Mayr E. What Makes Biology Unique? : Considerations on the Autonomy of a Scientific Discipline

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what makes biology unique?

A proliferation of sciences

Beginning with the sixteenth century, the scientiﬁc revolution was ac-

companied by the origin of several other sciences, which included his-

torical sciences such as cosmology and geology and various ﬁelds tradi-

tionally considered parts of the humanities, such as psychology, anthro-

pology, linguistics, philology, and history. They all became increasingly

scientiﬁc in the ensuing centuries. This was particularly true for research

eventually combined under the name biology.

Aristotle in the fourth century b.c. had produced a remarkable contri-

bution to biology, particularly to its methodology and principles. Even

though a few additional interesting discoveries were later made in the

Hellenic period and by Galen and his school, biology remained more

or less dormant until the sixteenth century. Some contributions, how-

ever, were made in two widely distant areas. The medical schools from

the sixteenth century on were beginning to make advances in anatomy,

embryology, and physiology; at the same time, natural history, in the

broadest sense of the word, was equally furthered by natural theologians

like Ray, Derham, and Paley; by naturalists like Buffon and Linnaeus;

and by numerous lay naturalists.

As we shall see, in the seventeenth and eighteenth centuries students

of the living world, both at the medical schools and among the natural

historians (natural theology), actively laid a foundation for a science of

biology. Yet, that such a ﬁeld as biology existed was almost universally ig-

nored by historians and philosophers. When Kant (1790), in his Critique

of Judgment, was quite unsuccessful in explaining the phenomena of the

living world with the help of Newtonian laws and principles, he solved

his dilemma by ascribing biological processes to teleology. Most other

philosophers simply ignored the existence of biology. Science is physics,

they said simply. More recently, the writings of philosophers of science

from the Vienna School to Hempel and Nagel and to Popper and Kuhn

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science and sciences

were strictly based on and applicable to the physical sciences. When C. P.

Snow decried the gap between science and the humanities, he actually

described the gap between the physical sciences and the humanities.

Biology was nowhere referred to in his discussions. As late as the 1970s

and 1980s various philosophers (e.g., Hull 1974, Ruse 1973, Sober

1993) wrote philosophies of biology essentially based on the conceptual

framework of the physical sciences. Of course, their education usually

had been in logic or mathematics, rather than in biology.

Some authors broke away from this monopoly of the physical sciences

(often referred to as Cartesianism) because they realized that these strictly

physicalist endeavors were not an adequate foundation for a philosophy

of biology. But their proposal was not the sought-for solution either,

because they invoked occult forces (vitalism and teleology). The last well-

known representatives of this vitalistic approach were Bergson (1911)

and Driesch (1899) (see chapter 2). Even though these authors sensed

that vitalism was an invalid approach, they were unable to ﬁnd a better

solution. For me it became clear in the 1950s that any approach to

a philosophy of biology, essentially based on logic and mathematics

rather than on the speciﬁcally unique concepts of biology, would be

unsatisfactory. The solution had to come from biology, but what would

biology have to do to ﬁnd it?

Why is biology different?

In spite of spectacular developments such as genetics, Darwinism, and

molecular biology, biology continued to be treated as a branch of phys-

icalist science. Only a few philosophers realized that mechanics as well

as all post-Galileian sciences, consisted of two types of attributes. These

are, ﬁrst, the characteristics all genuine sciences share, including the or-

ganization and classiﬁcation of knowledge on the basis of explanatory

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what makes biology unique?

principles (Mayr 1997). The other attributes consist of characteristics

that are speciﬁc for a particular branch of science or group of sciences. In

the case of mechanics, this would include the special role of mathematics,

the foundation of its theories on natural laws, and a much greater ten-

dency toward determinism, to typological thinking, and to reductionism

than found in biology. None of these mechanics-speciﬁc characteristics

plays a major role in theory formation in biology.

When the philosophy of science began to originate, the philosophers

apparently took it for granted that all kinds of science were equivalent

as far as philosophy is concerned. This is why Galileo, Kant, and indeed

most philosophers of science applied to biology, without change, a phi-

losophy that had been developed on the basis of mechanics. And the same

guideline was used for all sciences: anthropology, psychology, sociology,

and others. What is needed instead is a careful analysis of each science to

determine whether its basic principles and components are adequately

covered by the explanations of mechanics and more broadly by those of

physics. As a ﬁrst contribution to this project, I have undertaken this

task for biology. My ﬁndings are presented in chapter 2, “The Autonomy

of Biology.”

literature cited

Bergson, H. 1911. L’Evolution Cr´eatrice. Paris: Alcan.

