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  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>What is Abstraction in Biomimetics?⋆</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Ludger Jansen</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>PTH Brixen College</institution>
          ,
          <addr-line>Piazza Seminario 4, 39042 Bressanone</addr-line>
          ,
          <country country="IT">Italia</country>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>University of Rostock, Institute of Philosophy</institution>
          ,
          <addr-line>18051 Rostock</addr-line>
          ,
          <country country="DE">Germany</country>
        </aff>
      </contrib-group>
      <fpage>0000</fpage>
      <lpage>0002</lpage>
      <kwd-group>
        <kwd>biomimetics</kwd>
        <kwd>cognition</kwd>
        <kwd>methodology</kwd>
        <kwd>abstraction</kwd>
        <kwd>concretisation</kwd>
        <kwd>heuristics</kwd>
        <kwd>models</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>1. Introduction</title>
      <p>
        Biomimetics is a field of research that tries to learn from nature to develop improved technical
solutions. More specifically, biomimetics is said to be the “interdisciplinary cooperation
between biology and technology or other innovative fields in order to solve practical problems
through the functional analysis of biological systems, their abstraction into models and the
transfer and application of these models to the solution”
        <xref ref-type="bibr" rid="ref1">(ISO 18458:2015, p. 2, emphasis in the
original [1])</xref>
        . It is, therefore, generally acknowledged that abstraction plays an important part
in biomimetics. There is also a consensus that the abstraction starts from some biological entity,
here called a “biological system”, which is often an organism, but can also be a part, trait or
behaviour of an organism, a biological process like evolution, a plurality of organisms like a
swarm of birds or a school of fish, or artefacts or products of animals like nests, eggs or spider
silk. It is less clear, however, what exactly abstraction is and how it works, and what the product
of abstraction (here called “model”) actually consists in.
      </p>
      <p>This paper surveys various statements on abstraction from the biomimetic literature and
suggests a reconstruction of the respective cognitive processes and their underlying ontological
structure. I argue that abstraction in biomimetics is close to the traditional understanding of
statements about abstraction in biomimetic guidelines (section 2) as well as in descriptions of
the biomimetic research process in the biomimetic literature (section 3). I will then discuss how
my suggestion relates to the findings in the literature (section 4). Section 5 concludes the paper.</p>
    </sec>
    <sec id="sec-2">
      <title>2. Abstraction in the VDI guidelines</title>
      <p>As a research area with a heavy technical orientation, biomimetics often refers to guidelines
and norms developed by such institutions as the International Standardisation Organisation
(ISO) or the Association of German Engineers (Verein Deutscher Ingenieure, VDI). In fact, the
VDI pioneered the production of guidelines in the field and prepared the path for the ISO [2][3].
The VDI guideline VDI 6220-1, on the conception of biomimetics and its strategies, originally
published in 2012, has been updated in 2021 and a second part, VDI 6220-2 on the biomimetic
development process, has been added in 2023 [4][5][6].</p>
      <p>VDI 6220-1 (2021) adapts the definition of biomimetics given in ISO 18458 (quoted above)
that puts the “abstraction into models” centre-stage, where these models are derived “through
the functional morphological analysis of biological systems” and “the transfer into and
application of these models to the solution (p. 5). Like its predecessor, VDI 6220-1 (2012), it
defines abstraction as an “inductive process in which a general conclusion is drawn based on
the observation of a specific object” (p. 4). This is strange, as such generalising inferences are
standardly called “induction” in logic. An inductive reasoning process could, e.g., lead from
“This swan is white” to “All swans are white” – i.e., from the observation that one instance (or
more) of a certain kind has a certain property to the conclusion that all instances of a certain
kind have this property. Another variant would lead, e.g., from “Swans can fly” to “Birds can
fly” – i.e., from the statement that a certain property applies to a species to the statement that
this property also applies to a genus of this species. Neither of these two variants would
probably be considered an abstraction. It goes without saying that such inductions are
important but not deductively valid and theoretically difficult to justify, as black swans and
penguins show for the two examples mentioned here. Alternatively, one could consider
nonstandard ways of induction that do not infer universal statements but generic statements like
