Hard incompatibilism is defended by Derk Pereboom, who identifies a variety of positions where free will is seen irrelevant to indeterminism/determinism, among them the following: Determinism (D) is true, D does not imply we lack free will (F), but in fact we do lack F. D is true, D does not imply we lack F, but in fact we don't know if we have F. D is true, and we do have F. D is true, we have F, and F implies D. D is unproven, but we have F. D isn't true, we do have F, and would have F even if D were true. D isn't true, we don't have F, but F is compatible with D. Derk Pereboom, Living without Free Will,[13] p. xvi. Pereboom calls positions 3 and 4 soft determinism, position 1 a form of hard determinism, position 6 a form of classical libertarianism, and any position that includes having F as compatibilism. He largely ignores position 2

Compatibilist models of free will often consider deterministic relationships as discoverable in the physical world (including the brain). Cognitive naturalism[118] is a physicalist approach to studing human consciousness in which mind is simply part of nature, perhaps merely a feature of many very complex self-programming feedback systems (for example, neural networks and cognitive robots), and so must be studied by the methods of empirical science, for example, behavioral science and the cognitive sciences like neuroscience and cognitive psychology.[101][119] Cognitive naturalism stresses the role of neurological sciences. Overall brain health, substance dependence, depression, and various personality disorders clearly influence mental activity, and their impact upon volition also is important.[113] For example, an addict may experience a conscious desire to escape addiction, but be unable to do so. The "will" is disconnected from the freedom to act. This situation is related to an abnormal production and distribution of dopamine in the brain.[120] The neuroscience of free will places restrictions on both compatibilist and incompatibilist free will conceptions. Compatibilist models adhere to models of mind in which mental activity (such as deliberation) can be reduced to physical activity without any change in physical outcome. Although compatibilism is generally aligned to (or is at least compatible with) physicalism, some compatibilist models describe the natural occurrences of deterministic deliberation in the brain in terms of the first person perspective of the conscious agent performing the deliberation.[7] Such an approach has been considered a form of identity dualism. A description of "how conscious experience might affect brains" has been provided in which "the experience of conscious free will is the first-person perspective of the neural correlates of choosing".[7]