Philosophy of biology

The philosophy of biology (also Biophilosophie ) is a branch of the philosophy of science. Topics of philosophy of biology are the philosophical assumptions, conditions, and reviews of biological theories, experimental research and applications. In addition to the methods of analytic philosophy of science belong to the philosophy of biology and the history of science and the sociology of science theories.

In a broader sense is discussed in the philosophy of biology and how models and methods from biology affect broader issues of philosophy; For example, with the concept of evolutionary epistemology, in which the principle of biological evolution is applied to the structure and possibility of knowledge. The growing importance of biological subject areas such as genetic engineering or molecular biology and the increasing mechanization and commodification in recent decades led also to the countless and ongoing ethical issues and debates. The same applies to the ecology that has gained a broad social significance in the context of nature conservation. So the biology and, with its diverse subject areas and methods partly as the future pluralistic " model discipline " and " century science" and as such should replace the physics and physicalism. The transitions of the philosophy of biology to theoretical biology and neuroscience philosophy are fluid.

• 4.1 What is life?
• 4.2 Status and structure of the theory of evolution 4.2.1 Meaning of the Theory of Evolution
• 4.2.2 challenge evo-devo

• 4.7.1 Molecular genetics versus
• 4.7.2 Genetic information, genetic program

Importance

The philosophy of biology is involved in many cases, to resolve research questions in biology with practical significance and solve. It comes in addition to general problems of the theory of science often to clarify the positions, theories and concepts within biology, but also controversy about the social impact of biological knowledge and technologies.

In the second half of the 20th century, the philosophy of biology received a great importance thrust, which is justified by the scientific and technological development in biology, but also in the development of society. The conservation debate and the emergence of the debate about the proper relationship to the ecology drew attention to the issue of anthropogenic influences on natural events. The mechanization and commodification of biology in biotechnology and genetic engineering, however, calls for ethical, ontological and epistemological answers. And finally present the results of Neurobiology new questions of a technical applicability and after the image of man within biology.

Philosophers who deal with biological issues are often self -trained biologists. Likewise, several biologists like Ernst Mayr, Richard Dawkins and Michael Ghiselin have made ​​significant contributions to philosophy of biology. Since 1985, the journal "Biology and Philosophy " appears.

The philosophy of biology has long focused on evolutionary biology and status of the organisms and neglected rather the physico- chemically oriented branches of biology such as molecular biology. On the other hand, enriched the philosophy of biology so in many ways large areas of philosophy itself Against what the technically and physically - chemically embossed disciplines and their philosophical reflection are covered in most cases already by more general epistemological work. Concepts and terms in biology, which stand out from the general epistemological issues, the duality of phenotype and genotype, the historical element, the uniqueness and the variety of organization and complexity of many objects of investigation, but also the concept of life itself, teleology, for example, ( functional purpose ) and natural selection. After the physics and in particular the mechanics have for centuries dominated the models and methods of science theory, now the question arises, what is the status of biology in the philosophy of science. This question and answers cover all areas of dealing with the biology and, ultimately, questions of logic, methodology and concrete research practice.

The philosophy of biology mostly operates the reflection of biological concepts, theories and methods - that is the work of philosophers to dealing successfully with content of biological research. Conversely, many influences on general topics and areas of philosophy have become much more about this employment. The best known examples are the Evolutionary epistemology for epistemology, bioethics, but also an essential part of the current anthropological topics. Similarly, the Biophilosophie with their pluralistic, ecological and historical approaches to the challenges of science and the ideal of a unified science.

History

As a " founder " of the philosophy of biology - and zoology - applies Aristotle. His philosophy influenced Western thinking about organisms, their parts and their organization into the modern times. Excluded from the " natural things " are in Aristotle the non-moving things, they are the object of theology. Likewise -created works of art and irregular, ie random events, for Aristotle, not natural and thus not the object of his physics. Organisms are in Aristotle organized body, on the one hand differentiate into organs, and are conjoined by their functions. The shape of the body is its soul (see also the entelechy ) and therefore neither independent nor inseparable from the body. Functions of the soul are, for example, eat, breathe, grow and sleep. He can create a " scale of nature " (Scala Naturae ) and thus a classification of all living things and beyond the help of a high-value hierarchy of these functions. The soul it is that determines for each living a purpose. As Causa finalis ( final cause ) it acts directly in the direction of a self-realization of the individual. Aristotle anchored so that the cosmological teleological principle of Plato in the specific organism and thus in nature. Whether one can therefore speak of Aristotle " teleology " is judged differently in the philosophy of biology.

