=Paper=
{{Paper
|id=Vol-2050/foust-paper10
|storemode=property
|title=A Taxonomy of Disposition-Parthood
|pdfUrl=https://ceur-ws.org/Vol-2050/FOUST_paper_10.pdf
|volume=Vol-2050
|authors=Adrien Barton,Ludger Jansen,Jean-François Ethier
|dblpUrl=https://dblp.org/rec/conf/jowo/BartonJE17
}}
==A Taxonomy of Disposition-Parthood
==
https://ceur-ws.org/Vol-2050/FOUST_paper_10.pdf
A Taxonomy of Disposition-Parthood
Adrien BARTONa,1 Ludger JANSENb and Jean-François ETHIERa,1
a
GRIIS, Université de Sherbrooke, Québec, Canada
b
Ruhr University Bochum and University of Rostock, Germany
Abstract. We propose a taxonomy of mereological relations between dispositions,
as well as a series of axioms relating the bearers, triggers or realizations of
disposition-complexes and disposition-parts. We apply them on a use case to show
how basic dispositions can be combined to express elaborate dispositions. We
consider whether those relations of partial ordering satisfy axioms of composition
and decomposition.
Keywords. Disposition, Mereology, Causality
1. Introduction
Dispositions are realizable entities, that is, properties that can be realized by certain types
of processes, but that are present even when they are not realized [1, 2]. The Basic Formal
Ontology (BFO) defines a disposition as a realizable entity “that exists because of certain
features of the physical makeup of the independent continuant that is its bearer” ([2],
p. 178). To be realized, dispositions need to be triggered by some process: for example,
a fragile vase has a disposition to break (its realization) when undergoing a strong shock
(its trigger). Dispositions are useful to represent causal relations in BFO, as they provide
their bearers with certain causal powers. In particular, when a disposition is triggered by
t and realized by r, this implies that t causes r.
Röhl and Jansen [3] propose a formalization of dispositions for single-track
dispositions, that is, dispositions that have exactly one kind of realization given one
specific bundle of triggering events and/or background conditions. Barton and Jansen [4]
suggest first steps towards a formalization of multi-track dispositions, taking into account
that there could be several kinds of triggers as well as several kinds of realizations. For
this, they introduce a relation of parthood between dispositions. The present paper will
extend those results by distinguishing several mereological relations that can be defined
for dispositions.
In the following, terms for classes will be written in italic (e.g. “Breaking”), and
terms for instances in bold (e.g. “vase0”). A statement of the form “disposition d of b to
R when T” should be interpreted as expressing (in the vocabulary of [3]), when d is a
single-track disposition, that (1) d inheres_in b, that (2) d realized_in only R, and that
(3) d has_trigger only T. If a and b are particulars, a+b is defined as the mereological
sum of a and b. Similarly, if A and B are classes or universals, A+B is defined as the
class of mereological sums of one instance of A and one instance of B.
1
Corresponding Authors, E-mail: ethierj@gmail.com ; adrien.barton@gmail.com
We begin in section 2 by introducing three case studies illustrating different kinds
of disposition-parthood which we will axiomatize in section 3. Section 4 will
demonstrate the expressive power of the combined use of these kinds of disposition-
parthood. Section 5 discusses whether disposition-parthood relations are authentic
mereological relations and conclude.
2. Three case studies
The dispositional properties of an object and the way they are realized are often quite
complex. In order to distinguish different varieties of such complexity, we introduce
three case studies: the fragility of a vase, the solubility of a tablet, and the vulnerability
of a human to a certain kind of poison.
2.1. (Vase): Mod-part and fragility
The case study (Vase) serves as an illustration for the kind of disposition-parthood that
has been discussed in [4] under the more general label “d-part_of”. We will call it “mod-
part_of” here, in order to distinguish it from other varieties of disposition-parthood. This
case study involves the fragile vase vase0, whose fragility can be formalized as a
disposition. Three particular dispositions disp_break0, disp_crack0 and fragility0 inhere
in vase0, defined as follows:
• disp_break0 is the disposition of vase0 to Breaking when Strong_shock,
• disp_crack0 is the disposition of vase0 to Cracking when Light_shock,
• fragility0 is the disposition of vase0 to [Breaking when Strong_shock] and
[Cracking when Light_shock].
