Select Page

CONTEXT

See the general introduction to plants and people which discusses the context of these two articles on classification in general and plant classification in particular as they relate to themes discussed on this web site. The article here considers the way our minds operate on all the categories of experience before examining the way that we manipulate the categories of science in general and plant science in particular. It is suggested that our sophisticated methods of classification can be applied to not only plant to plant relations as in plant classification, but also applied more rigorously to the relationship between plants and humans, and plants and the environment.

Classification

Our minds are constantly – both consciously and unconsciously – selecting, ordering, and arranging the objects of our experience. It is this mental classification that helps us make sense of the world.

This article examines the foundations of all classification systems before looking more closely at scientific classification. A follow-up article will then examine the classification of plants, not in relation to other plants, but in relation to humans.

Understanding the foundations of taxonomy/classification allows us to make an informed assessment of the function and service provided by our current scientific classifications, including ways that they may be improved.

Classification begins as an intuitive or instinctive process in our minds, but it is also performed as a conscious process whose consequences must be explained and shared through the medium of language.

Mind

Eighteenth century German philosopher Immanuel Kant, contrary to the views of many of his contemporaries, argued convincingly that the mind was not a passive ‘blank slate’ on which a person’s experiences are written. Rather, the mind contributes to ‘knowledge’ by actively structuring our experience. Kant even outlined in detail what he considered the mind contributed to our understanding of the world – this being our setting of all our experience within a context of space and time (his transcendental aesthetic) and within certain logical structuring principles or ‘categories’ (his transcendental analytic).

The detail of Kant’s argument remains contentious but the idea that the mind frames our experience in various ways, is now widely accepted. To use Kant’s form of expression: the mind must have certain predispositions if we are to have any meaningful experience at all.

Since Kant, the whole field of psychology has opened up. It is now clear that our minds are constrained by our species-specific human biology in many different ways. So, for example, we do not experience everything it is possible to experience, all at once. The flood of incoming sensory information is subjected to our mental processing. The consequence of this mental processing is that we exist in a world that is unified, coherent, and meaningful . . . not a confusing maelstrom of competing sensations.

At least four aspects of this processing can be usefully distinguished. The mind segregates the world into meaningful objects (mental categories), focuses on a limited range of these objects at any given time, often classifying and ranking them into groups according to conscious and unconscious priorities. These four processes of segregation, focus, classification, and ranking are hard-wired in us as part of our biological make-up: we know this because they occur in all cultures and are, indeed, essential preconditions for operating effectively in the world.

All these processes seem to occur simultaneously. So, for example, at present my attention has settled on writing this article (my attention segregating my mental world into my computer screen and the classifcation and ranking of words etc.). My attention may, of course, be diverted by a visitor, or the desire for a cup of coffee as my mind responds to internal and external triggers. But, when these diversions are satisfied, my mental focus comes back to the computer screen as my attention returns to the selection (prioritization, classification) of possible words to use, their order within a sentence, and so on.

Clearly the ability to order the world in this way is an evolved and inherited biological characteristic, and therefore part of our human nature.

This mental processing, the ordering of our experience, is an important part of what we refer to as ‘reason’. It is worthwhile considering them in more detail.

Segregation

Segregation structures our world into meaningful representational units of experience (mental categories), both those of cognition (concepts), and those of perception (percepts). The fact, for example, that our minds convert a field of colours, textures, and tones into meaningful objects like cars, people, trees etc. is an amazing mental feat that we all take for granted. The kinds of categories formed by our minds are species-specific (allowing us to communicate through language) as determined by our evolutionary history – they are our human ‘reality’. 

Focus

The mind not only fragments experience into meaningful categories, it also focuses our attention on a restricted range of these categories so that, at any given time, our attention consists of a foreground – the focus of attention – and a background of available categories of which we are not immediately aware.

Classification

Classification (as used here) is a convenient term for the processing of initial categories or segregates. Segregates are combined in various ways to become further categories in a complex system of interrelated groups and sub-groups, parts and wholes, all available for further mental processing.