Aristotelian thought was widely influential for Western philosophy. In particular, the principle of final cause was taken over by the Christian theologians and extended to a proof of God. Only with the mechanistic thinking of the early modern period, the teleological approach was ousted because he was the emerging scientific method hardly accessible. Another departure from Aristotle was the very influential dualistic separation in body and mind of René Descartes. Everything that was not ( human ) mind, henceforth "body" and thus the same scientific method was available. The dissection that the soul functions between living things and non-living world established by Aristotle, were meaningless. In the wake of mechanistic thinking, many discussions revolved around the question of how the apparently obvious otherness of the creatures might still be explained.

A keen observer of biological research of his time was Immanuel Kant He is particularly interested in the position of man in nature, whereby models and analogies from biology to his philosophy were more important than those from the physics. To enable the scientific experience in the first place, Kant uses the " expediency " as regulatory and structural principle. Like Aristotle, Kant defined the usefulness to the basic principle of the living being itself, not as a constitutive element of nature. Only this tool, the judgment creates an organizing principle in biology. Kant does so in his philosophy on self- biological analogies and models. Not least because he had a big influence on contemporary biology.

But the problem of the distinction between animate and inanimate nature was still hotly debated. A "life force" should be the real driving force of the higher evolution of species. Around the turn of the century to the 20th century were the approaches of Hans Driesch ( entelechy ), by Henri Bergson ( Élan vital) or Pierre Teilhard de Chardin ( Omega Point ) widespread and popular within and outside academia. Less, because suddenly you are no targeted processes more perceived, but because this approach was barren for the current scientific method, the decline of this vitalist positions was initiated. The so-called neo-vitalism was refuted by the work of Sven Hörstadius and John Runnstrom ultimately. For the history of philosophy of biology, however, this episode provides an intuition as general philosophical concepts go into professional programs of scientific research and how meaningful is a clear separation in analytical propositions of science theory and empirical propositions of biology.

After the unprecedented upsurge of modern physics and the end of vitalism in biology, the problem of differentiation to the question of the differences between physics and biology was. Were discussed holistic and process- philosophical approaches. Alfred North Whitehead moved the (life) processes of the organism in the center of his metaphysics, whereby the elements of the physics of it are virtually derived. This organicism has subsequently more difficult to reconstruct the elements of physics and therefore unfolds until today little concrete research. Samuel Alexander also tried to cultural values ​​in his holism to integrate, the living creatures and especially humans a central mediating role in the " planes of existence " plays. Richard Hönigswald, both physician and philosopher, developed in the 1920s as part of its realistic criticism a conception of the organic as a self-regulating system that is compatible with the more modern approaches, such as evolutionary epistemology and has also approaches a philosophy of culture.

Enforced but has the mechanistic- naturalistic conception. Joseph Henry Woodger (The Axiomatic Method in Biology, 1937) sought in the sense of logical empiricism of the physicalist his time to reconstruct the biology axiomatic. However, it remained at this a try, since the hypothetical- deductive reconstruction is poorly applicable to the disciplines of biology and is completely rejected. The interest of philosophy focused at this time on the physics and psychology. Two developments in the mid-20th century, the formulation of the synthetic theory of evolution and developments in molecular biology, it also helped the philosophy of biology to an upswing. At least since the 1970s, it has established itself as a widely ramified and serious sub-discipline of philosophy and biological problems are among the most important in philosophy.

