Biology Reference
In-Depth Information
debated in the nineteenth century. The opponents to explaining biological phe-
nomena in terms of mechanisms were often labeled
vitalists
. Although there
was no official vitalist doctrine (just as there was no official doctrine of those
advancing mechanism), vitalists tended to insist that ordinary physical objects
could not generate the phenomena associated with living organisms and to main-
tain that explaining such phenomena required appeal to additional factors such
as vital forces or vital powers. Some vitalists proposed that there was a nonphys-
ical component of living organisms that gave them their distinctive properties.
Others downplayed the radical nature of such appeals, arguing that vital forces
were not substantially different from the sorts of forces Newton had invoked to
explain the behavior of physical objects. The behavior of living organisms could
be described in distinctive laws of biology that invoked vital forces, and biolo-
gists were no more obliged than Newton to explain them in more fundamental
terms.
11
The historical importance of vitalists lies not in their positive doctrine of vital
forces or vital powers, but in their critique of mechanism. They drew attention to
phenomena exhibited by living organisms that mechanists seemed incapable of
explaining. The natural tendency of mechanists was to focus on the phenomena
they could explain, and to divert their attention from the phenomena that proved
more difficult. Vitalists thus provided an honesty check on mechanists, keeping
in focus the phenomena of life that were recalcitrant to existing mechanist
explanatory strategies.
An exemplar of the vitalist challenge to mechanism is offered by the French
anatomist Xavier Bichat. His project began in the fashion of a mechanist as he
proposed a decomposition of living systems into 21 different types of tissues
distinguishable in terms of their sensibility and contractility. He then appealed
to these properties to explain the phenomena associated with organs built from
these tissues. But with the catalogue of tissues, Bichat contended, this explana-
tory project reached a limit. He highlighted two reasons for resisting any attempt
to explain the phenomena associated with tissues in terms of their material
composition. The behavior of living organisms was simply not sufficiently deter-
ministic to be explained mechanistically: 'The instability of vital forces marks
all vital phenomena with an irregularity which distinguishes them from physical
phenomena [which are] remarkable for their uniformity' (Bichat, 1805, p. 81).
Moreover, he contended that living organisms operate to resist external fac-
tors that threaten their existence, construing life as 'the sum of all those forces
which resist death'. This last characterization is particularly potent. The notion
of resistance points to self-initiated action, where that action is directed at main-
taining the living organism as a distinct system. As we will see, the construal
11
For an account of the positions of various vitalists and mechanists in the history of physiology, see
Hall (1969).
