sheet provided before giving or refusing consent. That person is vulnerable. A poten-
tial research participant who is severely intellectually disabled might face the same
problem; he might not be able to understand the information provided for consent and
is therefore vulnerable as well. There is an important difference between the abilities
of these two potential research participants, though. The illiterate research participant
might be able to learn to read and would then no longer be vulnerable, or at least not
in that respect. That person is contingently vulnerable: she lacks the means rather than
the physical or mental abilities to protect herself. 4 The intellectually disabled research
participant, on the other hand, is intrinsically vulnerable. 5 He truly lacks the (mental)
ability to protect himself whatever alternative consent procedures are considered. We
will reserve the word 'ability' for intrinsic abilities, and use the word 'means' for
what determines contingent abilities, such as literacy, education, resources, and social
and economic status. We will therefore rephrase the internal element of our definition
to refer to the 'ability or means to protect oneself'. And now we can present our final
definition of vulnerability.
To be vulnerable means to face a significant probability of incurring an identi-
fiable harm, while substantially lacking the ability or means to protect oneself.
Now that we have provided a definition of 'vulnerability', we turn to the possi-
ble over-extension of vulnerability. The World Medical Association's Declaration of
Helsinki on Ethical Principles for Medical Research Involving Human Subjects, the
Declaration of Helsinki for short, is the most important international guideline for the
governance of ethical medical research. Following a revision of the Declaration of
Helsinki in the year 2000 (the version prior to the current one), article 8 stated:
Some research populations are vulnerable and need special protection. The particular needs
of the economically and medically disadvantaged must be recognized. Special attention is
also required for those who cannot give or refuse consent for themselves, for those who
may be subject to giving consent under duress, for those who will not benefit personally
from the research and for those for whom the research is combined with care (WMA 2004 ).
This article was heavily criticized for making everyone, and thereby no one,
vulnerable. Forster et al. ( 2001 ) made this point very succinctly:
The new declaration goes further [than the old one], making every conceivable person vul-
nerable, from patients with an illness, to those who cannot give consent, to healthy vol-
unteers … The new declaration expands the category of vulnerability so broadly that it
eliminates this category …; if everyone is vulnerable, no one is entitled to special protection.
Paragraph 8 was revised in 2008 to read (now as paragraph 9):
4 In this case, researchers are also in a position to empower her by, for instance, facilitating ver-
bal, recorded consent, if this is acceptable to her.
5 For a further discussion of this distinction see Silvers ( 2004 , p. 56).