“Typically, birds can fly”. Such a result would allow for atypical exception cases. But this is also
not the intended product of abstraction processes in biomimetics, where the result of
abstraction processes are rather new descriptions of the design problem or a description of the
design solution.</p>
      <p>In a note to the definition of abstraction, VDI 6220-1 (2012) and ISO 18458:2015 add: “In
biomimetics, this conclusion is ideally a physical context for describing the underlying
functional and operating principles of the biological model.” VDI 6220-1 (2021) echoes a variant
of this: “In biomimetics, this conclusion is ideally a physical context for describing the
underlying form–function relationships and operating principles of the biological system.” This
is verbally repeated in VDI 6220-2. Taken at face value, both variants commit the same category
mistake, as conclusions of inference steps are propositions, which may be about physical
contexts but not identical to them.</p>
      <p>Describing abstraction as a variant of generalisation does also not fit well to the idea that
abstraction is a process that leads to a model. A model is defined by VDI 6220-1 (2021) as a
“coherent and usable abstraction originating from observations of biological systems” (p. 6; no
such definition in the 2012 version). Standardly, the guideline distinguishes two variants of
biomimetic research and development projects, which are labelled “technology pull” and
“biology push”, respectively. A “technology pull” project starts from a technological problem
and looks for a biological solution that can help to realise that function. In contrast, a “biology
push” project starts from a biological observation and tries to implement this in a market-viable
product. The biomimetic process “goes through several abstraction steps and modifications”
(p. 7), and it is not complete “without performing a systematic analysis, abstracting, or
transferring an operating principle” (p. 8). The biomimetic development process is characterised
as consisting of three steps – also referred to as the “three A” (p. 13):
•
•
•</p>
      <p>First step: “A shape–function analysis of a biological system is carried out (analysis)”.
Second step: “The biological system is abstracted to a model (abstraction)”.</p>
      <p>Third step: “The model is transferred and applied to develop a solution or product
(application)” (p. 9).</p>
      <p>Abstraction is said to be “of great importance”, because “biological systems are generally
highly complex” (p. 15). Abstraction always starts with the “biological model”, i.e., an organism
or some part or behaviour pattern of it; the abstraction phase will then lead to “explanatory
approaches in the form of form–function relationships” (p. 18).</p>
      <p>The conceptual framework of VDI 6220-2 is based, to a large extent, on VDI 6220-1 (2021).
Indeed, VDI 6220-2 (2023) only slightly deviates from VDI 6220-1 (2021) when defining
abstraction as a “process in which a generalised conclusion is drawn from the observation of a
specific object”. For sure, the words “abstract” and “abstractions” are used (and sometimes
misused) in multiple senses (just compare the usage of these words in modern art and set theory,
where it refers to constituting a set by means of a predicate). Consequently, but somewhat
clumsily, VDI 6220-2 goes on to make explicit the process–product ambiguity of the word
“abstraction” (“This also includes the result of this process”). In fact, like “observation”,
“explanation” or “perception” and other words ending in “-tion”, “abstraction” can refer to both
a certain cognitive process and the result of this cognitive process. To the surprise of the reader,
another note to the definition quoted above reports on the classical philosophical sense of
abstraction: “‘Abstraction’ is also referred to as the mental removal of some features or
properties of an object or system that are not relevant to the aspects of its behaviour under
investigation.” (p. 3)</p>
      <p>VDI 6220-2 (2023) describes the biomimetic development process by means of the so-called
“biomimetic spiral” (p. 8). In this process description, “analysis”, “abstraction” and “application”,
the three phases already mentioned in VDI 6220-1, are supplemented by a preceding
“arrangement” phase (“Aufbereitung”). Abstraction is identified as an important step for both
variants, “biological push” and “technology pull”. The goal of a “technology pull” development
process is described as “abstracted effect principles” (p. 8). This is reached in the “abstraction
phase” through “an understanding necessary for the technical implementation […] for the
selected biological solution principle”, which is reached through “an abstraction process” (p. 9),
in which “the individual effect principles for the desired function are worked out in detail,
starting with a literature search and, if possible/necessary, through detailed biological
investigations”; the result is finally “transferred from biology to technology through a further
translation step”, e.g., through the construction of demonstrators (p. 10) – i.e., 3D-models that
