The mind-body problem and the problem of other minds, two of the fundamental problems of the philosophy of mind, are implicitly debatable issues in modern legal systems. Folk psychology, different views on the term “free will,” and neurophysiological studies, all closely related to such philosophical issues, provide a basis for interpreting criminal law in modern legal systems. The purpose of this essay is to analyze the approaches to the philosophical questions mentioned and the effects of these approaches on criminal law. Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an original essay Dualism and monism are two opposing approaches to the mind-body problem that investigate how the mind and body interact with each other. The question is whether the mind is the same with the brain which is a part of the body or is it a separate and different entity from the brain. Dualism holds that mind and body are two separate essences, the former is non-physical and the latter is physical, and conscious intelligence is made up of non-physical essence. Furthermore, in Cartesian dualism, the mind is considered an entity completely independent of the world that people can perceive with their senses. On the other hand, monism tries to explain the mind-body problem with a single essence. Argues that mind and body are identical substances and not separate from each other. In reductive materialism, considered a form of monism, mental states are considered physical states of the brain and arise from the activities of the central nervous system. In addition to the mind-body problem, the other minds problem seeks to find an explanation for the question of how other people's mental states are perceived. In Cartesian dualism, mental states as non-physical and separate-from-the-body states are personal experiences and can be experienced distinctly from body to body. Therefore, mental states are unobservable states to an observer who does not personally experience them. In this way, philosophical behaviorism, as a reaction to dualism, considers the Cartesian vision of the mind as a "ghost in the machine". Philosophical behaviorism holds that nonphysical mental states do not exist beyond the physical one, the brain, and any mental state can be perceived by interpreting observable behaviors or circumstances. Behaviors are reflections of mental states in the physical world. Commonsense folk psychology is a theory inspired by the behaviorist approach to the problem of other minds. The theory seeks to explain and predict the mental states behind other people's behaviors. Folk psychology involves several predictions based on people's past mental behavioral experiences and accounts for causality between mental processes and behaviors. According to David Lewis, commonsense folk psychology involves statements about mental states that almost all people agree with and take to be obvious. Criminal law uses popular psychology to determine the internal states of a crime in addition to the physical ones, “actus raus”. The beliefs, desires or motivations present in the internal states of people who undertake an action play a crucial role in the criminalization of that action. As mentioned, crimes have both mental and physical elements, and intentionality is one of the significant criteria in the process of predicting mental states. Common sense folk psychology allows people to decide whether an action is taken intentionally, with purpose or not in modern legal systems. However, there are some cases where people take action withan intention that is not primarily their intention or will? Here another philosophical question comes to light which also finds its place in criminal law; problem of free will and determinism. Free will, as a definition, is controlling and determining people's actions based on their desires, intentions, and purposes. Free will is the power to freely use the mind and the power to make decisions and dictate to living beings, without any external coercion or necessity; action is the ability to initiate an action. Therefore, free will is a prerequisite for morality, personal choices, and responsibility. Cartesian dualism is an argument for free will in the sense of freedom of the mind. Arguing that the mind is a separate entity from the body and that conscious activities take place in the mind provides a basis for free will. Conscious activities are not manipulated by bodily or environmental factors because they are independent of them. On the other hand, determinism as a theory suggests that events occurring in the environment are determined by various scientific and physical laws and that these specified events must be satisfied. According to determinism everything is determined and immutable, therefore the universe is independent of the will of the observer. In this way determinism is opposed to free will. It states that the decisions, thoughts, actions, and moral preferences that people make in everyday life and consider unique to themselves are determined and are subject to strict rules. People make their decisions not consciously but based on mechanical, economic, social, historical, experimental, psychological, sociological, moral and legal determinism. Free will develops only within a causal chain in which there is no human influence, so free will is an illusion. In this context, the concepts of “caste”, “conscience” and “will” have had great importance and created much controversy in the development of criminal law. In modern legal systems the concepts of responsibility, crime and punishment cannot be mentioned without free will. Therefore, to establish a criminal legal system, free will must be presupposed. For someone to be punished it is not sufficient to find an act contrary to the law. At the same time he asks whether there is a "caste" or a "will" in committing the act. The term "guilty mind" is used to mean that an involuntary act, although against the law, will not constitute a criminal offense. In this way, determinism cannot find a place on its own in the modern legal system due to the need for free will. It can therefore be stated that incompatibility, supported above all by libertarians, does not constitute an exhaustive thesis even for criminal law. Libertarianism suggests that free will is real and certainly incompatible with determinism, so determinism must be false. However, criminal law makes use of deterministic elements in some cases such as those including “self-defense” or “incitement” and accepts the existence of free will. Consequently, both determinism and indeterminism are antagonistic as situations contrary to human reality. It is obvious, therefore, that the compatibilist thesis, which establishes a link between free will and determinism, is much more applicable to criminal law. The compatibilist thesis supports the existence of free will without rejecting the causality principle of determinism. While humans cannot determine everything with free will, it is a resource that has the potential to motivate and guide oneself through free will. Determinism and free will are not mutually exclusive, rather they are mutually conditioned. Neurological studies.