This text is concerned with the problem of the reciprocity between logic and human reasoning. This problem is illustrated with implementation of the theory of Wilhelm Wundt and a concrete investigation of the reasoning of people with autism and attention deficit hyperactivity disorder (ADHD) undertaken by Keith Stenning and Michiel van Lambalgen as case studies. On the one hand, the analysis of these cases reveals which of Wundt’s ideas are currently important for philosophy of logic and psychology. On the other hand, it shows the difference between the classical psychologism and the neopsychologism.
Frege appears to hold both (a) that thoughts are internally articulated, in a way that mirrors the semantic articulation of the sentences that express them, and (b) that the same thought can be analyzed in different ways, none of which has to be more fundamental than the others. Commentators have often taken these theses to be mutually incompatible and have tended to polarize into two camps, each of which attributes to Frege one of the theses, but maintains that he is only apparently committed to the other. This paper argues (i) that there are good exegetical and philosophical reasons for reconciling the two theses; (ii) that this reconciliation can be achieved by rejecting an assumption shared by the two opposite camps of the exegetical debate, i.e., the assumption that essential articulatedness implies unique articulation; and finally (iii), that this crucial assumption can be resisted by appreciating Frege’s anti-atomistic and ‘organic’ conception of the internal complexity of thoughts.
This paper presents two major aspects of Frege’s and Peirce’s views on assertion and denial: first, their arguments for the notational choices concerning the representation of assertion and denial in Begriffsschrift (BS) and Existential Graphs (EGs), respectively; and second, those properties of BS and EGs which reflect their inventors’ views on assertion and denial. We show that while Frege’s notation has an ad hoc sign of assertion and an ad hoc sign of negation, Peirce has a sign of assertion which is also a sign of logical conjunction, and a sign of scope which is also a sign of negation.
Due to some recent researches the problem of the reciprocity of logic and psychology got back into the philosophy of logic. Logicians and psychologists reconsider the relations between the logical laws and the human reasoning and deny the idea expressed by antipsychologists that exploration of the human reasoning is non-informative for logical theory. In the course of the controversy over psychologism at the turn of the XXth century some thinkers claimed that these disciplines were strongly connected. Some current researchers united under the name “Neopsychologism”. The article covers the problem of the reciprocity between logic and psychology in terms of Wilhelm Wundt’s theory and the Keith Stenning and Michiel van Lambalgen’s case research of reasoning peculiar to children with autism.
Wundt was not a typical psychologist. He argued that the laws of logic and the laws of thought should be strongly separated. His idea of the correlation between the thought process and the other cognitive functions is “heuretic” as well. Despite that – or thanks to that - his theory is prolific. Its analysis and comparison with the recent logical researches show the difference between the classical psychologism and the neopsychologism. The article also reveals which of Wundt’s ideas are still important for philosophy of logic and psychology today.