Nominalism and Realism

In gearing up for posts on critical realism I have been thinking a lot about nominalism and realism as foundational beliefs about the world. They are not classically juxtaposed - though I have found several interesting readings on the topic regarding CS Peirce’s writings and his system of thought.

Going to the ODP - nominalism is “the view that things denominated by the same term share nothing except that fact: what all chairs have in common is that they are called ‘chairs.’ The doctrine is usually associated with the thought that everything that exists is a particular individual, and therefore there are no such things as universals.” “A universal is a property or relation that can be instanced or instantiated by a number of particular things.” In other words, nominalism denies the existence of what I have been calling “general premises.”

C.S. Peirce saw realism as an argument against nominalism. While there are varieties of realism, a common core for all realists is the affirmation of “the real existence of some kind of thing or some kind of fact or affairs.” (ODP) Peirce (and others) saw that nominalism was damaging to epistemology. I can see a connection between Hume’s problem of induction and the argument against our knowledge of causation and nominalism. If we cannot mentally (rationally) interpret empirical evidence from particulars as having an underlying universal causal relation then we cannot have universals. In many ways nominalism comes from empiricism. If all you can know is what you can sense as experience, then you cannot know universals because you only ever see particulars. All forms of realism I have thus encountered involve a balance between empiricism and rationalism. Realism accepts the existence of universals and the necessity of generating them from both experience of particulars and a rationale process of fitting the particulars into a set of existing knowledge and generating new knowledge.

Nominalism (which follows from a strong (extreme) empiricism) is the belief that there are only particulars. But realism is not the belief that there are only universals. Which may be one reason I accept realism, and do not consider myself a nominalist (anyone that believes we can get general knowledge from research and that those results have a chance at being true beyond the particular data collected in that study is not a nominalist since you believe in universals). No need to get into the philosophical traditions that propose the only thing that exist are universals……

As I think about a knowledge based practice I am struck by the importance of recognizing particulars and universals (realism).

When I consider results from a systematic review to apply to a patient, I am accepting the universal. But, when I conclude that these results do not apply to a particular patient, am I being a nominalist, am I rejecting the existence of the universal? No. But only if I have a reason for why the results do not apply. If I conclude that the results do not apply simply because the patient is particular and does not share anything in common with the study subjects without reasons, just because the patient was not in the study, then I am being a nominalist (at least a functional nominalist). (Note, when I use the term “functional…..x” I am simply pointing out that sometimes we may not act as if we believed something without actually being meta-cognitively aware of that belief).

Much of a knowledge based practice needs to address the universals vs. the particulars. We will never be treating someone that was in the study that was used in the review that was used in the clinical practice guideline, but that is ok so long as we are applying universals and that those universals apply well to the patient at hand. But, when there are reasonable particulars those need to be identified and considered. We need to keep in mind which particulars are deal breakers, and which merely change the probability or slightly alter our belief. All of these activities seem to require a realist approach (since we do accept universals), and a balance between empiricism and rationalism (dare we say a critical balance of experience and mind).

Finally, I am not aware of anyone in EBP out there arguing a case for a strong empiricism or for the nominalism which follows from it. While these tend to go together philosophically, nominalism is completely disruptive to the aims of EBP. Why then am I having this self imposed dialectic? Because I sometimes sense a “functional strong empiricism” in the language and practices of EBP. We need to be aware of such language and practices - such as limitations imposed in practice guidelines to only use RCT based systematic reviews as evidence; or a hierarchy of evidence which gives such strong preference to experiential observations over mechanistic explanations.

Soon I will have to post some thoughts about the opposite extreme - extreme rationalism - - and the insistence that our knowledge of mechanisms based purely on a rationale process and no actual empirical observations is equally (perhaps more) damaging to practice….

Leave a Comment