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the systemic model allows a knowledge model to be elaborated which takes into
consideration different ideas, including:
•
Disease and health affect an organism, not isolated organs.
•
What is normal and pathological cannot be defined by universal parameters that
are external to the social and environmental conditions in which they act. The
organisms of patients interact with their physical and social environment and oc-
casionally a disease cannot be separated from the physical environment in which
it appears. At the same time, the perception of when an individual is considered
to be sick (and therefore consults an expert on the state of their health) depends
on the social context of their daily life.
From the point of view of constructing the discipline, the systemic model allows
the incorporation of different areas of knowledge (identified throughout this work,
regarding the different disciplines used in Medicine, as well as the objective and
subjective knowledge used in medical practice) to be understood, as well as their
relevance in the development of Medicine. From the point of view of working in the
profession, the systemic model allows the abilities of experts in the process of con-
structing their field to be represented. Finally, it allows the criteria of validity linked
to the resolution of problems to be incorporated, as well as uncertainty, not as a lim-
itation of the available knowledge, but rather as an epistemological characteristic of
the problems studied in the field of Medicine.
8.7
The Representation of Expert Knowledge in Medicine
There are no universal rules in the expert knowledge of Medicine, there are per-
spectives on how to analyse and resolve problems. From this it can be deduced
that medical knowledge cannot be represented using unequivocal rules that con-
nect evidence and standardised protocols. Until relatively recently, few defended
the idea that medical knowledge could be modelled in 'expert programmes' that al-
lowed rules to be defined with associated degrees of uncertainty[11]; however our
analysis creates a new situation that is represented in the following concept map
(see figure 8.1).
This representation highlights how the information that medical experts work
with have different typologies. Some information is precise (laboratory tests) oth-
ers are fuzzy (symptomology, subjective information provided by the patient, the
subjective perception of the doctor, placement of the information provided by the
patient in categories of contemporary medical knowledge, the subjective interpreta-
tion of the existence of disorders). In addition, the heuristic reasoning of the expert
incorporates probability and possibility. In the case of making a diagnosis based on
probability, the expert uses statistical estimation when studying cases. In the case
of making a diagnosis using the criteria of possibility, the intuition of the expert
intervenes. Thus, contemplating what is possible appears as a consequence of hav-
ing evaluated and discarded what is probable. A possibilistic diagnosis is based on
knowledge of studies and research that has been carried out on exceptional cases,