We can introduce a relation of disposition-parthood mod-part_of such that:
• disp_break0 mod-part_of fragility0
• disp_crack0 mod-part_of fragility0
We use the modifier “mod”, derived from “mode”, because fragility0 has two possible
pathways, or modes, of being realized: via disp_break0 or via disp_crack0. We will now
introduce two alternative kinds of disposition-parthood relations.
2.2. (Tablet): Add-part and solubility
The case study (Tablet) involves a medication tablet tablet0, composed of two halves
half-tablet1 and half-tablet2 – that are both part_of tablet0. Let’s introduce the
following dispositions:
• solubility0 is the disposition of tablet0 to Dissolving when Object_in_solvent,
• solubility1 is the disposition of half-tablet1 to Dissolving when
Object_in_solvent,
• solubility2 is the disposition of half-tablet2 to Dissolving when
Object_in_solvent.
We can introduce another relation of disposition-parthoood add-part_of such that:
• solubility1 add-part_of solubility0
• solubility2 add-part_of solubility0
The modifier “add” is derived from “additive”: the dissolving processes of both half-
tablet1 and half-tablet2 compose the realization of solubility0, and the triggers of the
former two compose the trigger of the latter.
2.3. (Poison): Chain-part and vulnerability
The case study (Poison) involves a person Mr. Jones vulnerable to a given kind of poison,
that causes cardiac arrest and consequently (cerebral) death. Let’s introduce the
following dispositions:
• vulnerability_heart0 is the disposition of Jones to Cardiac arrest when Poison
ingestion,
• heart_need0 is the disposition of Jones to Death when Cardiac arrest,
• vulnerability_heart_&_life0 is the disposition of Jones to Cardiac arrest +
Death when participating in an instance of Poison ingestion.
We introduce another relation of disposition-parthoood chain-part_of such that:
• vulnerability_heart0 chain-part_of vulnerability_heart_&_life0
• heart_need0 chain-part_of vulnerability_heart_&_life0
We use the modifier “chain” because the realization of vulnerability_heart0 triggers
heart_need0, thus creating a causal chain.
3. Axiomatization
As will become clear later, the relations add-part_of and chain-part_of share several
commonalities. Thus, we introduce a relation aggreg-part_of, of which both are
subrelations. We also introduce a general relation of dispositional-parthood noted disp-
part_of, of which mod-part_of and aggreg-part_of are subrelations. All these relations
are subrelations of the general part_of relation, which is axiomatized in the Relation
Ontology [5] (cf. Table 1).
part_of
disp-part_of
mod-part_of
aggreg-part_of
add-part_of
chain-part_of
Table 1: Taxonomy of parthood relations
The respective relations of proper parthood will be denoted by adding “proper_” in the
name – e.g., proper_mod-part_of. We define a disp-complex (resp. mod-complex,
aggreg-complex, etc.) as a disposition that has some proper disp-part (resp. mod-part,
aggreg-part, etc.). I.e., for “[x]”=“disp”, “mod”, “aggreg”, “add” or “chain”:
d0 instance_of [x]-complex :Û ($d, d proper_[x]-part_of d0)
3.1. Bearer and disp-part_of
The bearer of a disp-part is a (proper or improper) part of the bearer of the disp-complex:
(DISP-BEARER)
d1 disp-part_of d0 Þ [(d0 inheres_in b0 Ù d1 inheres_in b1) Þ b1 part_of b0]
In (Tablet), the bearer of solubility1 (resp. solubility2) is half-tablet1 (resp. half-tablet2),
which is a part of tablet0. In (Vase), the bearers of fragility0, disp_crack0 and
disp_break0 are the same, namely vase0. Similarly, in (Poison), the bearers of
vulnerability_heart0, heart_need0, and vulnerability_heart_&_life0 are the same,
namely Jones. However, we will see later in section 4.2 with the domino case study that
the bearer of a mod-part (resp. chain-part) is not always identical to the bearer of a mod-
complex (resp. chain-complex).