Darwin, C. 1859. On the Origin of Species by Means of Natural Selection or the

Preservation of Favored Races in the Struggle for Life. London: John Murray

[1964, Facsimile of the First Edition; Cambridge, MA: Harvard University

Press].

Driesch, H. 1899. Philosophie des Organischen. Leipzig: Quelle und Meyer.

Galileo, G. 1632 (2001). Dialogue Concerning the Two Chief World Systems. Ptole-

maic and Copernican. Translated by S. Drake. New York: Modern Library.

Garber, D., and A. Ariew. 1998. Introduction: Leibniz and the sciences. Per-

spectives on Science, 6:1–5.

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science and sciences

Hull, D. L. 1974. Philosophy of Biological Science. Englewood Cliffs, NJ: Prentice-

Hall.

Kant, I. 1790. Die Kritik der Urteilskraft. Berlin: Georg Reimer.

Kitcher, P. 1984. 1953 and all that. Philosophical Reviews, 93:335–373.

Mayr, E. 1997. This Is Biology. The Science of the Living World. Cambridge, MA:

Harvard University Press, chapt. 2, pp. 24–49.

Pais, A. 1982. Subtle is the Lord: The Science and the Life of Albert Einstein. Oxford:

Oxford University Press.

Roger, J. 1997. Buffon: A Life in Natural History. Translated by S. L. Bonnefoi.

Ithaca: Cornell University Press.

Rosenberg, A. 1985. The Structure of Biological Science. Cambridge, NY: Cam-

bridge University Press.

Ruse, M. 1973. The Philosophy of Biology. London: Hutchinson.

Ruse, M. 1979. Darwinian Revolution: Science Red in Tooth and Claw. Chicago:

University of Chicago Press.

Sober, E. 1993. Philosophy of Biology. Boulder: West View Press.

Woese, C. R. 2002. On the evolution of cells. Proceedings of the National Academy

of Sciences, 99:8742–8747.

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The Autonomy of Biology

It took more than two hundred years and the occurrence of three

sets of events before a separate science of the living world – biology –

was recognized. As I will show, one can assign these events to three

different sets: (A) the refutation of certain erroneous principles, (B) the

demonstration that certain basic principles of physics cannot be applied

to biology, and (C) the realization of the uniqueness of certain basic

principles of biology that are not applicable to the inanimate world.

This chapter is devoted to an analysis of these three sets of developments.

This has to be done before one can accept the view of an autonomy of

biology. For an earlier support of the autonomy of biology see Ayala

(1968).

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what makes biology unique?

The refutation of certain erroneous basic assumptions

Under this heading, I deal with the support for certain basic ontological

principles that later were shown to be erroneous. Biology could not

be recognized as a science of the same rank as physics as long as most

biologists accepted certain basic explanatory principles not supported by

the laws of the physical sciences and eventually found to be invalid. The

two major principles here involved are vitalism and a belief in cosmic

teleology.Assoon as it had been demonstrated that these two principles

are invalid and, more broadly, that none of the phenomena of the living

world is in conﬂict with the natural laws of the physicalists, there was no

longer any reason for not recognizing biology as a legitimate autonomous

science equivalent to physics.

Vitalism

The nature of life, the property of being living, has always been a puzzle

for philosophers. Descartes tried to solve it by simply ignoring it. An or-

ganism is really nothing but a machine, he said. And other philosophers,

particularly those with a background in mathematics, logic, physics, and

chemistry, tended to follow him and operated as if there were no differ-

ence between living and inanimate matter. But this did not satisfy most

naturalists. They were convinced that in a living organism certain forces

are active that do not exist in inanimate nature. They concluded that,

just as the motion of planets and stars is controlled by an occult, invisible

force called gravitation by Newton, the movements and other manifesta-

tions of life in organisms are controlled by an invisible force, Lebenskraft

or vis vitalis. Those who believed in such a force were called vitalists.

Vitalism was popular from the early seventeenth century to the early

twentieth century. It was a natural reaction to the crass mechanism of

Descartes. Henri Bergson (1859–1941) and Hans Driesch (1867–1941)

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the autonomy of biology

were prominent vitalists in the early twentieth century. The end of vi-

talism came when it no longer could ﬁnd any supporters. Two causes

were largely responsible for this: ﬁrst, the failure of literally thousands

of unsuccessful experiments conducted to demonstrate the existence of a

Lebenskraft; second, the realization that the new biology, with the meth-

ods of genetics and molecular biology, was able to solve all the problems

for which scientists traditionally had invoked the Lebenskraft. In other

words, the proposal of a Lebenskraft had simply become unnecessary.

