To illustrate the way domain categories can influence the way we thing consider the following: many philosophers of science believe today that there is no single factor demarcating science from other intellectual pursuits, if this becomes widely accepted then any clear demarcation between science and the humanities becomes untenable. ‘Geography, like biology and sociology, is a huge and loosely defined field (so loosely defined, in fact, that since the 1940s many universities have decided that it is not an academic discipline at all and have closed their geography departments)’.[1, Morris, Why West Rules] A prominent historian has suggested that the word ‘history’ is a pretentious way of talking about human behaviour in the past, in which case the subject History might be better treated as a sub-discipline of a more inclusive domain like ‘animal behaviour’ or ‘sociobiology’ which could also include subjects like human psychology, political science and sociology. Maybe we should include anthropology and archaeology here. Would economics and political science be more logically considered as sub-disciplines of sociology and therefore of slightly lower rank? If biology is really about physics and chemistry then maybe it would make more sense if deliberately taught as a sub-discipline of these subjects? Then there all the hybrid disciplines like astrobiology, biophysics, biogeography, biochemistry, geochemistry, social science, scientific humanities. Old arrangements are clearly archaic relics but the question now is whether subjects academic disciplines should simply be a matter of convenience or reflect some coherent rationale or, indeed, the world.
In practical terms a restructuring of the sciences is unlikely. Scientists today tend to work within their own fields, each with their own procedures, principles, theories and technical terms, resulting in physical and intellectual separation that resists fragmentation or combination. Academic territory, whether of theoretical knowledge or physical space, will be defended. Real or imagined disciplinary imperialism is a factor to be noted in any analysis of reductionism.
The point is that we take our existing taxonomy of domains of knowledge for granted when there are no unambiguous criteria on which our classification is based. Which are the wholes and which are the parts? Are our classifications a matter of subjective convenience and utility or are they sometimes founded in the objective nature of the world as we might suppose for science?
Principle 1 -Reductionism challenges the boundaries (criteria) that we use to distinguish one domain of knowledge from another, asking if we can devise scientifically acceptable criteria for dividing up the natural world into domains that more closely mirror the world itself.
Principle 2 – Classifications proceed (like reduction and explanation in general) by abstraction – by simplifying complexity. Classifications also establish relations between items and in so doing they contribute to theory-construction, description, explanation and, importantly, prediction.
There does appear to be a great opportunity for consilience here – a reconsideration of the way we both represent all knowledge and teach it I our schools and universities.
If we accept Principle 1 – that no piece of matter exists in a more fundamental way than any other – (all matter is ontologically equal – either it exists or it does not) then can we make use of the scale units of various disciplines?
The important points is that no domain of knowledge or scale that is ‘in reality’ (ontologically) more fundamental than any other but talk of ‘scale’ and ‘domains’ now gives us some useful categories to work with.
Principle 3 – Explanations in one particular domain do not take precedence over those in any other – although some explanations may carry higher degrees of confidence than others and some domains may contain more high confidence explanations than other domains
Consider the material reality of the following: molecules (chemistry), organisms in general and ant colonies in particular (biology), historical events (history), society (organisations, trading blocs, communities). There seems to be some abstraction going on as we move through this series: we are passing from the language of brute matter into worlds with some conceptual loading. We will return to this later – suffice it to say at this stage that the status of these units is more fuzzy.
THE UNITY OF SCIENCE
A universal language
At present science is divided into disciplines with effectively different languages and objects of study. Wouldn’t it be easier if we abandoned all talk of scales and levels and spoke in a language where all units were comprised of the same thing? This would be like suddenly enjoying the efficiency of having a world currency instead of many, or a single global language instead of the confusing babble of different and often uncomprehensible languages of many nations? Instead of the diverse terminologies of sociology, politics, biology and chemistry we could have one single language – that of physics.
This may be possible in theory but could never eventuate in practice in spite of some unification. In theory it may be possible to describe cell division in molecular terms but in practice the translation of structures, variables and pathways of interaction would be phenomenally and prohibitively complex.
