1. 1 THE FACTORY MODEL OF DISEASE * * * * * * Neil E. Williams (University at Buffalo) Philosophy of Biology Symposium September 29 th 2007

2. 2 Three Aims of this Presentation: Primary Aim: Suggest a new metaphor for thinking about disease

3. 3 Germ Theory of Disease Attack by Foreigners

4. 4 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

5. 5 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’

6. 6 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

7. 7 1: Disease vs. Disorder

8. 8 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

9. 9 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

10. 10 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

11. 11 2: Standards for Structure

12. 12 Disorders are bodily states of anatomical abnormality They are deviations—as such they arise against a backdrop of structural normality But what is normal?

13. 13 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

14. 14 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

15. 15 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’)

16. 16 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

17. 17 3: Causes and Cellular Processes

18. 18 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

19. 19 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

20. 20 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

21. 21 4: The Factory Model

22. 22 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

23. 23

24. 24 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

25. 25 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

26. 26 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

27. 27 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

28. 28 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

29. 29 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)

30. 30 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

31. 31 5: Disease Re-Defined

32. 32 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,

33. 33 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

34. 34 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