It would be ahistorical to ridicule vitalism. When one reads the writ-

ings of some of the leading vitalists like Driesch, one is forced to agree

with him that many of the basic problems of biology simply cannot

be solved by Cartesian philosophy, in which the organism is considered

nothing but a machine. The developmental biologists, in particular,

asked some very challenging questions. For example, how can a machine

regenerate lost parts, as many kinds of organisms are able to do? How

can a machine replicate itself? How can two machines fuse into a single

one like the fusion of two gametes to produce a zygote?

The critical logic of the vitalists was impeccable. But all their efforts to

ﬁnd a scientiﬁc answer to the so-called vitalistic phenomena were failures.

Generations of vitalists labored in vain to ﬁnd a scientiﬁc explanation

for the Lebenskraft until it ﬁnally became quite clear that such a force

simply does not exist. That was the end of vitalism.

Teleology

Teleology is the second invalid principle that had to be eliminated from

biology before it qualiﬁed as a science equivalent to physics. Teleol-

ogy deals with the explanation of natural processes that seem to lead

automatically to a deﬁnite end or goal. To explain the development of

the fertilized egg to the adult of a given species, Aristotle invoked a

fourth cause, the causa ﬁnalis. Eventually, one invoked this cause for all

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what makes biology unique?

phenomena in the cosmos that led to an end or goal. Kant in his Cri-

tique of Judgment at ﬁrst tried to explain the biological world in terms of

Newtonian natural laws but was completely unsuccessful in this en-

deavor. Frustrated, he ascribed all Zweckm¨assigkeit (adaptedness) to tele-

ology. This was, of course, no solution. A widely supported school of evo-

lutionists, for instance, the so-called orthogenesists, invoked teleology

to explain all progressive evolutionary phenomena. They believed that in

living nature there is an intrinsic striving (“orthogenesis”) toward perfec-

tion. Here belongs also Lamarck’s theory of evolution, and orthogenesis

had many followers before the evolutionary synthesis. Alas, no evidence

for the existence of such a teleological principle could ever be found,

and the discoveries of genetics and paleontology eventually totally dis-

credited cosmic teleology. For a more detailed discussion of teleology see

chapter 3.

What is biology?

When we try to answer this question, we ﬁnd that biology actually

consists of two rather different ﬁelds, mechanistic (functional) biology

and historical biology. Functional biology deals with the physiology of

all activities of living organisms, particularly with all cellular processes,

including those of the genome. These functional processes ultimately

can be explained purely mechanistically by chemistry and physics.

The other branch of biology is historical biology.Aknowledge of history

is not needed for the explanation of a purely functional process. However,

it is indispensable for the explanation of all aspects of the living world

that involve the dimension of historical time – in other words, as we

now know, all aspects dealing with evolution. This ﬁeld is evolutionary

biology.

The two ﬁelds of biology also differ in the nature of the most frequently

asked questions. To be sure, in both ﬁelds one asks “what?” questions to

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the autonomy of biology

get the facts needed for further analysis. The most frequently asked ques-

tion in functional biology, however, is “how?”; in evolutionary biology

“why?” is the most frequently asked question. This difference is not com-

plete because in evolutionary biology one also occasionally asks “how”

questions – for instance, how do species multiply? However, as we will

see, to obtain its answers, particularly in cases in which experiments are

inappropriate, evolutionary biology has developed its own methodology,

that of historical narratives (tentative scenarios).

To truly appreciate the nature of biology one must know the remark-

able difference between these two branches of biology. Indeed, some of

the most decisive differences between the physical sciences and biology

are true for only one of these branches, for evolutionary biology.

The emergence of modern biology

The two-hundred-year period from about 1730 to 1930 witnessed a rad-

ical change in the conceptual framework of biology. The period from

1828 to 1866 was particularly innovative. Within these thirty-eight

years, both branches of modern biology – functional and evolutionary

biology – were established. Yet biology was still largely ignored by the

philosophers of science from Carnap, Hempel, Nagel, and Popper to

Kuhn. Biologists, even though they now rejected vitalism and cosmic

teleology, were unhappy with a purely mechanistic (Cartesian) philoso-

phy of biology. But all endeavors to escape from this dilemma – such as,

for example, the writings of Jonas, Portmann, von Uexk

ull, and several

others – invariably invoked some nonmechanical forces that were not ac-

ceptable to most biologists. The solution had to satisfy two demands: it

had to be completely compatible with the natural laws of the physicists,

and no solution was acceptable that would invoke any occult forces. It

was not until almost the middle of the twentieth century that it became

evident that a solution could not be found by a philosopher who did not

have a background in biology. But no such philosopher made the attempt.