Analytical Philosophy of Science

Ontology and epistemology

The central importance of evolution for modern biology has often been noted. Under their influence, the inanimate and especially living nature be regarded as something mutable. In contrast to the essentialist concepts that for centuries dominated Western thought, this is a radical upheaval. War in Plato nor the timeless "idea" of the real and the concrete forms which it derived, then in the context of biological evolution the concrete, temporal, and variable objects the real.

The number of observed object classes in biology in relation to the natural sciences, physics and chemistry, however, much higher. While the physics knows only a few dozen classes of objects such as stars, planets and atoms, there are in the various sub-disciplines of biology hundreds - such as organs, cells and species. In addition, they usually have characteristics such as heterogeneity, complexity and dynamics. The more difficult is the determination of the ontological and biological status of the individual object classes. It also raises the question of what are the basic objects in the sense of a scientific approach. Thus, the cell was for example with Rudolf Virchow " elementary organism " and since the second half of the 20th century, the focus is on the genome. The most influential formulation of an ontological dualism of René Descartes enabled as a result also a methodological separation in a material and a spiritual world. In this tradition, the physics experienced a hitherto unparalleled upswing and oriented on this scientific theory is based on a materialistic and naturalistic understanding of nature. However, the resulting continuous and currently prevailing understanding of the philosophy of science at the so-called logical empiricism is oriented, which makes ontological questions under the suspicion of fruitless speculation and therefore largely excludes.

In search of basic laws and fundamental structures tries to return the properties and characteristics of all objects of research on regularities of these structures. An ontological reductionism, ie a materialistic monism is now generally accepted. When considering many biological phenomena but encounters a theory reduction to their limits as well as non- material phenomena such as perception, consciousness and the will be addressed in various fields of biology such as sociobiology or neurobiology. While there are several approaches but still no convincing solution for the description and explanation of intentional and phenomenal states. Goal of many considerations is a physicalism, which implies no reductionism, otherwise no independent biological theories would be possible. A radical mechanistic physicalism ( " everything is physics " ), however, would not only make the distinction in biology from physics impossible. Such a physicalism is untenable for that reason alone, some philosophers, as it would deny the difference between life and death. The situation is similar with the obvious difference between the animate and inanimate nature. This contrast was thereby mitigated, that the predominant organism model joined the program model in biology from the machine model. The advent of cybernetics and not least the discovery of the genetic code moved functionalist information models at the center. The highly complex organism can work from this perspective as a whole. The coexistence of mental and material phenomena is discussed today mainly based on emergenztheoretischen positions or the concept of self-organization.

Methodology and Experiment

The research methods used in the biological sub-disciplines are just as extensive as the investigated object classes. They range from engineering methods in biotechnology, narrative techniques in neuroscience and influences of historical sciences in paleontology to bioethical issues. Explanatory theories in the fields of biology are more like general rules with multiple exceptions and rarely the validity claim of universal laws as they are, for example, formulated in physics. Important quality criteria of scientific theories such as the declare value, predictability and repeatability are limits in biology.

Reduction

An important question is whether it is possible theories in biology to physical ( and chemical ) reduce theories. The classical approach to a theory reduction by Ernest Nagel ( 1961) is most philosophers too far as fundamental terms such as " life " does not have been reduced. In most cases no need for additional physico-chemical theories to explain and support is determined by bioscience statements. For example, Philip Kitcher denies based on the Gendefinition that the Genbegriff of classical genetics can be traced back to the Genbegriff of molecular biology and in particular cites three reasons: 1 The classical genetics and molecular genetics are not in accordance with the conception of theories that used nail. 2 The term "gene " of the classical genetics can not be described in biochemical terms. 3 Each derivation of a theory would be non- explanatory. Reductionists argue, however, that the task of deriving all biological theories of physico-chemical, only a practical, but is not a fundamental problem today.