show that the hypothesised structure of effect principles (sometimes also called “working
principles”) does, in fact, lead to the intended behaviour of the system.</p>
      <p>In contrast, in a “biology-push” process, the abstraction phase aims at finding “an application
in technology”. Later, an “abstraction in principle” is said to be necessary, in which “[t]he
solution principle is described by means of models” (p.12). When “abstracting and thus
detaching the biological principle from its initial context”, the biomimetic researcher is advised
to consider the “different preconditions and adaptations” prevailing in biological systems
(p. 13).</p>
    </sec>
    <sec id="sec-3">
      <title>3. Abstraction in the biomimetic literature</title>
      <p>To shed further light on these unequal findings, I will now look at three descriptions of the
abstraction process from the biomimetic literature, in particular at the accounts of Werner
Nachtigall (subsection 3.1), Kristina Wanieck (subsection 3.2), and Manfred Drack and
colleagues (subsection 3.3).</p>
      <sec id="sec-3-1">
        <title>3.1. Nachtigall</title>
        <p>Werner Nachtigall is probably the most prolific author of books on biomimetics in the
Germanspeaking world. From a meta-theoretical perspective, his book on “Biomimetics as Science” [7]
is probably the most important one (all translations are mine). Already in the subtitle of his
book, Nachtigall makes it clear that he sees abstraction (“Abstrahieren”) as a constitutive step
of the biomimetic research process. This step consists in the “abstraction of general principles
from ‘original data from biology’” (“Abstraktion allgemeiner Prinzipien aus den ‘biologischen
Originaldaten’”), and it is these “abstracted principles of nature” (“abstrahierte
Naturprinzipien”, vii), which will then be used in the technical setting (vii). Sometimes
Nachtigall simply talks about “Prinzipabstraktion” (e.g., 72). These principles are thought of as
being real elements of nature, out there to be discovered by biologists, to be explained in
theoretical terms and then to be transferred to the domain of engineering.</p>
        <p>Nachtigall dedicates the whole part B of his book to abstraction from biological findings and
the discussion of general principles. For him, the crucial point in abstracting such a general
principle from nature is the construction of a model (p. 79); the model is then called a
“prinzipienabstrahierendes Modell” (p. 80) or “modellhafte Prinzipabstraktion” (p. 85). The
process is sometimes called “Modellabstraktion” (p. 84), but this whole terminology is never
explicitly introduced and very variegated. The next steps in the biomimetic research process
lead from the “abstracted, still biological model” to a “technically abstracted, already technical
model” (p. 87). According to Nachtigall, the step from the biological data and the abstracted
model is mediated by analogy (p. 96). Nachtigall quotes Zoglauer [8] who sees a model as
“simplification and abstraction of an original” (“Vereinfachung und Abstraktion eines
Originals”, p. 98). While being constitutive of models, abstractions can also contribute to the
limitations of models (p. 100). Nachtigall goes on to define models (in the context of
biomimetics, that is) as “simplifying abstractions of biological substrates, i.e., of structures or
functions or the connections of structures with functions”; more concisely, he says that a model
is “the analogical abstraction of an original” (p. 105). He also talks about the “abstraction of a
biological species by way of generalising induction” (“Abstraktion einer biologischen Art durch
generalisierende Induktion”; p. 42, Fig. 4.7).</p>
        <p>Next to the models of principles, which show how something works, Nachtigall also speaks
about functional models (“Funktionsmodell”, p. 109) and, as a subkind of these, cybernetic
models (“kybernetische Modelle”, p. 113). Nachtigall implicitly admits of degrees of abstraction
when he talks about “half-abstract” things (“das halbabstrakte Schaubild”, p. 19), and he also
mentions “levels of abstractions” (“Abstraktionsebenen”, p. 179), possibly referring to structures
and functions as possible objects of abstraction.</p>
        <p>In Nachtigall’s picture, abstraction is supplemented by the reverse process of concretisation
(“Konkretisierung einer Vorstellung”), which yields “a concrete instead of an abstract basis of
deduction” (p. 106). But this term is only very rarely used and never explicitly introduced (the
only other occurrences being “technisch konkretisiert”, p. 185, and
“Konkretisierungsverfahren”, p. 190).</p>
      </sec>
      <sec id="sec-3-2">
        <title>3.2. Wanieck</title>
        <p>Wanieck’s introductory textbook [9][10] contains a detailed description of the biomimetic
development process with interesting details with respect to abstraction. In particular, she
stresses that “the degree of abstraction varies” ([10], p. 9). She distinguishes three “level[s] of