Categorization may proceed intuitively as my attention processes sensory input. But when categorization becomes a crucial part of the conscious and deliberate organization of knowledge within the cumulative social process of collective learning, as occurs when we group animals and plants using carefully considered selection criteria in scientific way, we call this form of categorization ‘classification’.

Rank-value

Categorization may be based indifferently on the similarities and differences of categories – as when I note fruits and vegetables at a market. However, categories are frequently not only distinguished one from another, they are ranked in some way relative to one-another (valued, prioritized, specially selected) based on our needs, desires, purposes, and reasons – as when I am shopping specifically for strawberries and a cauliflower. The ranking or prioritizing of objects relative to one-another I call rank value.

For us to share with one-another the categories we form in our minds, we must communicate using spoken, written, printed, or electronic language. In this way the refinement of our shared categorization can become part of both our individual and collective learning.

Language

The Scientific Revolution drew attention to Aristotle’s preoccupation with logic and order, placing a new emphasis on science as an empirical endeavour whose frontiers are extended by means of experiment and observation.

It is argued elsewhere on this web site that this reaction to old methods was perhaps an over-reaction as it plays down the significance of language and our intuitive logic.

Classifications may themselves contribute to knowledge generation. This occurred, for example, with the prediction of new and, as yet, undiscovered elements and their properties following the construction of the Periodic Table, and the new classifications and categorization resulting from new scientific technology, as with: carbon dating, DNA analysis, remote sensing, radio-astronomy, the crystalline structure of gems (rather than their hardness) etc.

Language & representation

Language provides us with a symbolic representation of the world. As scientists we are prone to think of the scientific description of the world as ‘reality’ – the way the world actually is. And yet we are constantly testing these beliefs. We refer to well-researched and reliable evidence-based knowledge as a ‘fact’. But we do well to remember that in so doing we are acknowledging that factual statements are statements based on strongly corroborated evidence, to be contrasted with uncritical assertions or opinions or an uncontested assumption about ‘way the world actually is’.

The concepts and categories that make up our language are linked into a web of interconnected knowledge. We need to ensure that the categories we use to organize this knowledge are the best-for-purpose that we can possibly produce. This is the task of science.

So, how are our inner experiences transformed into a language that can convey information from me to you?

We do not think in words, we think in ‘mentalese[9] – but to share our cogitations with others we must translate mentalese into a spoken and written language.

The way we structure language provides us with insight into the process of classification itself as it involves the organization/classification of words.

Web, string, tree

We may think of the way we structure language using a metaphor proposed by cognitive scientist and linguist Steven Pinker who refers to it as ‘the web, the string, and the tree’.

We have in our minds a web of interrelated categories. We organize these ideas into a linear sequence (spoken or written) – a string – according to the rules of syntax which, together with the rules of word formation comprise its grammar. Grammar is our (species-specific) solution to getting complicated thoughts from one head to another. Words are then arranged into phrases that are nested within sentences in the form of an inverted hierarchical tree.

‘Syntax then is an app that uses a tree of phrases to translate a web of thoughts into a string of words.’ The listener then works backwards, fitting them into a tree and recovering the links between the associated concepts.’

So, we structure language like a nested hierarchy that is constructed in a boxes-within-boxes way with sentences containing substructures (phrases) that form an inverted tree if presented pictorially on the page.

Parse Tree as a Nested Hierarchy

Parse Tree as a Nested Hierarchy

S for sentence, the top-level structure in this example
NP – noun phrase. The first (leftmost) NP, a single noun “John”, is the subject of the sentence. The second one is the object of the sentence.
VP – verb phrase, which serves as the predicate
V – verb. In this case, it’s a transitive verb hit.
D – determiner, in this instance the definite article “the”
N – noun

Courtesy Wikimedia Commons – Tjo3ya – Accessed 3 January 2021

Units of classification

Classification proceeds by the grouping of categories – and any category may serve as a unit of classification. This provides a simple definition of ‘category’ as anything that can serve as a unit of mental processing, and therefore of classification. Taxonomy is, in effect, meta-classification: it is the study of classification itself. The specialist term for a unit of a classification is taxon (a contraction of ‘taxonomic group’ with the plural taxa). However, in practice it is usually used to denote kinds of organisms in a biological classification. The word ‘category’ implies the degree of generality appropriate to the discussion here.