In contrast, a " Constitutive reduction", ie a takeover of the theories and concepts about the material composition of organic and inorganic things, widely accepted in biology and philosophy. Furthermore, theories in biology are usually formulated probabilistic and do not describe a strict determinism, as in classical physics or chemistry. But it is not a blind eye that probabilistic theories can be strictly reductionist, as showing the genetics of Mendel. Both these that yes a cornerstone of the synthesis, as well as the synthetic theory of evolution must be classified as reductionist as long as the latter in the second half of the 20th century held to a strict Genzentrismus, the evolutionary events largely incidental to the chain of reasoning genetic mutation - natural selection and adaptation in the population cut. Only slowly succeeds in today's theory of evolution, to free themselves from narrow perspectives of this kind. Today's theory of evolution treated far more evolutionary factors as the Syntheses and sees evolution increasingly in interdependent contexts. This opening is room for complex theory methods. This will among others, so in the fact that the considered living systems themselves and the relationships between them, processes of nature are highly complex, open and individually. Thus, biological theories are usually formulated with the openness to exceptions and claim only a limited application and scope. This contrasts with other groups that have started based on modified proposals for the framework conditions of evolution with the addition of mechanisms of development ( evo-devo ), environmental influences, multilevel selection, niche construction and large system transitions to explain the more complex scenario with modern methods

Methodological critique

All marks of the living, so the object of investigation of the biology meet, also on the observer. Therefore, all questions can be addressed in biology from the anthropomorphic indoor or outdoor technomorphic perspective. From the choice of perspective and the scope of a statement depends. In a broader sense, any biological research on historical, social, economic, political and anthropological conditions is established. In a contextualist approach methods and the knowledge of the biology of these perspectives are examined. Methodological requirements are as a result of the desire for control, manipulation and forecasts.

The positivist empiricism logical focuses on theories and models, observations and pictures, however, have little value. In the biology of these methods are, however, particularly important. From the hand-drawn illustrations of Ernst Haeckel to the current imaging techniques in neuroscience the role of representation in biology is always an important and sometimes controversial subject of philosophical reflection.

Experiment and Experimental Systems

Although its central importance in biological research undertook the experiment in the epistemological analysis has long been a Schattendasein.Es has shown that contrary to the usual view that experiments to test existing theories, the most and the most fruitful experiments themselves have an exploratory function ( so-called exploratory experiments). Especially in the context of biological research raises the experiment as an artificial, manipulative interference in the natural processes represents the nature is thereby reduced, separated and "conveys in apparatus " as a rule For example, with the electron microscope technically no vital observations ( observations of living structures) possible. An idealized control situation in the biological experiment is not always possible. This is especially true in ecology and in the behavioral sciences, but also in molecular biology.

More special boundary conditions of biological research topics such as the uniqueness of living things, the historicity of evolution as a whole or the need for special environmental conditions for model organisms, as well as cause particular circumstances and limitations of biological experimental systems. The same applies to experiments on inanimate objects ( in vitro experiments ) as are common in various aspects of biology. They raise the question of whether they allow conclusions on living systems, but also whether the Experimental Biology actually concerned with the living world.

Basic Problems of Biophilosophie

The main themes of the philosophy of biology can be roughly divided into three areas. The central role for the analysis of evolutionary theory, its foundations, statements and consequences. What are species, how can you define it and how scientifically classify and organize. A second group of issues revolves around the reduction or the ratio between the physics ( and chemistry) and biology. To this end, there are many technical and analytical problems, which blend into the third group of problems: the attempts to rewrite so special about living things in nature and moor of criteria.

What is life?

Life is defined today as a system of properties in scientific biology. So lists Georg Toepfer two dozen historical - and after all six since 1980 continuous - definitions which differ more or less. The terms life and living beings are not biological but ontological concepts. For the cognitive interests and questions of biology, both terms are also irrelevant, if you want to explicitly refer to it, we now speak more of " living systems ".

The discovery of the entropy of the mid-19th century resulted in more than a century to the widespread belief that the order of living things ultimately can not be described and explained in terms of physics. The physicist Erwin Schrödinger described in 1951 the concept of " negative entropy ", now also negentropy. After that " feed " of living things quasi negative entropy; continuously when power is supplied to keep the critters their state far from thermodynamic equilibrium upright. The ideas were later elaborated so far as by the work of Ilya Prigogine, Isabelle Stengers and Manfred Eigen, that entropy and life today represent no more conceptual contrast and the principle of order of life is understood in a very general level.

