, ntidushobora gusobanura uko ibintu bibaho, nyamara igisubizo cy’ikibazo cy’uko ibintu bibaho ni cyo kidushishikaje cyane kurusha ibindi. N’iyo twagaragaza ko ameza runaka akozwe mu kintu gifite imiterere n’imivanze byihariye, ntitwashobora na rimwe gusubiramo intambwe zose zatumye ayo meza abaho.
b) Gushyira mu gaciro ntibigomba kwitiranywa n’imyumvire ya logic. Logic ni ihame ryo guhuza neza ibitekerezo; iyo ushyizeho amahame runaka (premises) ukayongeraho amashami mu buryo buhuje, ugera ku mwanzuro uhuje n’imyumvire ya logic. Ariko iyo ayo mahame aba atari yo, logic itunganye ishobora gutanga umwanzuro utari wo.
Ikibazo kidushishikaje by’ukuri si logic—nubwo ari umukino w’ubwenge ushimishije—cyangwa kugaragaza/gusobanura—nubwo bikurura amatsiko—ahubwo ni ukuntu twafatana n’ukuri ubwako, tukamenya ukuri kw’ibintu. Ibi ni ikibazo cyo gukururwa n’ukuri ubwabyo, si ikibazo cyo guhuza ibitekerezo bya logic gusa. Kumenya no kwemera urukundo umubyeyi afitiye umwana we si umusaruro w’urukurikirane rw’imyumvire ya logic; ni ikigaragara, ni icyemezo kidashidikanywaho, cyangwa ni igitekerezo n’ihamagarwa bituruka ku by’ukuri ubwabyo, ibyo umuntu aba agomba kwemera ko bihari byanze bikunze. Kubaho kw’ameza nkoreraho, urukundo mama wanjye amfitiye—nubwo bitaba ari imyanzuro yagezweho binyuze mu myumvire ya logic iteguye neza—ni ibintu bifatika bihuye n’ukuri, kandi birumvikana kubyemeza. Logic, guhuza ibitekerezo, n’igaragaza (demonstration) si ibirenze kuba ibikoresho by’ugushyira mu gaciro, bikorera mu nyungu z’ikintu kinini kurushaho, ari cyo “umutima” mugari ubyifashisha.
Icyitonderwa (Nota bene): Ntekereza ko ari ingenzi gushyira imbaraga nyinshi ku ijambo gushyira mu gaciro kuruta ku ijambo ubwenge (reason) ubwabwo. Koko rero, ubwenge—ubwo bushobozi bwo kumenya no gusobanukirwa n’ukuri—nabwo bushobora gukoreshwa mu buryo butari mu gaciro, ni ukuvuga, hatabayeho impamvu zihagije.
Icyakora, imizi y’ikibazo iri mu gitekerezo cy’ubwenge ubwabwo. Ndifuza kuvuga inkuru y’ikintu cyambayeho mu myaka yashize, cyampaye isomo rikomeye. Nari ngiye kwigisha isomo ry’iyobokamana bwa mbere mu ishuri ryisumbuye rya kera (classical lyceum). Nkimara kugera ku meza yanjye, kandi ntaranabona umwanya wo kuvuga, nabonye umwana azamuye ukuboko mu murongo w’inyuma. Nabajije uwo munyeshuri icyo yashakaga. Ansubiza muri rusange, aya magambo:
“Munyihanganire, Mwarimu, ariko nta kamaro ko muza hano kutubwira iby’iyobokamana, cyangwa kugerageza gutekereza ku kwemera, kuko ubwenge n’iyobokamana bigize isi ebyiri zitandukanye rwose. Ibyavugwa ku iyobokamana ntaho bihuriye n’imikoreshereze y’ubwenge, kandi n’ubwenge ntaho buhuriye n’iyobokamana; bityo rero, kugerageza gutekereza ku iyobokamana mu bwenge ni ukwibeshya no kuyobya.”
Nabajije uwo munyeshuri icyo iyobokamana risobanura kuri we; ntiyagira igisubizo. Nuko mbaza icyo kibazo ishuri ryose, na bwo igisubizo kirabura. Icyo gihe, nabajije uwo munyeshuri wo mu murongo w’inyuma gusobanura icyo ubwenge ari cyo; na none araceceka. Nongera mbaza ishuri ryose, na bwo nsanganirwa no guceceka.
Hanyuma ndababaza nti: “Ni gute mushobora gufata umwanzuro ku kibazo cy’iyobokamana n’ubwenge mutarabanje kugerageza gusobanukirwa icyo ari cyo? Mukoresha rero amagambo mutazi neza icyo asobanura.”
Nk’uko byari byitezwe, iryo jambo ryanjye ryabyukije impaka zikomeye, maze nsobanukirwa kurushaho ko umwarimu wa filozofiya yari yaragize uruhare runaka mu mitekerereze y’abo banyeshuri. Mvuye mu ishuri isomo rirangiye, nahuye n’uwo mwarimu. Tugihura namubwiye ko natangajwe n’uko abanyeshuri bafataga nk’aho byumvikana ko iyobokamana ridashobora kugira aho rihurira n’ubwenge. Igisubizo cye cyari uko Kiliziya ubwayo yari yaravuze ikintu nk’icyo mu Nama Nkuru ya Kabiri yaberreye muri Orange.
Namwibukije ko buri jambo rigomba gusobanurwa hashingiwe ku mateka n’igihe ryavuzwemo, ku bitekerezo n’impungenge by’icyo gihe. Gukura interuro mu muco n’imiterere yanditswemo, hanyuma ukayisoma nk’aho yanditswe uyu munsi, ni ukurenga ku mategeko shingiro y’amateka, kandi ntibituma isobanuka neza uko bikwiye. Icyo gihe, impaka zari zimaze kwaguka, maze itsinda ry’abanyeshuri bari badukikije rirushaho kwiyongera, ariko n’ubwo igihe cyo kujya mu rindi somo cyari kigeze, nifuzaga ko abanyeshuri basobanukirwa neza ishingiro ry’impaka zari hagati y’umwarimu wa filozofiya nanjye. Ni uko ndamumubaza nti:
“Mwarimu, sinigeze njya muri Amerika, ariko nshobora kubabwira nizeye neza ko Amerika ihari. Ibi mbivuga n’icyizere kimwe n’icyo mfite mvuga ko muhagaze imbere yanjye uyu mwanya. Ese mwumva ko icyo cyizere cyanjye gishyira mu gaciro?”
Nyuma y’akanya agacecetse no kugaragaza gushidikanya, igisubizo cye cyari: “Oya.” Aha ni ho nashakaga kugera ngo abanyeshuri babyumve neza, kandi ni na byo nshaka gusobanura neza hano: uko numva ubwenge (reason) bikubiyemo igitekerezo cy’uko bishobora kuba ari byo byumvikana kurusha ibindi byo kwemera ko Amerika iriho n’iyo waba utarayibonye n’amaso. Ku rundi ruhande, uko uwo mwarimu yatekerezaga ku bwenge byamuteye kuvuga ko icyo atari igitekerezo gifite ishingiro.
Kuri jye, ubwenge ni ugufungukira ukuri, ni ubushobozi bwo gufata no kwemeza ukuri mu nzego zose kukugize. Kuri uwo mwarimu wundi, ubwenge ni “igipimo” cy’ibintu, kandi ikintu kiba ari ukuri gusa iyo gishobora kugaragazwa mu buryo butaziguye.
