Janice Morse (2015) is quite clear what theoretical saturation is not in her recent editorial in Qualitative Health Research. It is not the accumulation of events to a point where we have heard everything there is to be heard about a matter. Theoretical saturation happens, according to Morse, at a quite different level of abstraction at a level of characteristics within categories. The theories Morse is thinking about are statements that in some way account for all the events recorded in the data. For realists this reliance on events is the limitation of theoretical saturation.
The foundation of theoretical saturation in grounded theory is data. Repeating an idea she has discussed elsewhere (Morse, 1995), Morse (2015:587) points out that ‘in qualitative enquiry, the data at the tails of the curve are equally important and must be deliberately collected until adequate’. In other words, qualitative researchers seek out what quantitative researchers might refer to as outliers. These are unusual cases that present theory discovery with paradox, uncertainty, and difficulty. Account for these in a theory and it will be a stronger more saturated theory. Buttressing this comprehensive collection of data across a putative distribution is a call to replicate data, which means ensuring ‘several participants have essential characteristics in common’ (587).
These strategies yield rich data, but for theoretical saturation to happen data must be known intimately. At the same time, the methods of grounded theory—memo writing and coding—intentionally withdraw these data from the site of their production. As Morse observes, ‘the process of coding into categories removes the experience from the individual participant and is the first step on the process of conceptualisation, synthesis, and abstraction’ (588). Theoretical saturation rests on strategies to ensure the collection of comprehensive and replicated data, and an analysis through immersion and abstraction from context.
Realist methodologists (Porter, 1993; Pawson, 2006; Maxwell, 2012) accept the notion of theoretical saturation rather uncritically. Porter (1993:599), for instance, citing Anselm Strauss (1987) contends that his research investigating racism amongst intensive care unit staff ‘continued to a point of ‘theoretical saturation”. I’m not sure it did, unless Porter means theoretical saturation in the way Morse suggests it is not—when everything there is to say about the matter is said.
Even if this definition of theoretical saturation is accepted it sits at odds with a realist methodology. The problem for realists is not that new events will be found that need bolting into the theory. This is a trivial argument. New events will always happen, the social world is dynamic and only relatively enduring. It is the nature of events that is the problem. Events are empirical accounts that may be observed, listened to, and faithfully recorded. But they are not the end of the matter in the stratified and depth ontology of a realist methodology. A claim to theoretical saturation is a claim to reify structures, the relationships that happen in particular contexts. These are expressed in some way in events and therefore in data. But in grounded theory, as Morse points out, characteristics within categories are purposefully withdrawn from the contexts of their production. This is a flat empiricist ontology. It is quite at odds with a realist explanation, which explicitly accounts for context as generative mechanisms as powers, liabilities and dispositions that shape the expression of events. Most often these are not amenable to measurement (as data). We make claims for these. They are theories, which as Joseph Maxwell (2012) contends, are as real as rocks. In grounded theory methodology theories emerge from data. In a realist methodology theories are as real as the data.
It is because of this depth of reality that theoretical saturation can never be achieved in realist research. The best we can manage is a fallible model (Ragin, 1992; Lakatos, 1976), which best brings evidence into a relationship with theory. This model will have all of the features of good research Morse lays claim to—it will account for the evidence, surprise, excite, and extend understanding and insight about a social process—but it will never saturate the matter. It awaits the next investigation, where this model will be tested, refined, and judged once more.