Status and structure of the theory of evolution

Importance of the theory of evolution

Today's synthetic theory of evolution is very different from the known, mathematically formulated theories from physics and chemistry. The attempt to formulate them according to a logical empiricism, also has some difficulties. If we identify the " natural selection " as a fundamental axiom, it is difficult for the concept of "fitness" deduce, on the one hand a general law can not be seen, but on the other hand, a relative definition is trivial. Nevertheless fitness is the most important parameter for mathematically modeled population biology. The current status in the philosophy of biology to this problem is the view that a higher fitness only increases the disposition to produce viable offspring. If you continue to the large number of sub-areas of evolutionary theory, such as paleontology, comparative anatomy and biogeography, and the immense number of different findings and concepts into account, it becomes clear that an axiomatic ( re) construction not in the sense of logical empiricism for the theory of evolution is possible. In this respect, the epistemological status of the theory of evolution in the philosophy of biology remains unclear.

The value of a scientific theory can be given based on several criteria. First, one can distinguish in practical and theoretical value. The practical value of a theory consists on the one hand to make predictions in possibility. For the theory of evolution is widely believed that they do not or hardly permits predictions. Reasons for this are the randomness of events differ in importance, uniqueness of the individuals involved, the complexity of the systems and the occurrence of so-called emergence - that is known systems spontaneously develop new and unpredictable properties.

Also the benefit of the theory of evolution is represented differently. The practical utility of a scientific theory can be divided into the ability to create forecasts and their technical applicability. In the Darwinian theory of evolution is now doubted that it allows correct predictions. The will but assert that by at least retrodictions, so explanations of past developments are possible and limited in some cases even correct predictions were derived. But is emphasized rather the intellectual benefits of the theory of evolution. The theory of evolution makes no Allaussgen. Due to the large number of possible evolutionary factors and their random character, the Darwinian theory of evolution is not a deterministic theory. There is also no single canonical form of the theory of evolution, to which all biologists refer alike. The importance of evolutionary theory lies in its role in the modern scientific worldview.

Challenge Evo - Devo

The Evolutionary Developmental Biology ( Evo - Devo ) has taken up several issues of the synthetic theory of evolution and made ​​clear. Thus, first the concept of natural selection is geared towards adult organisms and their genetic constitution. These two components - adult individuals and genes - to explain in interaction with natural selection and adaptation every evolutionary change.

But in the individual development genes lead only under certain conditions to the expression of a characteristic of the phenotype or they are no longer as initiation factors for the phenotypic change, without being able to adequately represent these. All " mediating " conditions are assumed. Furthermore, in most multicellular living organisms, all cells have the same genes, but they can develop completely different. The classical theory of heredity can not explain the inheritance of developmental factors. It seems that the gene expression and its conditions for the evolution are more important than the genes themselves also recognizes Evo - Devo autonomy of cells and cell structures capable of self-organization. In such an environment, minor genetic or environmental stimuli can the system development using threshold effects and means of helping its high Intergrationsfähigkeit to larger variations. In the words of Gerd B. Müller: minor faults (mutations, environmental factors ) can point to a higher level ( embryonic development ) great, but integrated effect (variation ). The consideration of the individual development thus leads to reject the gene as the fundamental unit of information and evolution. Evolution is conceived within evo-devo as a variation and replication of entire life cycles. The genes are only one element of many.

Manfred Laubichler analyzes the methodological and epistemological differences between evolutionary biology and developmental biology and find countless evidence standards and research methodologies, different notions of causality. So evolutionary biology is looking for ultimate causes causes, so for the benefits of adjustments and the reasonableness of selections, while the development of biology is based on immediate proximate causes that show up in the ontogeny.

The claim of evo-devo in evolutionary theory goes even further: The synthesis is seen in their populationshtoeretischen expression as being " statistically descriptive " while with the knowledge of evolutionary developmental mechanisms a more and more " mechanistic causal reasoning " picks.

