In the piece under review, Putnam seeks to investigate the nature of pain, specifically, to identify whether it is a brain state or not. He highlights the dissimilarity of brain structure in various forms of life through the example of an octopus and a mammal, from which the difference in their “physical-chemical” functionality emerges (Putnam, p. 56). Simply stated, the ways activity occurs in the brain may differ from one type of it to another. This, according to Putnam, drives to the conclusion that physical responses most living creatures demonstrate, including pain, are not exclusively brain states. An essential nuance, at which the thinker points, is that such reactions normally manifest themselves in particular behavior that enables detecting the state. For instance, it is possible to guess that a certain organism is experiencing pain, hunger, uncomfortable temperature, or other from its movements or the sounds it is emitting (Putnam, p. 56). This serves to prove that the states are not limited to changes in brain activity, but can also determine its bodily equivalent; therefore, it is more reasonable to consider them complex. Specifically, the term Putnam offers to classify basic physiological response to irritants, which interfere with the well-being of an organism, is “a functional state” (p. 54). His hypothesis tells that to feel pain, a living creature needs to possess an appropriate type of functional organization, which actually determines this condition, making it physically possible. In the simplest terms, Putnam rejects the identical nature of mental and physical properties, which two hypothetically are intertwined up to inseparability. Horowitz mentions that such a viewpoint falls under the philosophy of “type-physicalism” (p. 81). Meanwhile, Putnam labels it “the brain state theory” (p. 55). His main argument against it, as mentioned, rests on the fact that mental conditions can have various behavioral manifestations, therefore, they hardly share certain physical nature. Putnam’s view doubtlessly is closer to reality in comparison with type-physicalism, primarily because of sufficient practical evidence. In fact, different creatures may act dissimilarly when in pain; thus, they may twitch or shrink, cry, moan, or squeeze, or other. Furthermore, several species, including humans but not limited to them, can camouflage their discomfort to avoid becoming excessively vulnerable. These are the examples to illustrate that physiology-based response to irritants, such as pain, is “multiply realizable” (Horowitz, p. 82). This assumption, in turn, separates mental properties from physical since otherwise, all creatures that are able to feel pain would behave identically. It is worth noting that some philosophers attempted to compromise the validity of Putnam’s argument, proclaiming that, although the nature of pain apparently is different in various species, it is identical in one. This statement, however, is false as well; empirical data show that the functional structure of brain, including human, can transform. For instance, a serious injury of particular brain areas can lead to a situation where the other begin to perform their functions, so that the orga