Abstract
This paper illuminates the explanatory role of vagueness und species membership against the background of scientific developments in recent stem cell research. With the help of the Neo-Aristotelian concept of “life form naturalism” ontologically vague entities such as stem cells, all above induced pluripotent stem cells (iPS), could be described as necessary constituents for the correct sorting and naming of natural processes and its bearers. Furthermore this specific assessment allows drawing some important ontological and ethical consequences.
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Notes
See for a contemporary rejection of mechanistic materialism drawing on a Neo-Aristotelian life-form approach: Mulders (2016).
Vagueness in rebus or ontic vagueness does not need to be incoherent or unintelligible if we articulate it in spatial or mereological terms. However, this cannot solve the problem of classificatory vagueness, but it can help to understand why there must be a mutual dependence between the vagueness of the word and the vagueness of the object in order to describe living beings or life forms.
Sortals generally tell us something about the way the world is structured, (a) how to identify essences, (b) how to count things of a kind and (c) how to indicate something as being persistent.
About the general importance of sortality for qualifying and describing entities: Sattig (2010).
The subject of vagueness has been hardly applied to questions of bioethics so far – except the question of a smooth transition from “health” to “disease” (for further details: Keil et al. 2016)—despite the fact that most of vague phenomena are situated in this area: for example, the question of the demarcation of humans and animals (in the case of cytoplasmic hybrids), the problem of distinguishing natural intervention from artificial manipulation (e.g. cognitive enhancement) and the difficulty of the assignment of certain sortals to a phase (e.g. zygote, blastomeres etc.) within the entire embryonic development process.
Before we intend to build up any taxonomy, we should always be aware of a crucial ontological gap between living organisms and non-living things: cf. Inwagen (1990).
Induced pluripotent stem cells (iPS) are generated from somatic cells (blood, skin) being reprogrammed into an embryonic-like pluripotent state. iPS enable the development of almost any type of human cell needed for medical therapies and high-level research purposes.
For a fruitful implementation of the idea that species should be viewed as life forms being able to classify organisms by something that is biologically real and explanatory useful: Sandler (2012), 6–9.
Thereby, LFN is confirming insights of common sense without developing a certain “folk biology” (for identifying LFN with a certain kind of “folk biology” see Lewens 2015, 52–55; for a general defence of accounts taking everyday knowledge seriously see Medin and Atran 1999). Neo-Aristotelian biology as a basis for LFN continues to insist on the existence of clear boundaries—a natural kind term such as “tiger” is supposed to carve nature at its joints. According to this, Aristotle holds that a natural substance “does not admit of a more and a less” (Aristotle 1963, 10). This observation corresponds to the ordinary but irrefutable statement that the fact of twilight does not mean you cannot tell night from day.
Such an axiospecies “is a biological related group of organisms that shares a life form, as described by Aristotelian categoricals.” (Crane and Sandler 2011, 300) It is worth mentioning that the general life form imposed by the Aristotelian categoricals cannot be described as a mereological sum of countable traits cultivated by species. It is more part of the qualitative sortal ontology than it is a part of a quantitative sortal ontology making the recognition of vague boundaries impossible.
In principle, an embryonic stem cell (ES) and its iPS counterpart may have, at best, the same morphological, functional, and evolutionary features (i.e. self-renewal, differentiation) while counting as differently. But if we only have in mind the molecular structure of an organism, then ES is indistinguishable from iPS, because both types are meant to belong to the same species. For this reason, the difference between ES and iPS should be assumed in their diverging causal histories.
Cluster models are often results from a mechanistic worldview working with countable lists of characteristics that cannot describe the actual liveliness of vital processes. Furthermore, they do not even give an account of necessity that could be helpful for any ethical orientation in terms of a “natural normativity” generated by teleologically structured life forms. For a typical definition of life in terms of an HPC model: Diéguez (2013).
It is quite easy to understand that stem cells as such form a heterogeneous kind. From that perspective, many scientists may use the term ‘stem cell’ in different ways (cf. Shostak 2006; Slack 2009). However, they cannot explain in which way vague boundaries are able to separate stem cells from non-stem cells. Simply to assume the existence of a certain ‘stemness’ is not feasible and tantamount to an already rejected form of strong essentialism.
Thompson cites Anscombe here: “When we call something an acorn, we look to a wider context than can be seen in the acorn itself. Oaks come from acorns, acorns come from oaks; an acorn is thus as such generative (of an oak) whether or not it does generate an oak.” (Anscombe 1981, 85) From this point of view embryonic-like stem cells (iPS) come from humans and humans can come from iPS. If we accept the wider context of an entity as a normatively relevant sphere every objection against the temporal or value-related extension of human cells must fail, because the process of generation tells us something about the “humaneness” and liveliness of a developing entity.
An iPS is not or does not represent an independent life form but is on the way to it: the iPS is sortally depending on the already developed life form. In the case of chimeras, there is no such sortal dependence, because we do not know at all to which concrete life form a certain chimera belongs.
Due to this fact artificial objects must have an uncertain functional status under the perspective of LFN. Therefore, the vital functions of an artificial entity must epistemologically differ from the vital functions of a natural entity, especially if we replace the view what is good for an organism by the view what is good as this organism.
Modern philosophy has driven a wedge between common sense and a comprehensive metaphysics following Aristotle: “[O]rdinary men live so completely within the house of the Stagyrite that whatever they see out of the windows appears to them incomprehensible and metaphysical.” (Peirce 1931, VII).
However, every axiospecies approach must be completed by a generative species concept. Mulders (2016) frankly sympathizing with LFN sees similarities between his axiospecies approach and the generative species concept introduced by Wilkins (2009). The theoretical proximity between LFN and the generative species concept does not mean that we have to agree with an overall dynamic conception of natural kinds according to which the conditions for belonging to a kind are allowed to change in time.
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Hähnel, M. Blurring nature at its boundaries. Vague phenomena in current stem cell debate. Med Health Care and Philos 20, 373–381 (2017). https://doi.org/10.1007/s11019-017-9755-4
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DOI: https://doi.org/10.1007/s11019-017-9755-4