What is the significance of evolutionary developmental biology total plays is controversial even in the philosophy of biology and evolutionary biology. The positions range from rejection of the dominance of the synthetic theory of evolution, the search for a theory extension or supplementary theory to replacement by a " development- based" theory of evolution. What is clear is that a purely static, gene- trated approach to the explanation of evolution with developmental biology can not be reconciled.

The unit of selection

The founder of the theory of evolution, Charles Darwin and Alfred Russel Wallace were in the question of where the natural selection attaches, does not agree. While Darwin was looking at the individual as the sole unit of selection, Wallace argued that selection takes place at the level of groups. After nearly 100 years, a group selection in biology was thought possible, with the development of molecular genetics in the 1960s came new arguments to it. Since only the individual develops directly from the genes was evaluated not only as the argument for the selection of the individual organism, but the genes themselves been proposed as the selection level. As a result, the subject was in the philosophy of biology is one of the most important and has been widely discussed. It was found that the " gene selection " many examples in nature could not adequately explain. In particular, it fails in the explanation of systematic fluctuations in the frequency of genotypes. Likewise, there must be a clear causal chain between genotype and phenotype, so that a reproductive success directly affects the genes. Elisabeth Anne Lloyd struck in 1988 propose to adopt the criteria for possible selection units in more detail. Thus, a unit must interact directly with their environment. Most scientists came then to the conclusion that a gene selection is untenable.

Beginning of the twentieth century was reinforced discussed the question in evolutionary biology, if there are altruistic behavior between unrelated individuals in the animal kingdom and how its existence could be explained by using the theory of evolution. Although Darwin himself already brought the so-called group selection into the game, but his classical doctrine of natural selection knows only the individual as a reproductive unit. With the development of molecular genetics in the 1960s, the genes were identified as the unit of selection. As suggested by George C. Williams 1966 " use " the genes chromosomes, cell structures, and the whole organism for successful reproduction. The individual is thus only the outer appearance, the actual subjects of the selection are the genes. Only from that time began a systematic study of this question in the Biophilosophie. So put Stephen J. Gould (1980 ) and Robert Brandom (1984 ) found that genes are "visible" to the outside and not be virtually " hidden " by the organism. David Hull ( 1981) was then first clarify whether the carrier units of selection can be thought of only as replicators or need to interact causally with their environment to reproductive success. In the second case, genes would come as a carrier hardly in question.

Elliott Sober used the example of a dominant-recessive inheritance, in order to show that genes can not be causally involved in natural selection. In return, he theorizes a pluralistic and hierarchical view of selection, which is the predominant today. Thus, there are several " levels of selection", and the interaction with the environment takes place at different levels. However, it is still controversial, as mutually influence these " levels of selection" and whether they are at least partially reducible to each other. (Sober, 2003). With the advent of evolutionary developmental biology also the view has prevailed that the visible manifestations of the organism (phenotype, manifest traits ) not only are the product of genes, but develop from the interaction of the DNA, other molecules and cell structures, and environmental influences.

Classification

The question of the ontological and epistemological status of species is frequently discussed in the philosophy of biology. The idea that there are clearly separate species is provided mostly unchallenged in biology. On closer inspection, however, all attempts at a unique separation with different difficulties are connected. First we have to clarify whether species or all taxa can be viewed as a mathematical or geometric class. Consequences would include that the objects abstract, must have unique properties and that classes are defined by their objects. However, the idea of static classes is contrary to the idea of ​​evolution of the varying species. With the concept of family resemblance Ludwig Wittgenstein, however, has formulated a way how to by blurred - can classify property definitions as well - and thus more realistic.

Ernst Mayr defined species as a bunch of populations or communities reproduction. A biological species is therefore the sum of its concrete variants and no " ideal type " or average. Instead of descriptive features, the concept of the origin and existence conditions used to differentiate. This definition has its limits when one considers, for example, organisms that reproduce asexually, or if you want to classify extinct organisms. Mayr's definition of species as reproductive communities was nevertheless a great success and sat largely in biology through. Equally important in evolutionary biology is a division of the species by their lineage relationship (see phylogeny ). Today in biological practice, the determination of species is based on morphological characteristics supplemented by a consideration of their origin story (illustrated by homologous genes and DNA sequences).