Kinds of categories

It is tempting to conclude that, since anything we can think of or imagine becomes a category, then the totality of the categories I can generate becomes the totality of my mental world, and the totality of categories available to humanity becomes the totality of its collective learning.

Be that as it may, an immediate question arises. How are we to classify all these categories? Is it possible to provide an objective classification of all conceivable categories? Or, to express this another way: on what grounds can we select one classification of all the available categories over any another classification?

Suffice it to say that this (metaphysical) question ‘How should we classify everything that there is?’ has been an open question throughout the history of philosophy. The question of ‘what there is’ and the ‘nature of reality’ are metaphysical questions that have baffled the worlds best minds throughout history and may well have no answer. For an extended discussion of this question, I invite you to read the article on reality.

Regardless, there are two important points to be made here:

Purpose, utility, reason

When we examine any grouping of categories that we might make, it becomes apparent that we have formed these groupings for some purpose, use, or reason. Classifications are decision-making tools. There are an infinite number of ways of classifying categories but the kind of classification we choose will depend on the purpose of the classification.

This implies that the way we describe the world, even scientifically, has an element of subjectivity that we are apt to ignore. There is always lurking somewhere the idea that, as scientists, we are either examining the world as it actually is or making advances that are bringing us closer to such a point. Either way, the ‘true nature’ of the world will not depend on human subjective judgement.

A difficulty arises. To operate effectively in the world we must have some view about the way it actually is. Intellectually we doubt that this is knowable.

Intuition

Needing a resolution to an immediate practical problem we fall back on our intuitions about the nature of reality.

One intuition about the ‘true nature’ of the world emulates the way our minds intuitively structure: our language into a metaphorical hierarchy of groups nested within other groups; the world into a hierarchy of levels of organization; organisms into a nested hierarchy of ranks as levels of organization. 

The philosophical problem of category choice for our categorizations-classification dissolves when we realize that those we create, including scientific ones, are decision-making tools.

Thus, classification imposes order by organizing categories into groups to achieve an objective, purpose, or use. And it does this by using selection criteria.
Fortunately, we do not have to pursue this question further here.

Names

The most obvious way in which we communicate about categories is by using names of greater or lesser generality. So there may be, for example, explicit reference to ‘my cup’ and ‘the chair by the window’, although it might also be useful to speak in more general terms about ‘cups’ and ‘chairs’, or in even more general terms about ‘furniture’ and ‘crockery’. In other words names, as representations, relate to the world in complex ways.

If we are seeking clarity in our communication, then we need to feel secure about the categories that we are using. Unfortunately, they express degrees of abstraction and this makes them confusing. I can understand clearly what I mean by the cup of coffee in my hand, but what about the category ‘cup’ itself, or the category ‘crockery’? In what way do they exist or manifest themselves? How reliable, clear, and distinct are they when used as representations in scientific classifications? In a scientific classification how ‘real’ is a species, genus, family, or order? Are any of these categories better representations of things in the world than the others?

Here it is useful to distinguish two extreme kinds of category – classical and fuzzy.

Classical categories

Philosophers have sought clarity in communication by using categories that are both clear and distinct. Plato wanted to establish categories for the external world that ‘carved nature at the joints’, by which he meant dividing the physical world into units that we believe exist in nature rather than in our minds.

Aristotle described what we now call ‘classical’ categories which had defining features (selection criteria) that were both necessary and sufficient. These defining features were then known as ‘essences’, and the use of these classical categories became known as ‘essentialism’. The value of these categories was that they were clearly defined, mutually exclusive, and collectively exhaustive – which did indeed provide a basis for clear and distinct ideas.

