insists on the derivability of all terms in the theory to be reduced from terms in the reducing theory and the bridging laws, as the canonical theory of reduction. Given generalized multiple realizability, the physical science part of these psychophysical bridge laws will end up being a (possibly infinite) disjunction of all the terms referring to possible physical realizations of a mental kind. This disjunction cannot be a kind-predicate and therefore the entire statement cannot be a law of physics. The special sciences therefore cannot be reduced to physics. Functionalism, which attempts to identify mental kinds with functional kinds that are characterized exclusively in terms of causes and effects, abstracts from particle physics and hence seems to be a more suitable explanation of the relation between mind and body. As a result of these arguments and others that build upon them, the dominant theory in philosophy of mind since the 1960s has been a version of non-reductive physicalism based on multiple realizability. In 1988, Hilary Putnam used multiple realizability to argue against functionalism. Noting that functionalism is essentially a watered-down reductionist or identity theory in which mental kinds are ultimately identified with functional kinds, Putnam argues that mental kinds are probably multiply realizable over functional kinds. The same mental state or property can be implemented or realized by different states of a universal Turing machine. Arguments for multiple realizability The conceivability argument Putnam asks whether alien beings, artificially intelligent robots, and silicon-based life forms should be considered a priori incapable of experiencing pain merely because they do not have the same neurochemistry as humans. We can imagine that they might share our psychological states despite being made of different stuff. Our ability to conceive of that possibility means that multiple realizability is possible. The likelihood argument Putnam cites examples from the animal kingdom as evidence for the multiple realizability of mental states. Evolutionary biology — including evolutionary neuroscience — and comparative neuroanatomy and neurophysiology have demonstrated that mammals, reptiles, birds, amphibians, and mollusks have different brain structures. These animals can only share the same mental states and properties if these mental states and properties can be realized by different physical states in different species. Putnam concludes that type-identity and other reductive theories make an extremely "ambitious" and "highly implausible" conjecture that can be disproven with just one example of multiple realizability. On the contrary, it is likely that creatures that