3.2. Realization and disp-part_of
We will now turn to the axioms concerning the realization of a disp-complex. In the
general case, if a disp-complex is realized in a process, then at least one of its proper
disp-parts is realized in a part of this process:
(DISP-REALIZATION)
(d0 instance_of Disp-complex Ù d0 realized_in r0) Þ
($d1, $r1, d1 proper_disp-part_of d0 Ù r1 part_of r0 Ù d1 realized_in r1)
As we will now see, both mod-part_of and aggreg-part_of satisfy more specific axioms.
A mod-complex is realized in a process if and only if at least one of its mod-parts is
realized in this very same process:
(MOD-REALIZATION)
(d0 instance_of Mod-complex Ù d0 realized_in r0) Û
($d1, d1 proper_mod-part_of d0 Ù d1 realized_in r0)
In (Vase), fragility0 is realized in a process (instance of Cracking or Breaking) if and
only if either disp_crack0 or disp_break0 is realized in this process. Things are different
for aggreg-parthood. If an aggreg-complex is realized in a process, then all its aggreg-
parts are realized in a part of this process:
(AGGREG-REALIZATION)
(d0 instance_of Aggreg-complex Ù d0 realized_in r0) Þ
["d1, d1 proper_aggreg-part_of d0 Þ ($r1, d1 realized_in r1 Ù r1 part_of r0)]
In (Tablet), if solubility0 is realized in dissolving0, its aggreg-parts solubility1 and
solubility2 are both realized, respectively in dissolving1 and dissolving2 (that are both
parts of dissolving0). In (Poison), if vulnerability_heart_life0 is realized in
cardiac_arrest0+death0, its aggreg-parts vulnerability_heart0 and heart_need0 are
both realized, respectively in cardiac_arrest0 and death0.
Note however that if an aggreg-part is realized, this does not imply anything for the
realization of the aggreg-complex. For example, if half-tablet1 dissolves, this does not
imply the dissolving of tablet0 – as half-tablet2 may not dissolve (in case it is not put
into a solvent). Similarly, in (Poison), Jones might undergo some cardiac arrest which is
not due to the ingestion of poison, in which case heart_need0 will be realized without
vulnerability_heart_&_life0 being realized (because it was not triggered by any
ingestion of poison).
3.3. Trigger and disp-part_of
We will now turn to the axioms concerning the triggers of a disp-complex. In general,
if a disp-complex is triggered, then at least one of its proper disp-parts is triggered.
(DISP-TRIGGER)
(d0 instance_of Disp-complex Ù d0 has_trigger t0) Þ
($d1, $t1, d1 proper_disp-part_of d0 Ù d1 has_trigger t1)
Again, both mod-part_of and aggreg-part_of satisfy more specific axioms. A mod-
complex is triggered by a process if and only if at least one of its mod-parts is triggered
by this very process:
(MOD-TRIGGER)
(d0 instance_of Mod-complex Ù d0 has_trigger t0) Û
($d1, d1 proper_mod-part_of d0 Ù d1 has_trigger t0)
In (Vase), fragility0 is triggered by a process (an instance of Light shock or Strong shock)
if and only if either disp_crack0 or disp_break0 is triggered by this process. However,
if an aggreg-complex is triggered, then all its aggreg-parts are triggered:
(AGGREG-TRIGGER)
(d0 instance_of Aggreg-complex Ù d0 has_trigger t0) Þ
["d1, d1 proper_aggreg-part_of d0 Þ ($t1, d1 has_trigger t1)]
In (Poison), if vulnerability_heart_&_life0 is triggered by ingestion_poison0, its
aggreg-parts vulnerability_heart0 and heart_need0 are both triggered, respectively by
ingestion_poison0 and the cardiac_arrest0 that followed. More specifically, if an add-
complex is triggered by a process, then any of its add-parts is triggered by a part of this
process:
(ADD-TRIGGER)
(d0 instance_of Add-complex Ù d0 has_trigger t0) Þ
["d1, d1 proper_add-part_of d0 Þ ($t1, d1 has_trigger t1 Ù t1 part_of t0)]
In (Tablet), if solubility0 is triggered by tablet0_in_solvent, its add-parts solubility1 and
solubility2 are both triggered, respectively by the processes half-tablet1_in_solvent and
half-tablet2_in_solvent (that are both parts of the process tablet0_in_solvent).