One obvious scientific example of classical categories is the periodic table of elements, each element defined by its atomic number. Though gold has many properties, scientists are generally agreed that a definition of gold as the element having the atomic number 79 is both necessary and sufficient. Unfortunately, such clarity is found more in logic and mathematics than in nature.

One feature of the Scientific Revolution was its recognition that the search for essences in nature was a vain hope. For example, the diagnosis of a particular species aspires to being as close as possible to being a classical category, but evolution by descent with modification (rather than special creation) has made the possibility of providing ‘essential’ diagnoses of a species (as a classical categories) a tall order.

Fuzzy categories

Most categories applied to natural objects (and the meanings of most words), are more blurry; they grade into other categories at their boundaries.

As the philosopher Ludwig Wittgenstein pointed out, the notion of a ‘game’ is not a classic category. The many different activities that we call ‘games’ show a ‘family resemblance’ rather than a set of necessary and sufficient (essential) conditions. In other words, what we mean by ‘game’ grades into the meanings of other categories making it a fuzzy, rather than clear and distinct, category.

Awareness of the wide application of fuzzy categories in our communication has given rise to new conceptual clustering tools like those developed in fuzzy mathematics (fuzzy logic and fuzzy set theory which developed in the 1960s) in which objects may belong to one or more groups but to varying degrees. Psychologists studying ‘category learning’ investigate the possible ways our brains compare categories and establish group membership.

For the scientist, the point here is to be aware of the degree of clarity of the categories under investigation along with the ambiguity of metaphor.

Systems of classification

It is now time to look more closely at the actual process of grouping objects.

What are the critical elements of any classification system – how do we go about grouping objects?

We need to know how, in general terms, classification systems are structured, so that we can determine their strengths and weaknesses.

The characteristics of any classification that can be critically examined are: its reason, selection criteria, and structure.

Special & general purpose

Before looking at classification systems in general, a distinction should be made between general- and special-purpose classification.

Most of our mental categorization is of no interest or consequence for other people – the way I arrange my daily activities, create a shopping list, or, more or less unconsciously order my thinking around the content of the book I am reading, and so on. This aspect of our mental classification can be described as ‘general purpose categorization’.

But sometimes the classification of categories becomes an important social activity, examples being scientific classifications, transport timetables, point-of-sale systems, and so on. These formal classifications often require careful deliberation and may engage the latest technology that pushes our collective learning to its limits.

Scientific classifications are, in this sense, special-purpose classifications.

Taxonomy & classification

For the purposes of this article, which discusses taxonomy in a non-discipline-specific sense[10], the objects or units of study are referred to as categories.

Classification is the actual process of ordering or grouping of categories, while taxonomy is then meta-classification, the study of the principles and procedures of classification.

Sometimes we also speak of classification as an object rather than a process, a classification then being a complete category schema of a particular classification system – such as a diagram representing the classification of the plant kingdom.

Purpose or reason

Classifications do not exist in the world, they exist in our minds, and our minds operate intentionally – they are goal-directed.

Consider any grouping of categories that you might make and it will be evident that the grouping has been made for a purpose or reason – to order some property or characteristic, to assess desirability, and so on. This aspect of classification can be called its ‘purpose’ or ‘reason’.

Selection criteria

The best classifications are those that fulfil, in the most efficient way, the reason for their construction. To maximize the efficiency of a classification we refine, as far as possible, the selection criteria that filter the objects being classified. Careful choice of selection criteria reduces the number of possible outcomes and increases the precision of the result.

Categorization gathers complexity with not only the number and kind of objects being classified, but also number and kind of selection criteria. A simple alphabetical list is a classification based on one selection criterion (letter of the alphabet). In contrast, organisms are scientifically classified using selection criteria in such large numbers that a computer is required to build the classification system.

Structure

The structure of classifications – the arrangement of their groups – can take many forms.

