Classical Indian Philosophy of Mind: The Nyaya Dualist Tradition (review)

This book is an exposition and defense of classical Nyāya-Vaiśṣika psychophysical dualism, the theory that mind and matter are ontologically different and irreducible to each other. Traditionally Naiyāyikas are substance dualists, holding that the self (ātman) is a permanent, immaterial substance that possesses perceptible qualia like cognition and desire. However, Nyāya substance dualism is importantly different from Cartesian substance dualism; it is also different from other forms of Indian substance dualism, like Sāṃkhya.

In fourteen chapters Chakrabarti explains Nyāya dualism's ontological presuppositions and expounds the many arguments that Naiyāyikas offer for their theory. Chapter 1 briefly outlines the background Nyāya ontology and epistemology. Among the seven fundamental categories admitted by the Nyāya are substances (dravya) and qualia (guṇa). Substances can be physical (bhautika) or spiritual (cetana), and the self is held to be a spiritual substance. Conscious states are qualia of the underlying self, which can exist without them. Nyāya epistemology is causal-reliabilist and admits perception, inference (inductive and deductive), and testimony as reliable means of knowledge. In order to justify their dualism Naiyāyikas utilize a set of arguments that draw upon all of these recognized means of knowledge.

Chapter 2 distinguishes Nyāya dualism from Cartesian dualism, arguing that Nyāya interactionists do not have Descartes' interaction problem because (1) they allow that the immaterial self has location although not extension, and (2) they embrace a "Hume-like" account of causation. This is debatable. First, I agree that a plausible dualism needs to allow that immaterial minds are located, even if they have no dimension. Moreover, there is a sense in which this concession just takes a little further the implications of Descartes' own belief that the nonspatial mind worked through a particular material place in the body: the pineal gland. However, if the immaterial-location claim is to be intelligible, the dualist also owes us a developed ontology of immaterial points that are distinct from material points, even though the spatial properties of the two kinds of points are indistinguishable.

Second, while it has often been noted that Descartes has no interaction problem if causation is nothing but Humean constant conjunction and we can observe both mental and physical events, many philosophers have well-motivated reservations about such a general account of causation. Moreover, it is unclear to me that the Nyāya theory of causation really is "Hume-like" (p. 26): there seems to be a distinctly non-Humean type of (non-logical) necessity implied by the Nyāya insistence that a cause is an invariable (niyata) and non-superfluous (ananyathāsiddha) antecedent of an effect.

Chapters 3 and 4 explain the Nyāya view of cognitions and other internal states as qualia of an immaterial substantial self. The internal states discussed in most detail are cognition, pleasure, pain, and desire. Chakrabarti suggests that the Nyāya account of these states may loosely be called "functionalist" in that their nature is explained in terms of their causal roles. The self (as an immaterial and extended substance) is then introduced in a functionalist fashion in order to explain the kind of contact that has a causal role in the origin of an internal state like pleasure.

Chapters 5 through 10 expound the Nyāya view of the self and its relation to the body, presenting a battery of traditional arguments. The Nyāya view of the self as the permanent substratum of the fleeting internal states is antithetical to the kind of "bundle theory" espoused by Indian Buddhists (and by many modern Western philosophers). Accordingly, Naiyāyikas have always felt the need to argue extensively for this part of their theory. Since they hold that the self is not perceived, they try to build an inferential case for its existence. First, they argue that the self is a permanent entity, then that this permanent entity is a substance. Finally, they...