Note that replacing add-part_of by chain-part_of in the axiom (ADD-TRIGGER)
does not lead to a true statement: as a matter of fact, when vulnerability_heart_&_life0
is triggered by poison_ingestion0, the disposition heart_need0 is triggered by
cardiac_arrest0, which is not a part of poison_ingestion0.
However, on top of (AGGREG-TRIGGER), we can state that the trigger of a chain-
complex is the trigger of one of its chain-parts:
(CHAIN-TRIGGER)
(d0 instance_of Chain-complex Ù d0 has_trigger t0) Þ
($d1, d1 proper_chain-part_of d0 Ù d1 has_trigger t0)
In (Poison), the trigger of vulnerability_heart_&_life0 is poison_ingestion0, which is a
trigger of vulnerability_heart0.
Note, however, that if an aggreg-part is triggered, this does not imply anything for
the triggering of the aggreg-complex. For example, in (Tablet), if solubility1 is triggered
by half-tablet1_in_solvent, this does not imply the triggering of solubility0 – as the
solubility2 of half-tablet2 may not be triggered (in case half-tablet2 is not put into a
solvent). Similarly, in (Poison), Jones might undergo some cardiac arrest which is not
due to the ingestion of poison, in which case heart_need0 is triggered without
vulnerability_heart_&_life0 being triggered.
4. Composition of various disposition-parthood relations
We will now show how we can use disposition-parthood relations to combine basic
dispositions into mereological complexes, by developing case studies involving dominos.
4.1. Domino arrangement
Let’s consider five dominos dominoi (for any integer iÎ[0,4]) vertically placed on their
short edge, such that they will fall if pushed. Each dominoi is thus the bearer of a
disposition unstability¬i that is realized by dominoi falling to the left (a process that is
an instance of the defined class Fall¬i) and triggered when dominoi is pushed to the left
(Push¬i); and the disposition unstability®i realized by dominoi falling to the right
(Fall®i) when dominoi is pushed to the right (Push®i). It also has a disposition
unstability®i /¬i to fall to either side (Falli equivalentTo (Fall¬i or Fall®i)) when pushed
(Pushi equivalentTo (Push¬i or Push®i)). We can characterize this by stating:
• unstability®i /¬i realized_in only Falli
• unstability®i /¬i has_trigger only Pushi
However, those two relations do not express the information that a Push¬i always leads
to a Fall¬i, and that a Push®i always leads to a Fall®i. Therefore, it is more informative
to say that unstability®i /¬i has the two mod-parts unstability®i and unstability¬i and
to ascribe the respective realizations and triggers to the mod-parts:
• unstability®i mod-part_of unstability®i /¬i
• unstability¬i mod-part_of unstability®i /¬i
The five dominos 0 to 4 are arranged as illustrated on figure 1a below (dominos 5 to 8
from figure 1b will be considered later):
Figure 1a Figure 1b
domino2 is placed to the right (when seen from the domino’s side) of domino1, such that
when domino1 falls to the right, it pushes domino2 to the right; therefore, in this
configuration, the endphase of an instance of Fall®1 is also an instance of Push®2.
Let’s define unstability®1,®2 as the disposition of domino1 and domino2 to fall to
the right (a process named Fall®1Ù®2 = Fall®1 + Fall®2) when domino1 is pushed to the
right (Push®1). We have:
• unstability®1 ,®2 realized_in only Fall®1Ù®2
• unstability®1 ,®2 has_trigger only Push®1
However, those two relations do not express the information that there is a causal chain.