We know about the properties of the most common structures encountered through the work of scientists working on the classification or organisms, and librarians working on the organization of their library catalogues.

Hierarchies

Many classification systems exhibit some kind of hierarchy, that is, they rank or prioritize their objects so that related objects are arranged in metaphorical levels, like the rungs of a ladder with a ‘top’ and ‘bottom’. As we have seen, this is the way that language is itself constructed.

Nested hierarchies

In a strict nested hierarchy the groups are contained within other groups like a Russian doll, which contains another doll, which contains another doll, and so on.

A scientific example would be the Linnaean biological classification of organisms into orders, which contain families, which contain genera, which contain species . . . etc. Knowing that a plant has the species name Lactuca sativa (Lettuce), connects us to a vast store of associated historical and biological information. An example of how this kind of plant classification works at high levels would be the single category ‘seed plants’ which is then divided into the groups ‘flower-bearing plants’ and ‘cone-bearing plants’. The flower-bearing plants can then be divided into those which have one seed leaf (monocotyledons) and those which have two seed leaves (dicotyledons) . . . and so on down the hierarchy of ranks.

Strict nested hierarchies like this exhibit several important properties:

Inclusivity – they are progressively more inclusive as ranks go from bottom to top
Exclusivity – an item in a strict hierarchy can only belong to one group at a particular ‘level’ or rank.
Transitivity – the properties that define the objects at higher ranks pass on to the lower ranks
Clear boundaries – the properties defining group membership at a particular rank must be both necessary and sufficient (a classical category)

An example of transitivity would be that all vertebrate animals (Vertebrata) have a vertebral column no matter how they are subsequently subdivided; sub-groups, though resembling one-another by sharing the properties of ‘higher’ groups, nevertheless differ in the properties that uniquely define them.

A name can thus express both similarity and difference. So, Homo sapiens as a species shares the property of being human as expressed in the genus name Homo, but it differs from other species of human by being H. sapiens, the ‘Wise human’. There is thus a clever association and distinction) – the binomial (a name consisting of two words) expresses both similarity and difference at the same time

An example of exclusivity would be that Homo sapiens cannot be, at the same time, Homo heidelbergensis.

Strict nested hierarchies require clarity about similarities and differences between groups. Hierarchical definitions express both affinity and distinction in an economical way.

Transitivity allows the hierarchical structure to build up information that is useful for prediction, while inclusivity (the containment of groups within groups) demonstrates the evolutionary principle of descent with modification.

The formal structure of nested hierarchies works well for items that can be clearly defined, because they have unambiguous group boundaries. However, in daily life we use many categories with indistinct boundaries so the demand for mutual exclusivity cannot be met satisfactorily.[6] In such cases the members of groups at a particular rank sharing family resemblance rather than fulfilling strict necessary and sufficient conditions – and some items at a particular rank may share closer resemblance than others.

In addition, limited knowledge can diminish the power and reliability of definitions and grouping items using more than one criterion can become unwieldy (say classifying plants based on both flower structure and fruit structure).

The effectiveness of a hierarchy in achieving its purpose will only be as good as the knowledge used in its construction and lack of clarity about items and their definition diminishes the power of transitivity.

Difficulties in creating clear categories in science are well known, for example, in the classification of rapidly-changing viruses or in defining the nature of particular smells. Descent with modification can itself lead to graded transitions rather than necessary and sufficient groupings (essentialism) as we try to impose logical order on graded nature.

Modern plant classification (cladistics, phylogenetic and molecular systematics) is based on presumed evolutionary relationships, rather than arbitrary assignments into ranks,; it recognizes species but does not use the terms genus, family, order, class, phylum or kingdom. Thus, cladistics has no ranks – but it does have a hierarchy which arises from the fact that some organisms share a more recent common ancestor with each other than they do with other organisms, a consequence of descent with modification. A taxon that includes an ancestor and all of its descendents is called a clade.

