?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rft.title=Some+Expert+Systems+Need+Common+Sense&rft.creator=McCarthy%2C+J&rft.subject=Artificial+Intelligence&rft.description=An+expert+system+is+a+computer+program+intended+to+embody+the+knowledge+and+ability+of+an+expert+in+a+certain+domain.+The+ideas+behind+them+and+several+examples+have+been+described+in+other+lectures+in+this+symposium.+Their+performance+in+their+specialized+domains+are+often+very+impressive.+Nevertheless%2C+hardly+any+of+them+have+certain+common+sense+knowledge+and+ability+possessed+by+any+non-feeble-minded+human.+This+lack+makes+them+%60%60brittle''.+By+this+is+meant+that+they+are+difficult+to+extend+beyond+the+scope+originally+contemplated+by+their+designers%2C+and+they+usually+don't+recognize+their+own+limitations.+Many+important+applications+will+require+common+sense+abilities.+The+object+of+this+lecture+is+to+describe+common+sense+abilities+and+the+problems+that+require+them.++Common+sense+facts+and+methods+are+only+very+partially+understood+today%2C+and+extending+this+understanding+is+the+key+problem+facing+artificial+intelligence.++This+isn't+exactly+a+new+point+of+view.+I+have+been+advocating+%60%60Computer+Programs+with+Common+Sense''since+I+wrote+a+paper+with+that+title+in+1958.+Studying+common+sense+capability+has+sometimes+been+popular+and+sometimes+unpopular+among+AI+researchers.+At+present+it's+popular%2C+perhaps+because+new+AI+knowledge+offers+new+hope+of+progress.+Certainly+AI+researchers+today+know+a+lot+more+about+what+common+sense+is+than+I+knew+in+1958+--+or+in+1969+when+I+wrote+another+paper+on+the+subject.+However%2C+expressing+common+sense+knowledge+in+formal+terms+has+proved+very+difficult%2C+and+the+number+of+scientists+working+in+the+area+is+still+far+too+small.++One+of+the+best+known+expert+systems+is+MYCIN+(Shortliffe+1976%3B+Davis%2C+Buchanan+and+Shortliffe+1977)%2C+a+program+for+advising+physicians+on+treating+bacterial+infections+of+the+blood+and+meningitis.+It+does+reasonably+well+without+common+sense%2C+provided+the+user+has+common+sense+and+understands+the+program's+limitations.++MYCIN+conducts+a+question+and+answer+dialog.+After+asking+basic+facts+about+the+patient+such+as+name%2C+sex+and+age%2C+MYCIN+asks+about+suspected+bacterial+organisms%2C+suspected+sites+of+infection%2C+the+presence+of+specific+symptoms+(e.g.+fever%2C+headache)+relevant+to+diagnosis%2C+the+outcome+of+laboratory+tests%2C+and+some+others.+It+then+recommends+a+certain+course+of+antibiotics.+While+the+dialog+is+in+English%2C+MYCIN+avoids+having+to+understand+freely+written+English+by+controlling+the+dialog.+It+outputs+sentences%2C+but+the+user+types+only+single+words+or+standard+phrases.+Its+major+innovations+over+many+previous+expert+systems+were+that+it+uses+measures+of+uncertainty+(not+probabilities)+for+its+diagnoses+and+the+fact+that+it+is+prepared+to+explain+its+reasoning+to+the+physician%2C+so+he+can+decide+whether+to+accept+it.++Our+discussion+of+MYCIN+begins+with+its+ontology.+The+ontology+of+a+program+is+the+set+of+entities+that+its+variables+range+over.+Essentially+this+is+what+it+can+have+information+about.++MYCIN's+ontology+includes+bacteria%2C+symptoms%2C+tests%2C+possible+sites+of+infection%2C+antibiotics+and+treatments.+Doctors%2C+hospitals%2C+illness+and+death+are+absent.+Even+patients+are+not+really+part+of+the+ontology%2C+although+MYCIN+asks+for+many+facts+about+the+specific+patient.