Thomistic Philosophy
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Thomistic Metaphysics
10 Categories of Being


  1. Substance
    That which exists in/by itself (the other nine categories are accidents)
    Note: See the Substance and Accident page for subdivisions of substance
  2. Quantity (a.k.a. Quantification)
    An accident which gives material extension to a substance (thus giving it distinct integral parts)   ⤵
    1. Continuous Quantity (a.k.a. Extension)
      A quantity whose parts are connected
      (e.g. time, motion, length, breadth, depth)
    2. Discrete Quantity (a.k.a. Number)
      A quantity who parts are not connected
      (e.g. number, speech)

  3. Quality (a.k.a. Qualification)
    An accident modifying and/or completing a substance in its being or operation   ⤵
    1. Faculty (a.k.a. Natural Capacity or Power)
      A quality that proximately produces an operation (the accidental principle of action)
      Note: "Incapacity" refers to an existing faculty in a weakened state, rather than the total abscence of a capacity   ⤵
      1. Inorganic Faculty
        A faculty that a non-living, material substance can have (though living, material substances may possess them as well)
        (e.g. gravitational attraction, flexibility, adhesiveness)
      2. Vegetative Faculty
        A faculty that a plant (or other living being without senses) can have (though living beings with senses may possess them as well)
        (e.g. nutrition, growth, and reproduction)
      3. Sentient Faculty
        A faculty that an animal can have (though rational, material beings may possess them as well)
        (e.g. sense perception, sense desires, locomotion)
      4. Rational Faculty
        A faculty that a rational being can possess
        (e.g. intellect and will)

    2. Facility
      A modification which perfects a power of operation or a faculty (it does not give the power of operating but rather facilitates or impedes the operation)   ⤵
      1. Habit
        A relatively permanent or stable quality disposing a thing well or ill in its being (entitative) or its operations (operative)
        (e.g. one can have a habit of cleaning up their room, which means their power to clean their room is perfected to some degree and, consequently, made easier)
      2. Disposition
        A relatively transient or unstable quality disposing a thing well or ill in its being (entitative) or its operations (operative)
        (e.g. one might not have a habit of cleaning their room but nonetheless may be disposed to clean it one day, which means it is easy to do in that instance but probably not in most instances)

    3. Affectivity
      Qualities that produce (or result from) some accidental sensible change (regarding either sense perception or sense desire)
      (e.g. color, sound, odor, flavor, temperature, smoothness, roughness, as well as the emotions).   ⤵
      1. Affective Quality (a.k.a. Passible Quality)
        A relatively permanenent quality that produces (or results from) some accidental sensible change
        (e.g. the racial color of one's skin)
      2. Affection (a.k.a. Passible Quality)
        A relatively transient quality that produces (or results from) some accidental sensible change
        (e.g. the momementary blushing color of one's cheeks caused by embarrasment)

    4. Figure (a.k.a. Shape or [in a limited use of the term] "Form")
      A quality resulting from the arrangement of a thing's physical parts (thus a quality resulting from quantity)   ⤵
      1. Natural Form
        A physical shape of something that is there by nature
        (e.g. atomic structure, the structure of a tree)
      2. Artificial Form
        A physical shape of something that is there because of deliberate human action
        (e.g. buildings, machines, works of art)

  4. Relation (a.k.a. Relative Accident)
    A real reference or comparison of one real thing with another
    Note: This is, more precisely, Real Accidental Relation, which is distinct from both Purely Mental Relation and Essential Relation   ⤵
    1. Three Things Necessary to Constitute a Relation   ⤵
      1. Subject
        A being that is referred to another
        (e.g. mother is the subject of motherhood)
      2. Term
        A being to which the being is referred
        (e.g. son or daughter is the term of motherhood)
      3. Foundation (a.k.a. Basis)
        Something in the subject (or in both subject and term) on account of which the subject is referred to the term
        (e.g. the subject having given birth to the term is the foundation of motherhood)

    2. Properties a Relation can have   ⤵
      1. Transitivity
      2. Symmetry
      3. Mutuality
      4. Reflexivity
      5. [more to come]

  5. Action
    The change/influence which proceeds from an agent (the excercise of efficient causality)
    (e.g. hitting something with a baseball bat)   ⤵
    1. Three Things Necessary to Constitute an Action   ⤵
      1. Agent (a.k.a. Efficient Cause)
        The thing that produces the change
        (e.g. a baseball player hitting a baseball)
      2. Patient (a.k.a. Reagent)
        The thing that is changed
        (e.g. a ball getting hit by a baseball player)
      3. Effect
        The change itself that is given to the patient by the agent
        (e.g. the new movement/direction of the ball due to getting hit by the baseball player)

    2. Two Kinds of Actions   ⤵
      1. Transient Action (a.k.a. Transitive Action)
        An action that produces something outside the agent   ⤵
        1. Natural Action
          An action that is the work of nature
          (e.g. snowing, photosynthesis, smelling)
        2. Artificial Action
          An action that is the result of art
          (e.g. cooking, sculpting, engineering)

      2. Immanent Action
        An action that produces an effect which remains wholly within the agent, i.e. either pertaining to the agent's knowledge (cognition) or desire (appetite)   ⤵
        1. Two Kinds of Cognitive Action   ⤵
          1. Sense Cognition
            Apprehension by the senses
          2. Intellective Cognition
            Apprehension by the intellect

        2. Two Kinds of Appetitive Action   ⤵
          1. Sense Appetition (a.k.a. Sensual Desire or [in a limited use of the term] Passion or [arguably] Emotion)
            Inclination to fulfill sensual nature
          2. Intellective Appetition (a.k.a. Intellectual Desire or Volition or Will)
            Inclination to fulfill rational nature

  6. Passion (a.k.a. Reaction)
    The receiving of an action
    (e.g. getting hit by a baseball bat)
  7. Time (a.k.a. Temporarlity or "When")
    A thing's position in time (a measure of duration)
    (e.g. today, tomorrow, soon, in the beginning, last year, now, in five minutes)
  8. Place (a.k.a. Location or Position or "Where")
    A thing's position in space
    (e.g. upstairs, on the table, at home)
  9. Posture (a.k.a. Orientation or Position or Situation)
    The arrangement of the parts of a thing relative to each other
    (e.g. leaning, prone, bent, curled, straightened)
  10. Habiliment (a.k.a. Habit or Habitus or Having or Possession or Condition or State or External Condition)
    An accident by which a bodily substance is externally modified (furnished) with another
    (e.g. clothed, hatted, armed)