Trees

Another kind of hierarchy is exemplified by military rank. This hierarchy has clear distinctions between groups (like private, sergeant and lieutenant) but there is minimal transitivity between the groups so, for example, the characteristics shared by a private and a sergeant are somewhat obscure.

In sum, trees lack inclusivity: though a species is a member of a genus which is a member of a family – a private is not a subdivision or kind of Sergeant who is, in turn, a kind of Lieutenant. A tree indicates a chain of command but does not include a clear definition of the nature of the authority.

Tree – a nested hierarchy of Army Officers.
Trees lack inclusivity

Courtesy Wikimedia Commons – Totobaggins – Accessed 5 January 2021

Partitive hierarchies

A further kind of hierarchy is the partitive hierarchy. A partitive hierarchy might arise, for example, when we subdivide a geographic region. Melbourne is a part of the state of Victoria, which is a part of Australia. This is an inclusive hierarchy (though Victoria is not a kind of Australia it is a part of it) where certain properties are shared.

Partitive hierarchies share, with nested hierarchies, the characteristic of passing from the general (the most inclusive domain) to progressively smaller or less inclusive parts. But note that a simple confusion can arise here. Objects that share the characteristic of just being part of something can be quite different in general character: an apple core, a train ticket and bottle may all be parts of the waste bin while, in a nested hierarchy of animals we know that those animals that are vertebrates will share certain similarities.

Trees require a knowledge of the characteristics of the items being classified. The structure of the tree will be determined by the nature of the relationship between the parts: part-whole; cause-effect; process-product; start-end etc.

Trees organize categories in a way that defines how they are related and/or the degree to which they are related (spatially, metaphorically), and/or the relative frequency of items within a particular category. However, a tree is constrained by the order in which distinctions are drawn and this may require subsequent modification.

In a hierarchy the information flows (metaphorically) not only ‘upwards’ and ‘downwards’ between levels, but ‘laterally’ between items at the same level.

In trees the ‘lateral’ categories might contain very different objects so they tend to be strong along only one dimension of interest and are not so effective at representing multidirectional complex relationships. As with hierarchies the choice of key defining characteristics can be a matter of dispute and trees allow only partial inference.

Relative merits

The goal of these classifications, like that of all science, is to maximize representational power. It is important to be aware of the strengths and weaknesses of these forms of classification because when we start out on a new project, wishing for clarity in our categories and their relations, a methodology becomes a major asset.

Each method has its own goals, structural properties, strengths, and weaknesses.

Scientific classification

Knowledge grows cumulatively and to make an impact in any field of study a student must add to the fine detail of their particular discipline by refining existing categories and adding new ones. As students we can become enmeshed in our own particular region of the knowledge web. Proceeding by analysis and the desire to understand the fine detail we do indeed ‘learn more and more about less and less’.

Drilling ever deeper by analysis within a narrow topic it can become increasingly difficult to establish a synoptic view of the intellectual landscape – something we desperately need to reassure ourselves that effort and resources are being directed towards the areas of greatest need.

Foundations of taxonomy

This lengthy introduction to classification has involved many complex ideas. Before moving on to the specific case of plant classification it is now possible to draw up some conclusions about taxonomy in general as it relates to the topics discussed on this web site.

Classification has its origins in the pre-conscious structuring of the objects of our experience (categories) that we intuitively arrange toward some end or purpose that helps us to cope with our daily lives, survive, and flourish.

To build a classification requires that the objects to be classified are subjected to a filtering process using selection criteria. This is the way that we intuitively relate to the world – the way that we innately order the world before conscious deliberation begins. Four interrelated aspects of this innate mental processing can be usefully distinguished: segregation, focus, classification, and ranking. This determines much of our human umwelt[1], our sense of reality.

However, not all classification is innate and intuitive – it can occur with varying degrees of conscious deliberation, or with some aspects being conscious and others unconscious. At one extreme might be the way our eyes move intuitively towards the source of a noise. Much more complex would be the combination of conscious and intuitive prioritizing of the objects around me when I am driving. The solving of a mathematical problem seems a fully conscious process. When classification is fully conscious it becomes part of the process we refer to as ‘reason‘.

