THE FACTORY MODEL OF DISEASE * * * * * *

Neil E. Williams (University at Buffalo) Philosophy of Biology Symposium September 29 th 2007

1

Three Aims of this Presentation:

Primary Aim:

Suggest a new metaphor for thinking about disease 2

Germ Theory of Disease Attack by Foreigners

3

Germ Theory of Disease

Useful in 19 th Century; now antiquated Misses out on a great number of diseases: genetic diseases, immune system diseases, nutritional deficiencies, mental illnesses 4

Three Aims of this Presentation:

Primary Aim:

Suggest a new metaphor for thinking about disease

Secondary Aims:

Reconsider the place of causation in disease Offer a refurbished analysis of ‘disease’ 5

Plan of Attack

1 - Distinguish diseases from disorders 2 - Standards for structure 3 - Causes and Cellular Processes 4 - The Factory Model 5 - Disease Re-Defined 6

1: Disease vs. Disorder

7

• Part of establishing a clear understanding of disease requires distinguishing cases of disease from non-disease • This helps restrict the class of diseases, but will also provide a parallel framework against which disease can be understood 8

Because ‘disease’ has long been treated as the ‘absence of health’, there has been a tendency to lump in all sorts of medical conditions under a the general name ‘disease’ Broken Arms Hernias Ingrown Toenails Gall Stones Color-blindness 9

Disorders

• • • By ‘disorder’ I will understand a purely

structural deviation

from the norm ‘Structure’ is an anatomical catch-all including: topography, shape, proportion and number Determination of disorder is independent of cause and of need for medical attention 10

2: Standards for Structure

11

• Disorders are bodily states of anatomical abnormality • They are deviations—as such they arise against a backdrop of structural normality • But what is normal?

12

• Within comparison classes we find a high degree of structural similarity • This allows us to determine statistical averages that determine a standard (Foundational Model of Anatomy – Rosse and Mejino 2003) • Comparison is made against that standard 13

The Canonical Skeleton

• An excellent case concerns the human skeleton • The

canonical skeleton

is part statistical average, part prototype, so is insensitive to minor contingent peculiarities • Canonical is not ideal (ideal for what?) • Consider the IRS’s concept of average tax payer: it is not merely a numerical average 14

• Other disorders are modeled on the skeletal case: musculature, cells, organs, vascular system • We have excellent information about human biological architecture • Borderline cases come out in the wash (medical practitioners are highly successful at recognizing and naming what I have called ‘disorders’) 15

• The general model of deviation as it pertains to disorder will be used in the consideration of disease • Disorder concerns bodily structure; disease concerns cells and cellular processes • Disease will be defined against a backdrop of standard processes of cellular interation 16

3: Causes and Cellular Processes

17

Cells as ‘Power-Centres’

• Every cell has, as part of its biological programming, a vast range of capacities • The causal ‘preparedness’ of the cell includes instructions for what to do in the presence or absence of various molecules and other cells • Most responses are homeostatic and fall within a limited range 18

• Due to contingent features, only a small number of these capacities are ever exercised • Cells are not agents: responses are programmed • Typically stable environments makes for routine cellular responses 19

• Cellular environments include various chemicals, but also other cells • Cells operate

reciprocally

with other cells • Cells individually contribute to what are

mutual

effects • These co-operative interactions make for

cellular networks

20

4: The Factory Model

21

• We can think of the actions of the cell within a cellular network (or within the body as a whole) as analogous with the place of the assembly-line factory worker within the factory 22

23

Simple Tasks; Complex Results

• Humans owe their biological complexity and adaptive success to the same features that make assembly-lines so good for output: Division of labour Specialized tasks Bringing work to the worker 24

• But just like the factory worker, that a cell performs a specific role does not mean it is not capable of far more • Cells can be re-assigned within the body to perform different tasks, just like a factory worker who labels bottles can be asked to cap them instead 25

• Reflecting on the cell/factory worker analogy, we can get a rudimentary sense of the account of disease on offer when we imagine some ways how things might go wrong at the factory • the method of breakdown or cessation of factory production is akin to distortions of typical cellular processes, and those distorted processes will constitute diseases 26

Trouble at Mill?

1 – Problems internal to the worker Shirley is sick, hungry, confused 2 – Problems within/across Co-workers Laverne is angry, jealous, confused 3 – Lack of Resources 4 – Lack of Power 5 – Assembly line blockages 27

Trouble at Cell?

1 – Problems internal to the cell Cell cannot operate; instructions 2 – Problems within/across cells Miscoding; chemical issues 3 – Lack of Resources 4 – Lack of Energy 5 – Physical Occlusions 28

• • •

Disease or Disorder?

You may have noted that some of the problems are themselves disorders The disorder is not the disease, but could be a

cause

As might be expected, disorders can give rise to distorted cellular processes, thereby resulting in diseases (and diseases might give rise to disorders) 29

• • •

Disease or Symptom?

Mistaking disorders for disease is akin to mistaking symptoms for diseases A symptom is something that arises because of a disease, but is not the disease itself It can serve as an indicator of a disease 30

5: Disease Re-Defined

31

x is a disease = df x is a prolonged distortion of cellular network processes, wherein the activities of the network: (i) fall outside an acceptable normal range for the organism’s comparison class, 32

x is a disease = df x is a prolonged distortion of cellular network processes, wherein the activities of the network: (ii) are not capable of remedy by the system itself without thereby distorting the activities of some other network, and 33

x is a disease = df x is a prolonged distortion of cellular network processes, wherein the activities of the network: (iii) tend to reduce the organism’s ability to cope with environmental pressures 34