We can see here how our cognition is coping with complexity by imposing ‘scales’ on the world. Scales close to one-another, like physics and chemistry, operate in similar ways and use similar terminologies so explaining characteristics of one in the specialist technical terms and theories of the other may not present major problems. We can easily understand the close connections between molecular biology, biochemistry, and genetics. But as the difference in scale units increases so too do the difficulties in the translation of one domain of knowledge into another – and there is a corresponding decrease in the benefits of doing so. Explaining the major concepts and theories of political science in terms of atoms and molecules appears, at face value, absurd. Predicting weather patterns is difficult enough in the terms we use today without breaking our explanations down into the causal interrelationships of every molecule within the system – even though, in theory, this may be possible. This is not because this is logically impossible but because of our cognitive limitations: we do not have the computing power to do this and so find simpler modes of mental synthesis.
From this we can derive two general principles: On the other hand the relationship between biochemistry, molecular genetics, and chemistry is clearly and so in this case ‘reduction’ is much more credible. On the other hand the general use of physicochemical or molecular language and ideas in describing the generalities of ecology doesn’t really make sense. The question ‘Do we only need one scale or ‘level’ to explain everything’ is not so much a question of feasibility, more a question of utility. We need the cognitive convenience of talk at different scales.
THE METHODOLOGY OF REDUCTION
It is one thing to speak of reducing theory A into theory B but quite another to carry it out. In fact there is a subtle distinction between the ways that this can be done – whether it be done by translation, derivation, explanation or some combination of these.
One way of expressing the methodological aspect of reduction is to consider the reduction of one knowledge domain or theory to that of another: maths to logic, consciousness to physics and chemistry. This may be done by: translating key concepts of A into those of B; deriving key ideas of B from those of A; or when all the circumstances of B are explained by A.
The attempt to translate the terms of one discipline into those of another has proved too problematic to be realistic. Even where terms apply to the same object they may have slightly different independent meanings.
It has been agreed that in terms of ‘matter’ an organism it consists of molecules. It has also been suggested that molecules are not ‘fundamental’. After all, we could also say that organisms consist of cells, tissues, or organs without threatening their physical ‘reality’. Indeed, rather than looking at ‘wholes’ that are larger then molecules we can be more fundamental by describing an organism in terms of its sub-atomic particles. But at this point it will probably be argued that subatomic particles are not informative – it is the way they are organised into functional parts and the relationship between these parts that is important.
We now need to ask how we can translate one scale, level, or knowledge domain into another. How do we translate language about molecules into language about cells into language about tissues, into language about organs, into language about organisms. We must also ask whether the ‘reality’ of the units chosen.
Philosophers have asked whether the theories or principles of the biological sciences can be demonstrated as logical consequences of the theories of the physical sciences?
In the 1960s American philosopher Ernest Nagel (an early logical empiricist philosopher of biology along with Carl Hempel, and followed in the 1970s by David Hull) suggested a theoretical in-principle model for this logical reduction. A target theory was deduced from a base theory via bridging laws. This has proved difficult although it is still pursued in potentially comparable fields of study, one example being the reduction of classical Mendelian genetics to molecular biology. There was a messiness and imprecision because concepts vary and there are problems over the equivalence of terms, and target theories need subsequent modification.
If nature is indeed arranged hierarchically then we can perhaps take advantage of the principles of hierarchical classification: inclusivity, transitivity, association and distinction, and exclusivity.
Supposing the successful reduction of biology to physics and chemistry why not continue to, say, sociology. Would sociologists find it of any use addressing the consequences of the protestant work ethic in physicochemical terms?
We fall back on the principle of explanatory utility: biological terminology is generally more useful than physicochemical terminology. For the most part there seems little to be gained from a statement like ‘leg = block of physicochemical processes X’. There will, of course, be times when we need to know the chemical composition of a leg, and nowadays in many circumstances we might want to think of a gene in chemical terms rather than as a blob of matter like a bead on a string, so a reduction here is useful. In this sense reduction is neither in some way mistaken, misrepresenting, or inadequate – just totally impractical.