For now, it is evident that plants can be classified in an infinite number of ways using an infinite number of selection criteria. The question then arises as to why we regard the scientific classification of plants with such respect. What is so special about the scientific classification of plants and does it warrant the attention and resources that it currently receives? This preliminary examination of taxonomy in general provides a perspective from which to view the current status of plant taxonomy.

This discussion of plant classification has given us some insight into the way our minds work and how this has a bearing on both the progress of science and the way we make decisions. Some classifications are progressive because they can be refined (improved) over time and then handed on to future generations.

Scientific classifications, in particular, are progressive. They have told us much about the physical world. But to address modern problems, such as that of sustainability, our knowledge of taxonomy can be taken in a new direction.

This web site, in examining the history of the relationship between humans and plants, has shown how the economic importance of plants from the dawn of humanity into the 19th century imbued the biological classification of plant kinds with a special significance. From the 16th to 19th centuries, Europeal colonial expansion combined with science and the technology of Indistria to amass what was , in effect, an inventory of the world’s vegetal resources. Now, in Informatia, the task of plant description and classification is nearing completion. Though there will always be a place for plant taxonomy it is now time to direct our taxonomically developed collective learning more towards the relationship, not between plants and other plants, but between plants and humans and, more specifically, the link between plants, humans, and the environment.

There are now many text books examining the classification of plants incorporating the latest and most sophisticated computational and gene technologies. The next article examines plant classification, not in a narrow biological sense, but in relation to the future of humanity.

Key points

  • Our minds are constantly – both consciously and unconsciously – selecting, ordering, and arranging the objects of our experience
  • The foundations of classification are laid with the pre-conscious structuring of experience that occurs before conscious deliberation
  • Our intuitive ordering of the world is part of the way we represent the world, and it is the source of some of our metaphysical intuitions about the world. It is therefore part of our human nature and human reality, our uniquely human collective mental umwelt.
  • Included in the pre-conscious mental processing there is: segregation, focus, categorization, and ranking. These aspects of our mental processing are hard-wired into our biological make-up; without them we could not survive
  • For simplicity we can call all communicable units of experience categories, and it is these categories that can be variously grouped and prioritized according to selection criteria.
  • The grouping of units of our experience towards some end or goal may be called categorization, and when categorization becomes a serious conscious and deliberate endeavour, as it does in science, we call it ‘classification’.
  • Classification is the ordering or grouping of objects by criteria selected to achieve an end or goal.
  • Taxonomy is the study of classification, its principles, and procedures.
  • We communicate with one-another using language which provides us with a symbolic representation of the world. The categories that make up our language are linked into a web of interconnected knowledge.
    • One of the tasks of science is to ensure that the categories we use to describe and organize our collective learning are the best possible. This is a task for science.
    • Classifications are decision-making tools. There are an infinite number of ways of classifying categories but the categories chosen will depend on the purpose of the classification.
    • Biological classification of organisms arranges them by their presumed evolutionary relationships
    • One method of scientific advancement is the designation of an are of study (an academic discipline) with a community of scientists that constantly refine the categories, principles and procedures used by that study
    • Plant classification is the arrangement of plants into groups according to selection criteria that serve a particular purpose. However, in common usage, the expression ‘plant classification’ refers to the organization of plants into groups that reflect their evolutionary relationships as plant taxa which, prior to Darwin and the theory of evolution, involved the organization of mostly morphological characters as similarities and differences.
    • We study plants through the broad range of scientific disciplines that fall under the heading of plant science (formerly the narrower discipline of botany). There is no current and widely accepted system of categories, principles and procedures for the study of the topic ‘plants and people’
    • ‘Categorization’ is a general-purpose term. When categorization becomes a more serious and shared social activity we call it ‘classification’
    • Classification is the ordering or grouping of objects by criteria that satisfy an end or goal.
    • Taxonomy is the study of classification, its principles, and procedures.
    • Classification begins with the pre-conscious structuring of experience that occurs before conscious deliberation. This intuitive ordering of the world is part of the way we represent the world, and it is the source of some of our metaphysical intuitions about the world. It is therefore part of our human nature and human reality, our uniquely human collective mental umwelt.
    • Included in the pre-conscious mental processing that is part of our human nature are: segregation, focus, classification, and ranking. These aspects of our mental processing are hard-wired into our biological make-up; without them we could not survive
    • For simplicity we can call all communicable units of experience categories, and it is these categories that can be variously grouped and prioritized according to selection criteria.
    • We communicate with one-another using language. Language provides us with a symbolic representation of the world. The categories that make up our language are linked into a web of interconnected knowledge. We need to ensure that the categories we use to organize this knowledge are the best possible. This is a task for science.
    • Classifications are decision-making tools. There are an infinite number of ways of classifying categories but the categories chosen will depend on the purpose of the classification.
    • Biological classification of organisms arranges them by their presumed evolutionary relationships
    • One method of scientific advancement is the designation of an are of study (an academic discipline) with a community of scientists that constantly refine the categories, principles and procedures used by that study
    • Plant classification is the arrangement of plants into groups according to selection criteria that serve a particular purpose. However, in common usage, the expression ‘plant classification’ refers to the organization of plants into groups that reflect their evolutionary relationships as plant taxa which, prior to Darwin and the theory of evolution, involved the organization of mostly morphological characters as similarities and differences.
    • We study plants through the broad range of scientific disciplines that fall under the heading of plant science (formerly the narrower discipline of botany). There is no current and widely accepted system of categories, principles and procedures for the study of the topic ‘plants and people’