1974 surprised the biologist Michael Ghiselin with the proposal to replace the abstract, essentialist and mathematical class concept through a spatio-temporal individual. Species are therefore to be regarded with an individual life cycle and concrete relations in their ancestry and cohabitation more like organisms. The disadvantage of this concept is, however, that the application of mathematical and numerical methods in particular to determine the species ( "numerical taxonomy " ) from this point of view is doubtful. Moreover, it is impossible that species after the extinction occur again. The debate about the use of concepts and criteria for classification is often performed under the terms " definition of species " and " species problem " with changing priorities and continues to this day.

Organism models and model organisms

Living beings are determined by Aristotle as everything else by matter and form. The "form of organisms " is the division into organs. Form and nature of the organisms in accordance with the soul, whereby the difference between the animate and the inanimate over the animate and non - animate is determined. The soul uses the body as a tool. This functional tool analogy applies both to individual organs as well as on the body as a whole.

René Descartes in the 17th century took a radical turn by itself zusprach the assets active activity of matter. Across from her, he sat down to the human, thinking mind; the concept of the soul as shaping, active principle disappeared almost completely. Life is in Descartes to automatism of the material and the machine analogy to the prevailing model organism. Since then, the organism models in the biological sciences are generally dominated by technomorphic metaphors. Today's attempts to expand the machine analogy to a machine theory, have not prevailed, because living things blow up all machines metaphors with their skills. To express the homogeneity, regularity, self-similarity and order of living things, and the crystal model as part of the cell theory by Theodor Schwann and Matthias Schleiden Jacob became popular in the 19th century. In contrast to the machine model it evokes no idea of a planned, purposive action, because it points to an inorganic context. Theodor Schwann used the crystal analogy for cell formation, but the limitations of the model was always aware. In this compilation, we must not forget that the term "organism" itself is a " concept of the organism ". It was introduced in an effort more to point back to the special position of living in an increasingly mechanized world in the early 18th century by Georg Ernst Stahl.

To describe organisms and populations in today's scientific theories that biology requires formalized models. Based on a scientific model building organisms are described as physico- chemical systems. However, since both the physics and chemistry does not reflect the property of the vitality of the organisms, a purely mechanistic approach is untenable. Another approach in modeling can be found in the so-called design morphology. Organisms are regarded as mechanical energy converter. Besides physiological aspects, the structure and form of organisms, but more particularly described its operation based on analogies with the hydraulics. Constructional models have been proven in research practice already common.

With Erwin Schrödinger's book " What is life? " ( "What is life? ", 1944) found the idea of the information input into the biology. Carrier of this information is therefore of the genetic code. Now prevail analogies from the computer and information technology. Examples include translation, transcription and the concept of " genetic information " itself

Just as organism models of biological research provide starting points for questions and theories, model organisms are central for experimental research. The hope is to find general statements about features, species or even life itself based on a very limited selection of research subjects. To what extent such an extrapolation is justified is debatable, depending on the individual case. The use of a specific model organism always reflects the research situation. So it would be Gregor Mendel not been possible to derive its rules of inheritance with horses, turtles and many other species experimentally. The same applies to the fruit fly Drosophila melanogaster and its significance for genetics and recently also for the development of biology. Model organisms in research labs have as part of experimental systems, however, other features. As always, an expense must be operated to produce the living conditions of organisms and preserved. The experimental situation is so controlled and manipulated inevitable.

Functions and teleology

In addition to the question of how it is in biology are also interested in the question of why. For example, one may ask how a human thumb works, but also why it exists at all and what purpose it serves. So Convincing function attributions explain not only the function but also the existence of the functional carrier itself during either finalistic (based on a goal or purpose), speculative answer otherworldly forces or an intrinsic goal-directedness questions about the purpose of the questions on the specific function could be partially answered better organs and other things with the progress of experimental technique. At the same time it remains insurmountable difficult features to explain phenotypic characteristics that want to serve a purpose in the past, which no longer exists today. However, the feature is available. With the development of the theory of evolution and in particular with the theory of natural selection was hoped that the declaration of purpose questions using a mechanistic and naturalistic approach. So the concept of teleonomy was introduced into the philosophical discussion to explain adaptations as causal, coherent consequences of natural selection. The targeted, formative principle is a part of a biological program. The usefulness is ultimately always the conservation of the species or the individual. Use of natural selection, this is then part of the biological program.