abstraction of biological knowledge” and claims that “[w]ith an increasing level of abstraction,
the proximity to the natural model decreases, but the potential for application increases” (Figure
2.1 on p. 9 and other places; see my Table 1).</p>
        <p>In the case of the Velcro® tape (“hook and loop fasteners inspired by burrs”), she says that
the abstraction level is “low”, because “the similarity to the natural model is high and the
application potential ranges in the context of the connection of two surfaces or objects – in
nature and in technology” (p. 9). In the case of the Lotus effect (“self-cleaning properties of the
Lotus plant”), she diagnoses “a higher level of abstraction”, which “means that the closeness to
the natural model is lower than with Velcro fasteners, as the structures of the lotus surface are
no longer emulated 1:1” (p. 10). It is not clear, however, whether this comparison to the Velcro
case is really accurate. For sure, the structures transferred in the Lotus case are much smaller
and not visible to the naked eye, but also in the case of the Velcro fasteners, the form of the
hooks and loops is not simply copied from the biological paradigm, but adapted to the technical
context in which it is then used.</p>
        <p>Finally, at “abstraction level three, knowledge about biological systems is abstracted to
general innovative principles, which primarily serve the generation of ideas”. As an example,
she again refers to “the phenomenon of surface structuring known from the lotus plant”, which
“can also be understood as an innovative principle that can be applied in various areas”,
allowing “new functions to be integrated into products that are not directly related to the
cleanability of surfaces, but rather serve, for example, to improve haptics, coloring, or
transferring information” (p. 10).</p>
        <p>Wanieck’s description of the three levels insinuates the idea that abstraction comes in
degrees. On the other hand, the descriptions of the three levels rather pick out different aspects
that could be abstracted from a given biological paradigm. Her first level, the form–function
analysis, seems to focus on those aspects studied by morphology (from Greek morphê, form)
and their connections to functions. The second level concerns an analysis in terms of physical
or chemical laws, which might come with a certain reductionist impetus. The third level, finally,
is about more general (and more vague) strategies the engineer could pursuit to find new
solutions, which still leaves a lot of questions open to be answered. Inspired by the Lotus leaf
or other biological phenomena, structuring a surface might be a helpful hint, but then there is
still the question how to structure it.</p>
        <p>Wanieck describes biomimetics as a process consisting of eight steps ([10], p. 19–27). In two
of these, she sees abstraction at work; these are “problem abstraction” (step 2) and “abstraction
from biology” (step 6). The purpose of problem abstraction is to turn the “solution-neutral
problem description”, or the “targeted solution described as a function” (p. 20) found in the first
step into an “abstract description of the problem that can be transferred to biology” (p. 24). This
is needed because “technical terms are not suitable 1:1 for searching in biology”, and “the
problem or objective function1 must be formulated in such a way that biological models can be
searched for”; again, “different levels of abstraction and functions” can be chosen to process this
step. As tools to support this step, Wanieck suggests using the Biomimicry Taxonomy2 and the
association list described by Gramann [11].</p>
        <p>The second abstraction step is “abstraction of biology” (p. 26) or, more appropriately,
“abstraction of biological findings” (p. 31). In this step, “biological functions are translated into
the technical context”; this results in a “description of the biological phenomenon as a physical–
chemical functional principle”, in which “the biological principle is detached from the biological
model and broken down to a physical–chemical function”, such that “the principle can be made
usable for a technical application” without the biological model itself becoming part of the
solution in technology (p. 26). As there is “no general approach” to be followed for this step,
Wanieck warns that “the work of abstraction requires time and expertise”; she advises
biomimetic developers “to describe functions in the biological system by the main components
of energy, material, and information flow”, or to “ask in general terms what is responsible for
the observed function”, where the answer should be expected “at different levels of scale”, and
to search support from a biologist (p. 26).</p>
      </sec>
      <sec id="sec-3-3">
        <title>3.3. Drack et al.</title>
        <p>Following the lead of the VDI guidelines and authors like Nachtigall, Drack et al. [12] agree that
abstraction is an essential process in biomimetic research. Following their description,
biomimetics proceeds by abstracting functions and working principles from biological models,