Glossary

 

category – any unit of experience that can be used for categorization
categorization – the organization of categories
classification – the arrangement of objects into groups by criteria that depend on the purpose of the classification
focus – the restriction of our attention to a limited range of representational units so that, at any given time, our attention is divided into a foreground and background
purpose (taxonomy) – the reason for, or goal, of a classification
nested hierarchy – the taxa and their groupings are contained within other groups in a boxes-within-boxes fashion, like a Russian doll
rank-value – the ranking (valuing or prioritizing) of objects relative to one-another within a classification system.
segregation – the organization of experience into meaningful representational units, both those of cognition (concepts), and those of perception (percepts)
taxonomy – is the study of the principles and procedures of classification

**—

First published on the internet – 1 March 2019

… revised 11 January 2021

 

Scientific classification.

A flowering plant phylogeny of 2020
including the then recognized 435 plant families

The colours of the branches and the outer circles represent the major angiosperm clades (branches of the plant evolutionary tree) as indicated in the caption (ANA, Amborellales + Nymphaeales + Austrobaileyales). The illustrations around the circumference show 32 plant families and their position in the tree.

The flowering plants (angiosperms) arose in the Early Cretaceous about 145–100 million years ago, supplanting the earlier ferns and conifers (pteridosperms and gymnosperms). Palaeobotanical evidence indicates that this replacement was gradual, flowering plants not becoming dominant until the Palaeocene about 66–56 million years ago. The timing, geographic sequence, and plant composition of this diversification remains uncertain. There appear to have been substantial time lags, mostly around 37–56 million years, between the origin of families (stem age) and the diversification leading to extant species (crown ages) across the entire angiosperm tree of life. Families with the shortest lags occur mostly in temperate and arid biomes compared with tropical biomes. The ecological expansion of existing flowering plants, it seems, occurred long after their phylogenetic diversity originated during the Cretaceous Terrestrial Revolution.

Courtesy public domain license. Adapted from the originals provided by S.M., the Peter H. Raven Library/Missouri Botanical Garden and the Mertz Library/New York Botanical Garden

Flowering Plant Phylogeny diagram
Print Friendly, PDF & Email