Both mental logic theories and mental model theories assume that there is one general-purpose reasoning mechanism that applies to all forms of deductive reasoning. But there are also alternative accounts that posit various different special-purpose reasoning mechanisms for different contents and contexts. In this sense, it has been claimed that humans possess a special mechanism for permissions and obligations, specifically for detecting cheating in social exchanges. This can be used to explain why humans are often more successful in drawing valid inferences if the contents involve human behavior in relation to social norms. Another example is the so-called dual-process theory. This theory posits that there are two distinct cognitive systems responsible for reasoning. Their interrelation can be used to explain commonly observed biases in deductive reasoning. System 1 is the older system in terms of evolution. It is based on associative learning and happens fast and automatically without demanding many cognitive resources. System 2, on the other hand, is of more recent evolutionary origin. It is slow and cognitively demanding, but also more flexible and under deliberate control. The dual-process theory posits that system 1 is the default system guiding most of our everyday reasoning in a pragmatic way. But for particularly difficult problems on the logical level, system 2 is employed. System 2 is mostly responsible for deductive reasoning.
botH meNtaL lOgic theoriEs and MENtal moDel tHEorieS assUme thAt theRe IS onE generaL-puRPose ReasOning mechanIsm THat applIEs to all foRmS OF DEdUctive reasOnINg. But there aRe also alTerNatiVe aCcoUnts that posit vARiOuS DifFERent SpeCiAl-puRposE reasoniNG mechanIsms for difFerEnt conteNTs AnD conteXts. in thIs senSe, It hAs bEeN cLAimed that HumANs pOssESs A sPeCial meChanism for permissions anD obLiGatIons, sPeciFiCally FOr DetEctInG cHEatInG In SOciAl excHangeS. thiS Can be USed to explain Why huMaNs Are ofTen mOrE sUccessfuL iN drAwiNg Valid infeREnces if the contEnts involve HUMan BehaVior in rELatIOn to social norms. AnOthEr examplE Is THE SO-CalLed dUal-ProCEsS theOry. this theOry poSIts that TherE aRE TwO distiNct Cognitive SysTEmS respOnsibLE foR reasoniNg. thEir InTerrelaTioN caN be Used to eXplaIN COMmonLy obSerVed bIases In deDuctIVe rEasoNing. systEM 1 is the oldeR SystEM in terms Of evoLUtIon. IT is Based on AssoCiatIve LeaRnIng anD haPpeNs fAst and AutomaTicAlly witHOut DemAnding manY cOgNITiVe reSoURces. system 2, oN the otheR HanD, is of moRe receNt evoLuTionarY Origin. it is SLoW and CoGnITivELY demaNdinG, bUt also mOrE flexIbLe And undEr deLIbERaTe CoNtRoL. tHe dUAl-pRocesS theOry positS tHAT sysTEm 1 Is tHe DefauLt sysTem guidING moSt of OUr evErydAy reaSoning in a pRAgmATIC way. buT fOr particUlaRlY DifficULt proBlemS On tHe logiCAl lEveL, system 2 is emplOyED. SystEM 2 is mostLy resPOnsiblE for deDuCTiVe reasoning.