1 In the German version [9], p. 22: “zu erreichende Zielfunktion”.
2 Cf. https://www.asknature.org/resource/biomimicry-taxonomy. In the older German version of the book ([9], p.
24), Wanieck also refers to the “BIOlogy Inspired Problem Solving” (BIOPS®) online dictionary, which, however, has
since disappeared from the internet.
transferring them to the engineering domain and, subsequently, integrating them into
constructions and, finally, market-viable products. In particular, Drack et al. write:
•
•
•
•
“Engineers are typically challenged by a task which they attempt to solve by some manner
of construction. In a typical textbook case, the workflow leads from the abstract level to
ever more tangible solutions. Accordingly, this work flow encompasses the successive
levels of: (1) task, (2) function, (3) working principle, (4) construction, and finally (5) the
overarching system.” (p. 2)
“The overarching system and the construction in the biological model show many features
that are typically not transferred. For instance, the material or the particular shape of the
bur […] are not used in Velcro®. Rather, they are abstracted.” (p. 5)
“As research progresses, more and more features that are found to be irrelevant for the
particular goal are left aside. Correspondingly, the complexity of the investigated item
decreases and the degree of abstraction increases […]. The specific boundary conditions
(e.g. particular shapes and material properties) in the biological system are successively
abstracted and the inherent functions and working principles become exposed.” (p. 7;
omitted from the quote is a reference to a definition of abstraction from Psillos [13] that is
quoted below)
“Note that the levels of function and working principle do not involve particular sets of
parameters—material, geometrical or otherwise. Later along the time line, during the
application phase, ever more detailed engineering images are produced. Graphical
representations can be understood as a continuous chain reflecting the degrees of
complexity and abstraction along the biomimetic process.” (p. 9)</p>
        <p>According to the picture emerging from these quotes, the biomimetic research process steers
through different stages of, first, increasing abstractness in order to abstract functions and
working principles, followed by stages of decreasing abstractness in the construction process
proper (cf. their Fig. 3 on p. 7). This seems to be exactly abstraction in the sense of disregarding
detail, or, in the words of note 2 of VDI 6220-2 (2023), “the mental removal of some features or
properties of an object or system that are not relevant to the aspects of its behaviour under
investigation”. This understanding of abstraction can be corroborated by referral to the
understanding of abstraction in other areas. In a forthcoming glossary of biomimetic terms,
Drack et al. list several definitions of abstraction both in general language and in relevant
domains, like philosophy of science, engineering and architecture [14]. These definitions all
converge on the central point that abstraction should be thought of as a process of excluding
properties or other details:
•
•</p>
        <p>Oxford English Dictionary (out of a list of seven possible meanings): “The action of
considering something in the abstract, independently of its associations or attributes; the
process of isolating properties or characteristics common to a number of diverse objects,
events, etc., without reference to the peculiar properties of particular examples or
instances.” [15]
Philosophy of science: “The removal, in thought, of some characteristics or features or
properties of an object or a system that are not relevant to the aspects of its behaviour under
study.” (Psillos [13])
•
•</p>
        <p>Engineering: “Ignoring what is particular or incidental and emphasizing what is general
and essential.” (Pahl et al. [16])
Architecture: “Omission or severe simplification of details in drawings of a building or
