Logic corresponds to reasoning based on reason. This cognitive ability is located in the left cerebral hemisphere and frontal brain regions. Lesions in these regions result in disassociation or disintegration of logic.
What is logic?
Logic is among the cognitive abilities of humans and corresponds to reasoning based on reason. Logic is among the cognitive faculties of humans and corresponds to consequential reasoning based on reason. Logical reasoning is a specifically human ability. No other species thinks in this way. Traditionally, philosophy in particular has been concerned with human logic, sometimes recognizing this type of thinking as erroneous because it loses validity outside of the human species. Medicine localizes human logic to the left hemisphere of the brain, where language, calculation, rules, laws and general ratio are located. The frontal regions of the brain are especially decisive for the logic of the brain. Thus, neuroscience has now recognized the frontal brain as the seat of cognitive and specifically human abilities. Thus, the neural circuitry of the frontal brain regions shapes the personal logic of the individual. The specific wiring patterns can change as a result of learning experiences and drastic experiences.
Function and task
Philosophy knows different approaches to logic. For example, the statement that every statement has one of two truth values and can be said to be either true or false is known as classical logic. In addition to this bivalence principle, classical logic postulates that the truth value of compound statements is uniquely determined by that of their partial statements and by their combination. In addition to the bivalence and extensionality principles of classical logic, philosophy is concerned with determining criteria for the validity of individual conclusions and the logical value of statements. Logic has medical relevance especially in the neurosciences. The ability to think logically is what makes a human being and is a task of the left brain hemisphere. In discussions it often turns out that two people can follow completely different principles of logic. The general predisposition to logical reasoning is genetically given to every human being. However, the actual expression of the individual logic is only formed in the course of life and can be significantly influenced by personal experiences. Neuroscience interprets this influence as changes in the neuronal circuits as they are relevant for learning experiences and drastic experiences of the individual. The brain consists of a network of individual neurons between which there is connectivity. Synaptic connections are fundamentally changeable and thus follow the principle of neuronal plasticity. Neuroscience traces logic back to the area of the frontal brain. According to modern medicine, this brain region is home to all the abilities that make a person human. Thus, in addition to consciousness and social behavior, logic is also located in the synaptic connections of this brain region. Logic thus corresponds in a multi-valued sense to a certain type of thinking. Thinking, in turn, is a particular network of connection patterns between individual neurons in the human brain.
Diseases and ailments
Lesions in the frontal regions of the brain can permanently alter or disintegrate an individual’s ability to think logically. Most often, frontal brain lesions are additionally accompanied by character changes. Only rarely do they affect cognitive abilities exclusively. Lesions in the frontal brain may be due to traumatic brain injury, stroke, tumor disease, inflammatory processes, viral infections, or degenerative diseases. The frontal brain region does not necessarily have to be directly affected. Often, lesions in the individual projection pathways between the frontal brain and other brain regions are sufficient. Changes in these regions of the brain are also observed, for example, in people with schizophrenia or alcohol addiction. In some cases, the lesions manifest in pseudopsychipathic or pseudosociopathic features. Sometimes they are also pseudodepressive traits.Because cognitive abilities such as logic are a large part of character, relatives often describe character changes in people with frontal brain lesions. The loss of logic can result in strange-seeming actions and alienate the person’s way of thinking to such an extent that his or her opinions, beliefs, and knowledge of the world are no longer comprehensible to others. The frontal brain region is also where statements or actions are planned, for example. In the case of a lesion in this brain region, any actions of the affected person are sometimes no longer based on any logical potential. The affected person no longer recognizes the lack of logic in his actions and statements and considers them to be logical himself. An example of the decay of logic, the decay of cognition and ultimately the complete ego decay are the degenerative changes in the frontal brain that can be caused by diseases such as Alzheimer’s disease. In the case of tumor diseases, viral infections or inflammatory lesions and brain hemorrhages, logic together with the actual character of the affected person can often be restored at least in part by adequate therapy.