These statements but must face a variety of criticism. Firstly, this definition is criticized for being circular, because it disregards the possibility that there may also be programs that are not targeted. On the other selection is directed only to the past, she "plans" not in the future. Carl Gustav Hempel turned to 1965 that the functional effect of a feature is always selected only for the future. Thus, the historical evolution will separate from the functions. Furthermore, it was indicated that selection- theoretical approaches can not be responsible for a specific purpose, because - even hypothetically - unselected things can fulfill the same purpose. On the other hand, there could be features of an organism such as organ failures that are not referred to as a function, but are nevertheless genetically fixed.

Teleonomic explanations deny not the usefulness of things, but put them as a result of natural processes dar. so long as the term teleology is merely used descriptively, there are some philosophers no reason to use another. Thus, a teleological language and teleological methods, despite all the criticism, still part of biology. In particular, in paleontology, there are many examples where teleological heuristic approaches in research are of great importance. As the only valid form of teleology in biology an intentionalist interpretation is considered to be merely symbolic representation of a purpose and thus be the cause of an action.

Gendefinition

Molecular genetics versus

The Genbegriff is defined completely different for molecular biology on the one hand, and classical genetics, biological evolution theory and population genetics on the other side. In the context of classical genetics of Genbegriff serves as a formal unit, by means of which feature changes can be generally depicted in subsequent generations. Furthermore, essential to the ideas of genes was the separation in germline and " Body Substance " by August Weismann and the conceptual distinction between genotype and phenotype. In molecular biology, the genes are, however, considered to be a physical and chemical substance as a part of the deoxyribonucleic acid ( DNA), the carrier unit of a " genetic information " is the same time. Result, both the stability and variability of genes as well as their reproductive capacity were plausible. This range of possible fragmentary determination of the gene can be used, depending on the experimental system in the biological sub-disciplines are still a number of definitions. So there are in biophysics, biochemistry, molecular genetics, evolutionary biology and developmental genetics different but not mutually inconsistent definitions.

The incentive to find a cross- disciplines and general definition for a gene was never very large. Today, two approaches can be distinguished. One is trying to establish the gene based on static, spatial and structural conditions as part of the DNA, the other approach determines a gene using the functionality of the results ( eg, proteins ) as unit of heredity or functional unit. It seems, though so that more recent findings with other model organisms make a further simplification and consensus rather unlikely.

Genetic information, genetic program

For Godfrey -Smith ( 2000b, 2003), the concept of genetic information is justified by the role of genes in ontogeny. In contrast, they are merely metaphors without serious theoretical contribution to other authors, philosophers and biologists. The image of the genetic information can then not be understood in the sense of a mathematical information theory. Two sequences of base pairs in the DNA may have the same mathematical information content, but differ significantly in their " genetic information ". Thus, although the quantity and coding is considered, but the meaning and function of the genetic information hidden consistently.

Influences biological theories on the philosophy

Since Aristotle findings, methods and theories from the teachings of the creatures have found their way into philosophy again and again. Thus, the concept of evolution provides a central historical context for all empirical sciences (see Chemical Evolution, Sociocultural Evolution). The application of evolutionary theory to the question of the cognitive process itself led to the establishment of the so-called evolutionary epistemology. After the basics of possibility of knowledge by the phylogenetic development ( the people ) have emerged and can be thus described, analyzed and evaluated. This interpretation touches on many philosophical issues such as the question of the recognition of the reality and the question of the quality and the value of a knowledge which is completely determined in this way. Has evolutionary success after the evolutionary epistemology have a direct connection with the truth in the sense of a correspondence theory, and implications for the history of science, didactics and anthropology.

There are also attempts to use biological evolution theory on the ethics and aesthetics. Both approaches, however, are very controversial.