Intended for healthcare professionals


Evidence based medicine: what it is and what it isn't

BMJ 1996; 312 doi: (Published 13 January 1996) Cite this as: BMJ 1996;312:71

Re: Is EBM a Belief?


In a previous email [1] I am rightly accused by Joseph Watine of
calling EBM little more than a religious belief. This viewpoint can be
approached from two directions in order to show that it might be valid. As
everybody knows, anything that cannot be seen, felt, touched or detected
in some way can only be assumed to exist. Science quite strictly demands
that only those things that can be proven or demonstrated, are permitted
to enjoy the status of being real. Those conceptual or abstract things we
regularly assume to exist fall subject to similar requirements, and if
they fail this test then they are not considered to be real, but merely
convenient assumptions or beliefs.

In religion, such things as God and soul are certainly beliefs of
this type, because they cannot be unequivocally demonstrated. Religions,
therefore, might be distinguished from science in not enforcing this
requirement that the claims of beliefs must be demonstrable. The ‘truths’
of religions, like the arts and humanities, tend to be evaluated in our
life experience rather than through the material proof of hard science.
Such beliefs tend to be measured according to how happy they make you feel
rather than whether they can be proved.

In certain forms of medicine, we find conceptual entities that are
believed to exist. Thus, the vital force and potency energy in homeopathy,
the Qi and meridians in acupuncture, the toxins in nature cure and the
subluxations or joint misalignments in osteopathy - these are all
conventionally thought to fall into the same category of pure beliefs.
However, in every case there exists a body of evidence, within each
specialty, that confirms the conceptual entity, underpins it and validates
a continued belief in it. Otherwise, clearly, such beliefs would have died
out long ago. While this does not actually conclusively prove the
existence of such entities, as science demands, it is sufficient to
maintain an ongoing practical acceptance that such entities are there -
they can be accepted as ‘working hypotheses’ and valid models.

Even in science itself similar concepts abound - things like light-
year, electron, force field, proton, quark, etc dwell in a similar
borderland of being assumed to exist but not being solidly proven. At the
practical level, they can be mathematically or inferentially demonstrated
but as no-one can see or touch them, they can never be completely proven
as real. Science is not composed solely of ‘facts’ but also contains a
surprising range of such unproven conceptual entities that add to the
smooth conceptual fabric of the discipline. Whether that fact in any way
influences the philosophical certainty of science is an open question. As
with vital force and toxins [etc], there is a mass of evidence within
science to sustain a continued belief in these concepts, but beliefs they
certainly are. Thus, when we come to look at EBM, we must demand of it
some definitions and observations that support the provisional conceptual
‘reality’ that people choose to invest in it. If such evidence cannot be
adduced, clearly and for all to see, then we are correct to conclude that
it is no more real than the fairies. I contend that there is no such
evidence and thus EBM is just a transient fashion in medicine, an
invention and a conception idly plucked from the air, which some people
have latched onto as a new saviour in medicine.

The second approach involves tracking those 'conceptual errors' that
collectively lead one to suppose that EBM is a real entity. These
'conceptual errors' are those through which modern medicine views the
organism: what we might call ‘conceptual spectacles’ through which it
habitually and unwittingly views the functioning of the organism, and with
which it explains life phenomena and how it arrives at 'medical truth'. If
it can be demonstrated that these ‘conceptual spectacles’ only lead to a
certain viewpoint, which, upon closer inspection, does not accord with the
actual functioning of the human organism, then clearly one is then
entitled to conclude that it is only a partial picture, rather than the
full truth. Scientific hypotheses cannot stand supreme over observations;
those that conflict with data must be amended or abandoned - in science,
the real world is king.

Having chosen to follow a certain track since the 1850s, the
conceptual fabric of modern medicine inevitably faces a future crisis. Any
sober analysis of its approach to the organism most certainly does reveal
that it possesses conceptual spectacles and only views organism
functioning through them. If it were willing to change those spectacles,
then of course it could obtain very different views of the organism and
hence very different ideas of what medicine is about. It is precisely in
an arena of mature well-reasoned debate, tolerant respect and
philosophical inquiry, that the various claims and evidences of the
different healing modalities, should be brought and evaluated patiently,
neutrally and without prejudice. If such a task is ever undertaken then it
will be possible to show that no single medical approach can claim
superiority over any other. All have some claims on 'medical truth' and
all can be shown to have some clinical validity and some understanding of
how the organism functions. However, seemingly such a time is not yet upon
us and we ‘see but through a glass darkly’.

In fact, the same 'conceptual errors' that lead one to a belief in
EBM, also lead to a belief in colo-rectal cancer as a real entity. I
therefore ask Joseph Watine to provide the evidence and the observations
for the existence of EBM and colo-rectal cancer. If he can provide this
evidence then we can accept that these things are real. If he cannot, then
it will be clear that they are merely beliefs or conceptual fabrications
visible only when viewed through certain conceptual spectacles.

Avoiding any rash, simplistic or literal interpretation, he should
carefully consider the fundamental conceptual error contained in the
following statement: “we need to find proper cross sectional studies of
patients clinically suspected of harbouring the relevant disorder.” [2].
This phrase reveals the source of 'conceptual errors'. Implicitly, I shall
be assuming that this article by Sackett et al is a genuine, lucid and
definitive attempt to summarise what EBM is.


[1] BMJ letter, Joseph Watine, 2 December 2000, Is EBM a belief?

[2] Sackett DL, Rosenberg WMC, Gray JAM, et al. Evidence based
medicine: what it is and what it isn't. BMJ 1996; 312: 71-72

Competing interests: No competing interests

05 December 2000
Peter Morrell
Hon Research Associate, History of Medicine
Staffordshire University