Questions from a previous discussion about the "Species Problem" are as follows:
How would you answer the following questions?
1) Does the term "species" refer to either individuals or classes?
2) Is "species" real or or not? In other words, does "species" have an objective existence outside our intellectual abstractions or is it just a useful delusion?
3) How do you define species so that it adequately catalogue all the different life-forms?
A Scholastic approach is as follows:
The thesis whereby "species" is a natural kind and individuated by essences is known as essentialism. Natural kinds are universals not individuals on this view.
The Predicables
The Scholastic approach (and others) differentiates between the five predicables; Species, Genus, Differentia, Property and Accident (Coffey P, The Science of Logic). The predicables are relations to individual things or subjects or substances.
The "species" predicable is related to an individual substance in a manner that describes whole specific nature of the individuals in a class.
The "genus" predicable is related to an individual substance in a manner that describes something about the substance that is in common with other substances.
The "differentia" predicable is related to an individual substance in a manner that describes something about substance that distinguishes it from other substances in the same genus.
The "propria" (or property) predicable is related to an individual substance in a manner that describes something about the substance that necessarily follows from its essence or nature.
The "accidens" predicable (or accident) is related to an individual substance in a manner that describes an attribute about the substance that does not necessarily follow from its essence or nature.
The "definition" of a substance is something that describes the nature of the thing that is not only clear but distinct. The "definition" of a substance is described by the "species" predicable and not necessarily the "infima species" but instead the "essential species" or "natural species". The genus above the "essential species" is called the "proximate genus".
The "accidens" predicable is divided between separable and inseparable accidents. An inseparable accident is "some quality which is found to belong invariably as a matter of fact to all the members of a class" (Coffey P, The Science of Logic Vol1 , p87). A separable accident is a quality that is not necessarily present in all the members of a class.
The Porphyrian tree
One way of demonstrating the relationships between the predicables is by drawing up a Porphyrian tree (Figure 1).
Figure 1: An example of a Porphyrian Tree
Let's take the example of a scalene triangle and apply the various predicables to it (Figure 2).
Figure 2: A Porphyrian Tree for a Scalene Triangle
Therefore:
Summum genus = Mathematical figure
Proximate genus = Straight lined 2D Mathematical figure
propria = Three sides
Essential species = Triangle (Nature or essence = triangularity)
Defiinition = Three sided, straight lined 2D Mathematical figure
Differentia accidens inseparable = all sides are different.
Infima species = Scalene triangle
The answers to the above questions (first two) from a Scholastic view are thus as follows:
1) Species (both essential and infima) refer to a group or population of individuals. I.e it is a class.
2) Essential species are natural kinds and thus a universal. Moderate realism is applied to universals as described here.
The question now is how to apply the concepts to properly catalogue all the different life-forms in reality. The Scholastic differentiation between contingent and necessary being is useful as well as the the differentiation between substance and accident (Figure 3).
Figure 3: Being - Necessary and Contingent
Substance and accident are the summum genus for modes of contingent being. A Porphyrian tree for accidents is described here. Generating a Porphyrian tree to describe the various predicables of substances is thus the next step.
How would you answer the following questions?
1) Does the term "species" refer to either individuals or classes?
2) Is "species" real or or not? In other words, does "species" have an objective existence outside our intellectual abstractions or is it just a useful delusion?
3) How do you define species so that it adequately catalogue all the different life-forms?
A Scholastic approach is as follows:
The thesis whereby "species" is a natural kind and individuated by essences is known as essentialism. Natural kinds are universals not individuals on this view.
The Predicables
The Scholastic approach (and others) differentiates between the five predicables; Species, Genus, Differentia, Property and Accident (Coffey P, The Science of Logic). The predicables are relations to individual things or subjects or substances.
The "species" predicable is related to an individual substance in a manner that describes whole specific nature of the individuals in a class.
The "genus" predicable is related to an individual substance in a manner that describes something about the substance that is in common with other substances.
The "differentia" predicable is related to an individual substance in a manner that describes something about substance that distinguishes it from other substances in the same genus.
The "propria" (or property) predicable is related to an individual substance in a manner that describes something about the substance that necessarily follows from its essence or nature.
The "accidens" predicable (or accident) is related to an individual substance in a manner that describes an attribute about the substance that does not necessarily follow from its essence or nature.
The "definition" of a substance is something that describes the nature of the thing that is not only clear but distinct. The "definition" of a substance is described by the "species" predicable and not necessarily the "infima species" but instead the "essential species" or "natural species". The genus above the "essential species" is called the "proximate genus".
The "accidens" predicable is divided between separable and inseparable accidents. An inseparable accident is "some quality which is found to belong invariably as a matter of fact to all the members of a class" (Coffey P, The Science of Logic Vol1 , p87). A separable accident is a quality that is not necessarily present in all the members of a class.
The Porphyrian tree
One way of demonstrating the relationships between the predicables is by drawing up a Porphyrian tree (Figure 1).
Figure 1: An example of a Porphyrian Tree
Let's take the example of a scalene triangle and apply the various predicables to it (Figure 2).
Figure 2: A Porphyrian Tree for a Scalene Triangle
Therefore:
Summum genus = Mathematical figure
Proximate genus = Straight lined 2D Mathematical figure
propria = Three sides
Essential species = Triangle (Nature or essence = triangularity)
Defiinition = Three sided, straight lined 2D Mathematical figure
Differentia accidens inseparable = all sides are different.
Infima species = Scalene triangle
The answers to the above questions (first two) from a Scholastic view are thus as follows:
1) Species (both essential and infima) refer to a group or population of individuals. I.e it is a class.
2) Essential species are natural kinds and thus a universal. Moderate realism is applied to universals as described here.
The question now is how to apply the concepts to properly catalogue all the different life-forms in reality. The Scholastic differentiation between contingent and necessary being is useful as well as the the differentiation between substance and accident (Figure 3).
Figure 3: Being - Necessary and Contingent
Substance and accident are the summum genus for modes of contingent being. A Porphyrian tree for accidents is described here. Generating a Porphyrian tree to describe the various predicables of substances is thus the next step.