+This+is+because+patients+aren't+values+of+variables%2C+and+MYCIN+never+compares+the+infections+of+two+different+patients.+It+would+therefore+be+difficult+to+modify+MYCIN+to+learn+from+its+experience.++MYCIN's+program%2C+written+in+a+general+scheme+called+EMYCIN%2C+is+a+so-called+production+system.+A+production+system+is+a+collection+of+rules%2C+each+of+which+has+two+parts+--+a+pattern+part+and+an+action+part.+When+a+rule+is+activated%2C+MYCIN+tests+whether+the+pattern+part+matches+the+database.+If+so+this+results+in+the+variables+in+the+pattern+being+matched+to+whatever+entities+are+required+for+the+match+of+the+database.+If+not+the+pattern+fails+and+MYCIN+tries+another.+If+the+match+is+successful%2C+then+MYCIN+performs+the+action+part+of+the+pattern+using+the+values+of+the+variables+determined+by+the+pattern+part.+The+whole+process+of+questioning+and+recommending+is+built+up+out+of+productions.++The+production+formalism+turned+out+to+be+suitable+for+representing+a+large+amount+of+information+about+the+diagnosis+and+treatment+of+bacterial+infections.+When+MYCIN+is+used+in+its+intended+manner+it+scores+better+than+medical+students+or+interns+or+practicing+physicians+and+on+a+par+with+experts+in+bacterial+diseases+when+the+latter+are+asked+to+perform+in+the+same+way.+However%2C+MYCIN+has+not+been+put+into+production+use%2C+and+the+reasons+given+by+experts+in+the+area+varied+when+I+asked+whether+it+would+be+appropriate+to+sell+MYCIN+cassettes+to+doctors+wanting+to+put+it+on+their+micro-computers.+Some+said+it+would+be+ok+if+there+were+a+means+of+keeping+MYCIN's+database+current+with+new+discoveries+in+the+field%2C+i.e.+with+new+tests%2C+new+theories%2C+new+diagnoses+and+new+antibiotics.+For+example%2C+MYCIN+would+have+to+be+told+about+Legionnaire's+disease+and+the+associated+Legionnella+bacteria+which+became+understood+only+after+MYCIN+was+finished.+(MYCIN+is+very+stubborn+about+new+bacteria%2C+and+simply+replies+%60%60unrecognized+response''.)++Others+say+that+MYCIN+is+not+even+close+to+usable+except+experimentally%2C+because+it+doesn't+know+its+own+limitations.+I+suppose+this+is+partly+a+question+of+whether+the+doctor+using+MYCIN+is+trusted+to+understand+the+documentation+about+its+limitations.+Programmers+always+develop+the+idea+that+the+users+of+their+programs+are+idiots%2C+so+the+opinion+that+doctors+aren't+smart+enough+not+to+be+misled+by+MYCIN's+limitations+may+be+at+least+partly+a+consequence+of+this+ideology.++An+example+of+MYCIN+not+knowing+its+limitations+can+be+excited+by+telling+MYCIN+that+the+patient+has+Cholerae+Vibrio+in+his+intestines.+MYCIN+will+cheerfully+recommend+two+weeks+of+tetracycline+and+nothing+else.+Presumably+this+would+indeed+kill+the+bacteria%2C+but+most+likely+the+patient+will+be+dead+of+cholera+long+before+that.+However%2C+the+physician+will+presumably+know+that+the+diarrhea+has+to+be+treated+and+look+elsewhere+for+how+to+do+it.++On+the+other+hand+it+may+be+really+true+that+some+measure+of+common+sense+is+required+for+usefulness+even+in+this+narrow+domain.+We'll+list+some+areas+of+common+sense+knowledge+and+reasoning+ability+and+also+apply+the+criteria+to+MYCIN+and+other+hypothetical+programs+operating+in+MYCIN's+domain.&rft.date=1984&rft.type=Preprint&rft.type=NonPeerReviewed&rft.format=application%2Fpostscript&rft.identifier=http%3A%2F%2Fcogprints.org%2F423%2F2%2Fsomeneed.ps&rft.identifier=++McCarthy%2C+J++(1984)+Some+Expert+Systems+Need+Common+Sense.++%5BPreprint%5D+++++&rft.relation=http%3A%2F%2Fcogprints.org%2F423%2F