landscape leaving essentials of massing, form, and solids, so that the basis of a design can
be explained.” (Curl [17])
Inspired by Nachtigall’s use of the term, Drack and Jansen [18] adopt the term “concretisation”
in order to describe the inverse process of adding detail, which is important for both engineering
in general and biomimetics in particular.</p>
      </sec>
    </sec>
    <sec id="sec-4">
      <title>4. Discussion</title>
      <p>This review of a small selection of the biomimetic literature shows a consensus that abstraction
is central to the biomimetic research process. As it turned out, however, there is no consensus
about what exactly abstraction is in the context of biomimetics. It seems clear, though, as the
VDI 6220-2 notes, that “abstraction” can both refer to a process and its product. As a process,
abstraction starts from something and ends at a certain result:
•
•
•</p>
      <p>As to the starting point, there is consensus that is in the domain of biology; it is the
“biological model”, an organism or a certain part of it or a behaviour pattern that it displays
(or a product of such behaviour).</p>
      <p>The result, or product, of the abstraction process is called “model”, “principle”, or “function”
and “operating principle” or “efficient principle” in different texts.</p>
      <p>The process itself is characterised as a cognitive process; it is sometimes described as a
generalization and sometimes as disregarding unnecessary detail.</p>
      <p>The findings regarding the endpoint of the abstraction process suggest that, in fact, the
characterisation of the abstraction process as a process of disregarding unnecessary detail is
fundamental. Conversely, the abstraction process could also be described as focussing on the
relevant details. If the abstraction process starts from a finite set of information, both
descriptions might be equivalent. Both the process of disregarding certain aspects and the
process of focussing on certain aspects yield smaller sets of information. Still, it might be
psychologically more adequate to say that researcher focus on the relevant aspects instead of
thinking of the irrelevant aspects that they are irrelevant and can be disregarded. However, if
the starting point is an infinite set of information, like the set of potential information to be
gained about a concrete material object like an organism, the results of focussing and
disregarding are clearly different: Disregarding finitely many aspects from an infinite set of
information still leaves one with an infinite set of information, while focussing on finitely many
aspects from these infinite set of information clearly yields a finite set of information (see
Table 2). Focussing on relevant detail is thus an even more accurate description of what is going
on in abstraction processes.</p>
      <p>This understanding of abstraction fits well to the ontological characterisation of functions
and operating principles as abstract properties that are borne by the concrete organisms that
biomimetic researchers analyse – but are then cognitively isolated from their bearers and
abstractly described and analysed. This understanding also fits to the claim in many texts that
the objects of thought or research can be more or less abstract. As we can ignore more or less
properties, the abstract and the concrete will constitute a range of more or less abstract or
concrete models, which are bounded on the side of the concrete by the concreteness of the
actual material objects, be they biological or technical, in the actual world. Ignoring unnecessary
details can happen in at least four ways which follow distinct ontological patterns:
•
•
•
•</p>
      <p>Specificity. If an entity can be correctly described by a term T, it can be correctly described
by any hypernym of T. The higher up the species–genus hierarchy the hypernym is located,
the less informative the description will be.</p>
      <p>Granularity. An entity can be partitioned in more or less detailed granular partitions [19].