For example the word ‘cell’ in biology when used in a general sense is a useful biological concept but it can refer to many different kinds of physical objects and no individual cell is uniquely indispensable: we cannot say, for example, ‘x is a cell iff x is ‘physical expression’. That is, different structures can produce the same outcomes as when compensatory adjustments are made if brain damage occurs (a phenomenon referred to as multiple realization or degeneracy). Some form of physicochemical shorthand expression might convey the general meaning ‘leaf’ but individual leaves will have unique molecular structures. In general the vocabulary of biology does not map easily onto that of physics.
Interaction between levels or scales
In providing explanations and ‘reducing’ complexity we can place undue emphasis on particular ‘levels’ or frames of explanation or scales. Society is not always concerned with large things and physics small things.
Insofar as science is concerned with the structure of the natural world then it encourages the improved understanding of the structure and behaviour of matter. Simply stating something in different words is unproductive unless something is gained in the process.
Principle 3 – reduction is only scientifically useful when it improves our understanding by providing a better explanation (by giving a necessary and sufficient answer to the question being posed). Provided scientific units are credible then the scale we use for explanation is simply a matter of utility.
Probability (degree of confidence)
To some extent we measure the scientific merit of an explanation through our confidence in in its predictability – the probability of a particular outcome. However, if we predict the likelihood of the sun coming up tomorrow morning as being very near to 100% and the likelihood of climate change causing a rise of 2oC over the next 50 years as 70% can we say that one statement is more scientific than the other? It would seem not but this draws attention to the fact that there do seem to be greater degrees of certainty in (parts of) some domains rather than others. In cases like this we understand a scientific explanation as being the one that is the best we can achieve at present.
REDUCING BIOLOGY TO PHYSICS & CHEMISTRY
Why shouldn’t biology become a branch of the physical sciences? And in exactly what way can biological organisation be something over and above the molecules out of which an organism is composed?
In some respects it already is since as lumps of matter organisms obey many of the laws of physics, such as those of gravitation. And we can recognise how much of genetics has moved from the domain of general biology into the world of biochemistry and molecular biology. Since the human body undoubtedly consists of physicochemical objects and interactions perhaps we can envisage a super-computer that one day might be able to formulate a vast algorithm that simulates how all these molecules interact as the body goes about its daily business. But are there any problems that make the proposition theoretically impossible?
Because we can study both the brain and the gene in terms of molecules then for some biologists it might appear that we have, in the macro-molecule, a more fundamental level, scale, or source of unity. The question is whether such explanations are feasible, and if they are, whether the answers they give are informative or not. We are yet to resolve this.
Principle 7 – what is controversial about organic wholes is not their existence but the nature of their origins, their differentiation into parts, and the interaction of those parts.
Is there something about organic organisation and the complex interaction of the parts and their properties that defies reduction to explanations in terms of constituent physicochemical processes?
The biological theory of ‘emergence’ claims that this is so.
Biology & its link to other disciplines
Living matter is variable replicating matter that has the capacity, over many generations, to incorporate physical changes in response to influences from its surroundings. The variation that facilitates the persistence and replication of this matter is incorporated as physical change over many generations since changes that do not permit replication simply cease to exist. In mechanical terminology this is fine-tuning using feedback.
In biological terminology we have environmental adaptation by natural selection – descent with modification as a result of heritable variation and differential reproduction. Natural selection is the way we account for adaptive complexity and design in nature – the complex interplay of parts serving some function – and it is the process underlying the evolution of the entire community of life.
The process of natural selection introduces several crucial ideas:
1. There is a clear distinction between evolving and non-evolving matter: living and inanimate matter
2. Living matter cannot exist independently of its surroundings and therefore exists in a kind of organism-environment continuum
3. Natural selection gives a naturalistic account of the self-evident design we see in nature: it is the mindless way in which functional organized organic complexity, including humans and their brains, arose
4. Natural selection is a process that discriminates (selects) and which can therefore succeed or fail. Living matter has rudimentary ‘interests’ in the sense that some changes in the environment facilitate its survival and reproduction while others do not
5. ?, life ‘adapts’ to its environment (value and reason); thirdly, the interplay between life and inanimate matter as a kind of continuum.