Therefore, it is more informative to write that unstability®1,®2 is a chain-complex
composed by two chain-parts unstability®1 and unstability®2:
• unstability®1 chain-part_of unstability®1,®2
• unstability®2 chain-part_of unstability®1,®2
Suppose that domino3 is placed next to domino1, such that when one of these falls, it
does not push the other. Then, the system domino1+3 = domino1 + domino3 has a
disposition unstability®1:®3 of both dominos falling to the right (Fall®1Ù®3 = Fall®1 +
Fall®3) when both dominos are pushed to the right (Push®1Ù®3 = Push®1 + Push®3):
• unstability®1:®3 realized_in only Fall®1Ù®3
• unstability®1:®3 has_trigger only Push®1Ù®3
However, those two relations do not express the information that when an instance
push®1 + push®3 causes an instance of fall®1 + fall®3, it is push®1 that causes fall®1,
and push®3 that causes fall®3. Therefore, it is more informative to write that
unstability®1:®3 is an add-complex with two proper add-parts unstability®1 and
unstability®3:
• unstability®1 add-part_of unstability®1:®3
• unstability®3 add-part_of unstability®1:®3
domino4 is placed to the right of domino3 (like domino2 was placed to the right of
domino1), such that when domino3 falls to the right, it pushes domino4 to the right. The
disposition to Fall®3Ù®4 when Push®3 is noted unstability®3,®4.
Finally, domino0 is placed to the left of domino1, such that when domino1 falls to
the left, it pushes domino0 to the left. The chain-complex disposition to Fall¬1Ù¬0 when
Push¬1 is noted unstability¬1,¬0.
4.2. Composition of mod-part_of and chain-part_of
We can now combine these dispositions into more complex dispositions. domino1,2 =
domino1 + domino2 falls to the right (Fall®1Ù®2) when domino1 is pushed to the right
(Push®1), and domino1,0 falls to the left (Fall¬1Ù¬0) when domino1 is pushed to the left
(Push¬1). We can introduce the corresponding disposition unstability(®1,®2) / (¬1,¬0),
which is the disposition of [Fall®1Ù®2 when Push®1] and of [Fall¬1Ù¬0 when Push¬1]
(see figure 2). That is, unstability(®1,®2) / (¬1,¬0) is a mod-complex composed by the
mod-parts unstability®1,®2 and unstability¬1,¬0:
• unstability®1,®2 mod-part_of unstability(®1,®2) / (¬1,¬0)
• unstability¬1,¬0 mod-part_of unstability(®1,®2) / (¬1,¬0)
Moreover, by transitivity of the relation disp-part_of (of which mod-part_of and chain-
part_of are subrelations), we can state that unstability(®1,®2) / (¬1,¬0) is a disp-complex
composed by the disp-parts unstability®1, unstability®2, unstability¬1 and
unstability¬0.
Figure 2. Conjoint use of mod-part_of and chain-part_of
We have pointed out earlier that the bearer of a mod-part (resp. chain-part) is a part
of the bearer of a mod-complex (resp. chain-complex), but not necessarily the same
bearer; as a matter of fact:
• The bearer of the chain-complex unstability¬1,¬0 is domino1,0; whereas the
bearer of its chain-parts unstability¬1 and unstability¬0 are domino1 and
domino0, respectively.
• The bearer of the mod-complex unstability(¬1,¬0) / (®1,®2) is domino0,1,2;
whereas the bearers of its mod-parts unstability(¬1,¬0) and unstability(®1,®2)
are domino1,0 and domino1,2, respectively.
4.3. Further compositions
We could also express a large variety of dispositions thanks to the various parthood
relations introduced here. For example, domino1,3 has a disposition to [Fall®1Ù®3 when
Push®1Ù®3] and to [Fall¬1Ù¬3 when Push¬1Ù¬3], which is the mod-complex
unstability(®1:®3) / (¬1:¬3), composed by the add-complexes unstability®1:®3 and
unstability¬1:¬3.
