Abstract

This paper explores the causes of the unique individual patterns of reaction we call personality and compares the view that these are determined by the individual’s soul with the view that biological factors are responsible for personality characteristics. The paper discusses current evidence for genetic influences on temperament, psychopathology, and intelligence and examines complexities such as the influence of environment and epigenetic factors. It concludes that in all likelihood our unique personality traits are determined by biological factors alone, without any need to appeal to a nonmaterial or ethereal element. 1. Confirming Nonexistence -- 2. What is a Soul? -- 3. Personality, Soul, and Behavior Genetics -- 4. Measuring Personality - 4.1 Temperament - 4.2 Psychopathology - 4.3 Intelligence -- 5. Examining the Genotype and Its Effects - 5.1 The Human Genome - 5.2 Polygenic Effects - 5.3 Epigenesis and Imprinting - 5.4 Gene-Environment Interactions - 5.5 Evolutionary Psychology -- 6. Connections between Genotype and Behavioral Phenotype - 6.1 Temperament - 6.2 Psychopathology - 6.3 Intelligence -- 7. Conclusion: The Principle of Parsimony Undermines Soul Theory