Donald Davidson's essay "Mental Events" contains some of the most reasonable arguments for monism, while never feeling useless or shy because he does not ascribe to either a strict dualistic or a strictly materialistic viewpoint. While I may not want to say that I whole-heartedly agree with everything he has said in his article, I do not find much I would particularly disagree with (at least, without further analysis).
As much as materialism intrigues me, there is no denying the unknown, quantitative variables that are essentially necessary for believing with complete certainty cause a materialist to place faith in the future of science. The same fact exists for a theory related to dualism. We cannot be completely certain that the mind exists in any significant and mutually exclusive way from the body. Davidson has inevitably taken the middle ground, however his way of doing this is not foolish; he is rational and simply analyzes the way things exist as we understanding them at this present moment. One quality of his writing that intrigued me was his willingness to acknowledge that his ideas are more-so plausible theories than an exact, infallible account of how the mind/body relate. Davidson's argument primarily consists of thinking that mental events cannot be explained using strict laws. He then lends credibility to his stance by expounding on this view by considering the holism of the mental and normative.
In layman's terms, anomalous monism is a form of monism (mental events are identical with physical events) that allows room for what one may deem as "unusual" or "unexpected" given strict (scientific, physical) laws. To speak in somewhat statistical terms, where there is error (or deviation from the norm); one of two things may occur: 1). A rewriting of the null hypothesis to take into account the error (thus deeming the initial hypothesis to be false), or 2). An acknowledgement that what has occurred occurs outside of the norm, and cannot be explained even in an alternative hypothesis with statistically valid certainty. The latter is seemingly where Davidson's argument begins to take shape.
One of Davidson's initial arguments is for a version of the identity theory that denies that there can be strict laws connecting the mental and the physical. The identity theory itself is most understood in physical terms, such as lightening equaling an electrical discharge if and only if they are the same thing. Physically speaking, the identity theory makes a lot of sense; however the added depth of mental processes begins to erode at the possibility of there being "pure" identities. When one begins to correlate words such as pain with purely scientific explanations, such as: a C-fiber being fired, an area of grey begins to form because our individual concepts of "pain" seem to vary in ways not fully known. Though a materialist may desire to say that pain = a C-fiber being fired, without absolute scientific data this correlation is seemingly nothing more than speculation. It would seem that Davidson's stance is that, while pain may equal a C-fiber being fired; that does not take into account that different types of pains that can be experienced, nor the qualia of pain. Qualia in a philosophical term which is more-or-less defined as subjective experience.
He seemingly indicates that pain has its roots in the body, and is not separate (his monistic viewpoint is seen here); however there are qualities of the mental that are not captured by an A = B statement.
This may seemingly be a problem with linguistics, however it is apparent that physical events can be explained "by descriptions or open sentences that contain only the physical vocabulary.." (Davidson, 249). The flaw with a strictly physical vocabulary, however, is that lacks a description of intentionality. Being such a complex creature (a human being) gives each individual mental qualities in the form of thoughts, hopes, regrets, and similar. It is unnecessary (and perhaps impossible and irrational) to attribute mental qualities to the immaterial (at best, it is whimsical to anthropomorphize a chair), and it is still debated as to whether or not these mental events occur within lesser animals. However, the ultimate question is one that is directly related to the human animal, as they seem to be different than those other physically manifested beings and non-beings. There is seemingly no physical law that can take into account the variability of these mental states, nor is there any way to create a set of laws exclusive to mental states without requiring a return to the physical. As Davidson himself states on page 250, "...mental characteristics are in some sense dependent, or supervenient, on physical characteristics." This dependent relationship indicates that mental events may very well exist, however they require a physical source to come into existence. In essence, the physical is the creator and the mental are the created. It would seem that Davidson begins his argument by essentially accepting a functionalist stance.
To further intensify his argument, Davidson considers holism of the mental and normativity as additional support. As they relate to Davidson's essay, holism and normativity are in many ways directly connected with one another. With holism, the nature of a system cannot be understood by its parts alone. Therein lies a need for a general understanding of the system as a whole, because how the parts behave are relative to how the system behaves. With normativity, there lie similar ideas. There are norms for how things behave and function, though they are not implicitly true or false. As Davidson states on page 254, "It is not plausible that mental concepts alone can provide such a framework, simply because the mental does not...constitute a closed system." As he would have it, if we can conclude that no psychophysical statement is a strict law, then we have the "Principle of the Anomalism of the Mental: there are no strict laws at all on the basis of which we can predict and explain mental phenomena" (Davidson 254). Acknowledging the need for the whole is important, because one cannot explain mental events with strict laws; however one may conclude that mental events still do exist despite the inability for them to exist in a strict law (in essence, they fall into a non-descriptive norm).
If one event causes another, there is a strict law which those events instantiate when properly described. But it is possible (and typical) to know of the singular causal relation without knowing the law or the relevant descriptions. Knowledge requires reasons, but these are available in the form of rough heternomic generalizations, which are lawlike in that instances make it reasonable to expect other instances to follow suit without being lawlike in the sense of being indefinitely refinable (Davidson, 254).
Davidson's considerations of holism and normativity allow him to draw conclusions as it relates to mental occurrences and the bodily processes without the need for having a strict law. One can infer that based on how we function that there is a "lawlike" process to which the mind adheres, however we cannot explain this with our present-day linguistics.
Davidson's view is one that I could accept in that it explains mental processes in such a way that they are forced to adhere to the physical realm. As a monist myself, it is always fairly difficult to cope with the knowledge that we are conscious, thinking beings that can not describe everything in purely physical and scientific ways (if this were the case I would imagine human beings would not have existed for thousands of years with our current dilemma, and based on those previous thousands of years I would not speculate that the capacity for our language to mutate into one that will be solely dependent on the physical would be possible at all). As far as Davidson is concerned, I am somewhat unsure as to how his stance is all that different than a functionalist; except perhaps in the route that the conclusion is made. In both anomalous monism and functionalism the mind is described as being different from the body, yet dependent on it. He seems to need to make it known that this view is that of a monist, however functionality of a system seemingly leaves open a door for a dualist to explain the nature of the mind in a similar fashion; yet only needing to state that the mind is mutually exclusive from the body. In Davidson's essay there seems to be an unknown as to why the mind exists at all, which seemingly lends some more credibility to a strict materialist who could explain that a mind does not exist because it has no purpose if it does; or a dualist who could explain that the mind does exist but for some higher purpose.