An organism can be described as an organism among other organisms, as a complex of
organs, as a complex of molecules, as a complex of atoms, or as a complex of sub-atomic
particles. Approximatively, it could be said that the coarser the partition, the less detailed
the description is.</p>
      <p>Variabilisation. Given a property of a certain kind, we can disregard which specific
property this is and use the description of the kind only. E.g., instead of ascribing the
determinate colour purple, we can ascribe the less determinate colour red, or the
determinable property coloured, i.e., say that there is some colour but we do not say which
one.</p>
      <p>Entirely disregarding certain properties. If an entity can be correctly described as
having all of a set of properties ℙ, it can also be correctly described as having any subset of
ℙ. This, again, goes along with a lack of information.</p>
      <p>In addition, one might think of means–end hierarchies, causal chains or hierarchies of
constitution levels as possible dimensions of ‘abstraction’. However, with any of these it is not
as clear whether switching between levels in these hierarchies goes along with restricting
oneself to less information; one rather deals with different pieces of information on different
levels in these hierarchies.</p>
      <p>Loss of information is not necessarily a bad thing, because, as Drack et al. [12] point out, an
increase of abstractness comes along with a decrease of complexity, which may be very
welcome in a research context, as long as all relevant information is covered. Wanieck’s
distinction of three levels of abstraction which I describe above (Table 1) seems in part to reflect
different levels of granularity: The form–function aspect can mostly be found at the granular
level of body parts of organisms, while physico-chemical principles could be localized at the
molecular or sub-molecular level. However, physical principles, like the law of the lever, would
also be situated at the mesoscopic level. Even more difficult is it to integrate the suggested third
abstraction level (abstracting an “innovative principle”) into the granularity logic. Rather, it
disregards a lot of detail if, instead of copying the specific surface structure of the lotus leaf one
thinks of structuring surfaces in general. Thus, Wanieck’s levels are also compatible with
viewing abstraction as disregarding detail or focussing on relevant detail.</p>
      <p>Moreover, while it contradicts the official definition of abstraction given in the VDI
guidelines, seeing abstraction as disregarding unimportant detail fits nicely to an example
mentioned by the VDI 6220-2 (2023), namely the eNandu project ([6], p. 23–24). This project
applied the so-called template-and-anchor approach (see Figure 1). An early publication
describing the template-and-anchor approach explicitly describes the template as “the simplest
model (least number of variables and parameters) that exhibits a targeted behavior” ([20], p.
3325). As the case in question in this publication is “legged motion on land”, the template is said
to be “a model created by ‘trimming away’ all the incidental complexity of joints, muscles and
neurons”, while the anchor is described as “a more realistic model fixed firmly or grounded in
the morphology and physiology of an animal”, which is not only “more elaborate”, but “must
have embedded within it the behavior of its templates” (ibid.). The various stages of the
development of the eNandu (depicted in an idealised manner in Figure 1) mirror these cognitive
steps: From the concrete and complex biological model (called an “embodiment”), the nandu, an
anchor model is abstracted that describes the mechanism of nandu movement. The anchor
model is then transformed into an even more abstract – i.e., less detailed – model, the template.
In the terms of Drack et al., the template is the “pivot” ([12], p. 7 and Figure 7 on p. 8) that is
the culmination of the biological research into the motion process of the nandu (and other
species), and the starting point of the engineering design process. During this process, the
template is again enriched by adding more specifications via a technical anchor model to the
design or construction plan, from which finally the concrete technical embodiment is produced.</p>
      <p>Finally, we can also explain why some biomimetic researchers (like the authors of the VDI
guidelines) may think that abstractions are generalisations. For sure, the development steps in
the eNandu development are not well described as inferences from “This F is G” to “All Fs are
Gs”, or to “Typical Fs are Gs”. Removing and adding detail is a much better description of what
happens here. A possible motivation for why the VDI guidelines nevertheless think of
abstraction as generalisations might be that models with fewer specifications may fit more
cases. In the eNandu case, e.g., the template model fits both to the biological and the technical
embodiment, while the more detailed technical anchor model fits to the technical embodiment
only (i.e., to the eNandu) and not to the biological embodiment (the nandu). That less detail