To illustrate other configurations, consider the domino arrangement on Figure 1b.
domino5 is placed on the left of domino6 and domino7, in-between, such that if domino5
falls to the right, then both domino6 and domino7 also fall to the right. There is an
underlying disposition to Fall®5Ù®6Ù®7 when Push®5, which is the add-complex
unstability(®5,®6):(®5,®7) composed by the chain-complexes unstability®5,®6 and
unstability®5,®7. Now, domino8 is placed on the right of domino6 and domino7, such
that if either domino6 or domino7 falls to the right, then domino8 also falls to the right.
The underlying disposition to [Fall®6Ù®8 when Push®6] and to [Fall®7Ù®8 when Push®7]
is the mod-complex unstability(®6,®8) / (®7,®8) composed by the chain-complexes
unstability®6,®8 and unstability®7 ,®8.
Suppose now that domino8 is more massive, such that it needs both domino6 and
domino7 to fall to the right for domino8 to also fall to the right. The underlying
disposition to Fall®6Ù®7Ù®8 when Push®6Ù®7 is the chain-complex unstability(®6:®7) , ®8
composed by the add-complex unstability®6:®7 as well as by unstability®8.
Finally, we could compose dispositions in more intricate ways, mixing mod-part_of,
add-part_of and chain-part_of – consider for example the disposition
unstability[(®6:®7) , ®8] / [(¬6:¬7) , ¬5] to [Fall®6Ù®7Ù®8 when Push®6Ù®7] and to
[Fall¬6Ù¬7Ù¬5 when Push¬6Ù¬7].
5. Discussion and conclusion
This paper has presented different ways to compose dispositions together: mod-parthood
and aggreg-parthood, and the subrelations of the latter add-parthood and chain-parthood.
All of them are subsumed by disp-parthood, which satisfy some axioms (DISP-
BEARER), (DISP-TRIGGER) and (DISP-REALIZATION); and each of those
subrelations also satisfy more specific axioms.
All these relations of disposition-parthood are partial orders: they are reflexive,
transitive and anti-symmetric. To be authentic mereological relations, however, they also
need to satisfy axioms of composition and decomposition (see [4] for a few preliminary
remarks concerning mod-part_of). It can easily be seen that composition axioms can be
introduced at least for some disposition-parthood relations. For any two dispositions d1
and d2 (with bearers b1 and b2) there exists a mod-complex noted (d1/d2) and an add-
complex noted (d1:d2), which inheres in b1+b2. On the other hand, there exist a chain
complex (d1,d2) (also inhering in b1+b2) only if the maximally specified realization class
of d1 has as part the class of triggers of d2. By introducing such axioms of composition,
we commit ourselves to a lot of strange disposition complexes, such as complexes of
dispositions of different bearers, that might even exist at different times. This, however,
is no special feature of disp-parthood: the same phenomenon occurs in standard
mereology. Moreover, the formal commitment to the existence of these mereological
sums does not imply any commitment that all of them have causal or explanatory
relevance.
Consider now axioms of decomposition. Although this would require further
investigations, the following axiom of complementation [6] seems to be satisfied for P
being any of the five relation of disposition-parthood mentioned above, and O the
associated relation of overlapping:
¬Pyx → ∃z ∀w (Pwz ↔ (Pwy Ù ¬Owx))
Note that our taxonomy of relations of disposition-parthood is not meant to be
exhaustive. For example, one could consider the disposition realized by (only) domino2
falling to the right when domino1 is pushed to the right – not to be confused with the
above disposition unstability®1,®2 realized by both domino1 and domino2 falling to the
right when domino1 is pushed to the right.
By way of conclusion we point out that we expect disposition-parthood to be a
powerful tool to explore relations between medical entities that have been formalized as
dispositions, such as diseases [7, 8] or medical risks [9].
Acknowledgements
AB acknowledges financial support by the “Bourse de fellowship du département de
médecine de l’université de Sherbrooke” and the CIHR-funded Quebec SPOR Support
Unit.
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