comes with wider applicability is, however, at best a rule of thumb. It is not at all necessary. If
a model already fits to all cases in question, eliminating even more features will not lead to a
model fitting more cases. Also, the elimination of features from the model can come with loss
of explanatory and predictive power. Hence, there will be trade-offs between generality and
usefulness of models. Biomimetic research will aim at models that are abstract enough to be
understandable for researchers and transferable to the technical domain. But of course, the
models need to be concrete enough to have the desired explanatory power, that then translate
into the desired causal capability within the technical embodiment.</p>
    </sec>
    <sec id="sec-5">
      <title>5. Conclusion</title>
      <p>I have shown that while there is a large consensus in the biomimetic literature that abstraction
is a crucial element to the biomimetic research process, there is no consensus, and maybe not
even a clear understanding, of what abstraction is in the biomimetic research process. As I have
shown, the understanding of abstraction varies from understanding it as a kind of generalisation
to the more traditional account of disregarding irrelevant detail. I have shown how this
traditional understanding, and more accurately its converse description as focussing on relevant
detail, fits well to the role ascribed to abstraction in the biomimetic literature, and to what is
supposed to happen in the abstraction steps in biomimetic research projects. Self-descriptions
of engineers sometimes lack clarity and rigour (for an analysis of one example, cf. [21]). The
present study shows that this is also the case for the self-descriptions of biomimetic researchers,
which comprise both biologists (and other scientists) and engineers. An interdisciplinary
collaboration with philosophers, and maybe cognitive psychologists, can help to better
understand the biomimetic research process and its contents, and how this important cognitive
process can be adequately modelled by means of an ontology.</p>
    </sec>
    <sec id="sec-6">
      <title>Acknowledgements</title>
      <p>Research for this presentation has been funded by the German Research Foundation (DFG)
through the project “Learning from Nature: Epistemological and Ontological Foundations of
Biomimetics” (no. 492191929). I am indebted to Manfred Drack, Kristina Wanieck, Konrad
Werner and Dilek Yargan for helpful comments on previous versions of this paper, and to the
participants of CAOS@JOWO 2024 for an inspiring discussion.
[2] N. Hoeller, F. A. Salustri, Advancing biomimetic materials through ISO standards,</p>
      <p>Bioinspired, Biomimetic and Nanobiomaterials 5:4 (2016) 171–175.
[3] K. Wanieck, H. Beismann, “Perception and role of standards in the world of biomimetics”,
Bioinspired, Biomimetic and Nanobiomaterials 10:1 (2021) 8–15.
doi:10.1680/jbibn.20.00024.
[4] VDI 6220-1 (2012), Bionik: Konzeption und Strategie. Abgrenzung zwischen bionischen
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[5] VDI 6220-1 (2021), Bionik: Grundlagen, Konzeption und Strategie – Biomimetics:</p>
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Biologie und Technik, Stuttgart-Bad Cannstatt, Frommann-Holzboog 1994, 12–24.
[9] K. Wanieck, Bionik für technische Produkte und Innovation Ein Überblick für die Praxis,</p>
      <p>Springer, Wiesbaden, 2019.
[10] K. Wanieck, Biomimetics for Technical Products and Innovation. An Overview for</p>
      <p>Applications, Springer, Wiesbaden, 2022.
[11] J. Gramann, Problemmodelle und Bionik als Methode, Diss. TU München, 2004,
http://mediatum.ub.tum.de/601901.
[12] M. Drack, M. Limpinsel, G. de Bruyn, J. H. Nebelsick and O. Betz, Towards a theoretical
clarification of biomimetics using conceptual tools from engineering design, Bioinspiration
&amp; Biomimetics 13 (2018) 016007. doi:10.1088/1748-3190/aa967c.
[13] S. Psillos, Philosophy of Science A–Z, Edinburgh, Edinburgh University Press, 2007.
[14] M. Drack et al., Glossary of architectural and constructional biomimetics, Springer, Cham.</p>
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[15] OED, The Compact Edition of the Oxford English Dictionary, Oxford University Press,</p>
      <p>Oxford, 1987.
[16] G. Pahl, W. Beitz, J. Feldhusen, K. H. Grote, Engineering design: A systematic approach,</p>
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[17] J. S. Curl, A Dictionary of Architecture, Oxford University Press, Oxford, 1999.
[18] M. Drack, L. Jansen, Biomimetics Analyzed: Examples from an Epistemological and
Ontological Perspective, in: F. Meder, A. Hunt, L. Margheri, B. Mazzolai (Eds.), Biomimetic
and Biohybrid Systems. 12th International Conference, Living Machines 2023, Genoa, Italy,
July 10–13, 2023, Proceedings, Part II (LNAI 14158), Cham, Springer 2023, 273–289.
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[19] T. Bittner, B. Smith, A Theory of Granular Partitions, in: M. Duckham, M. F. Goodchild and
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