Thomistic Philosophy
Click on any item in the outline that has an arrow icon ( ⤵ ) to reveal more information about it:

Thomistic Metaphysics
Substance and Accident

SUBSTANCE : THAT WHICH EXISTS BY ITSELF (or "in itself")
Note: This is often considered the first "Category of Being"
(e.g. rock, flower, dog, human, angel, God)   Click to Expand ⤵
  1. Simple Substance
    A substance without parts
    (e.g. God)
  2. Composite Substance (a.k.a. Compound Substance)
    A substance with parts
    (e.g. a human person is a composite substance, whose "parts" can include his head, eyes, hands, legs, stomach, kidneys, etc.)   ⤵
    1. Incomplete Substance (a.k.a. Substantial Constituent or Substantial Part or simply: Part)
      A constitutive element of a material substance
      (e.g. leg, head, arm, eye, stem, heart, soul)
    2. Complete Substance (a.k.a. Substantial Whole or Hypostasis or Suppositum or Supposit)
      An individual, whole substance existing entirely by itself
      Note: The independent existence that complete substances have is called "subsistence" (that is, they "subsist"), unlike the more dependent existences of "parts" and "accidents"
      (e.g. rock, flower, dog, human)   ⤵
      1. Spirit
        An incorporeal substance (i.e. a substance that is non-physical a.k.a. immaterial)
        Note: A "soul" is not considered a "spirit" in this sense because it is an incomplete substance in itself, requiring a body to compose a complete substance
        (e.g. angel)
      2. Body
        A corporeal substance (i.e. a substance that is physical a.k.a. material)
        Note: The term "body" might be used in various other ways (so as to include incomplete corporeal substances, for example)   ⤵
        1. Mineral
          An inorganic body (i.e. a corporeal substance that is non-living a.k.a. inanimate)
          Note: The term "mineral" has a more narrow use in modern science
          (e.g. iron)
        2. Organism
          An organic body (i.e. a corporeal substance that is living a.k.a. animate)
          Note: The form of an organic body is traditionally referred to as a "soul" (whether it be an immortal soul or an immortal soul or not)   ⤵
          1. Plant
            A non-sentient organism (i.e. a corporeal, organic substance that does not have senses)
            Note: This more traditional use of the term "plant" would also encompass "fungi" (and arguably "bacteria" as well), contrary to how modern science would now uses the term
            (e.g. grass, flower, tree)
          2. Animal
            A sentient organism (i.e. a corporeal, organic substance that does have senses)
            Note: Contrary to some popular usage, "sentient" does not mean "highly intelligent" but rather merely posseesing senses, which, depending on the animal, can include seeing, hearing, smelling, tasting, touching or perhaps others as well (also, alternate words to the term "sentient" can include: sensory, sensible, sensitive, sensual, sensate, etc.)   ⤵
            1. Beast (or simply: Animal)
              A non-rational animal (i.e. a corporeal, organic, sentient substance that does not have reason)
              (e.g. horse)
            2. Human
              A rational animal (i.e. a corporeal, organic, sentient substance that does have reason)
              Note: Possible extraterrestrial life forms that are also corporeal and rational would also be called "human" in this sense (also, another word for "rational" is "intellectual" though some philosophers distinguish these two terms)
              (e.g. Socrates)

ACCIDENT : (a.k.a. ATTRIBUTE or PROPERTY) THAT WHICH EXISTS IN ANOTHER (that is, in a substance or in another accident)
Note: This is often considered to include the last nine "Categories of Being" (for further subdivisions of accidents, see the 10 Categories of Being page)
(e.g. size, color, texture, friendship, running)   Click to Expand ⤵

  1. Two Kinds of Accidents — distinguished by Essentiality   ⤵
    1. Proper Accident (a.k.a. Essential Attribute or Essential Property or simply: Property)
      An accident which necessarily "flows" from the essence of a substance (and thus exclusively belongs to that kind of substance)
      (e.g. being unmarried is an essential attribute of being a bachelor)
    2. Common Accident (a.k.a. Inessential Attribute or Accidental Property or simply: Accident)
      An accident which does not necessarily flow from the essence of a substance (and thus does not necessarily need to exist in that kind of substance)
      (e.g. having brown hair is an inessential attribute of being a bachelor)

  2. Two Kinds of Accidents — distinguished by Inherence   ⤵
    1. Intrinsic Accident
      An inner modification of a substance
      (e.g. extension, shape, color, capacities)   ⤵
      1. Absolute Accident
        An inner modification of a substance that does not depend upon it being connected to something else   ⤵
        1. Quantity
          An accident which gives material extension to a substance (thus giving it distinct integral parts)
          Note: This is often considered the second "Category of Being"
          (e.g. length, weight, mass, density)
        2. Quality (a.k.a. Qualification)
          An accident modifying and/or completing a substance in its being or operation
          Note: This is often considered the third "Category of Being"
          (e.g. color, sound, shape, texture, habits)

      2. Relative Accident (a.k.a. Real Relation or simply: Relation)
        An inner modification of a substance that does depend upon it being connected to something else
        Note: This is often considered the fourth "Category of Being"
        (e.g. friendship, parenthood, kinship)

    2. Extrinsic Accident
      An accident which is outside the subject (but is still said to modify it in some way)   ⤵
      1. Partially Extrinsic Accident
        An accident which is defined by having one of its parts (namely, its beginning or its end) being inside the subject and the other possibly being outside it   ⤵
        1. Action
          An accident whose beginning is in the subject but whose end can be outside of it (viz. a partially extrinsic accident with regard to its principle)
          Note: This is often considered the fifth "Category of Being"
          (e.g. hitting)
        2. Passion (a.k.a. Reaction)
          An accident whose beginning can be outside the subject but whose end is in the subject (viz. a partially extrinsic accident with regard to its term)
          Note: This is often considered the sixth "Category of Being"
          (e.g. getting hit)

      2. Totally Extrinsic Accident
        An accident which is defined by being wholly outside the subject   ⤵
        1. Position
          A totally extrinsic accident as a measure   ⤵
          1. Position in Time (a.k.a. Temporarlity or "When" or simply: Time)
            A position with regard to "before" and "after" (i.e. the measure of change)
            Note: This is often considered the seventh "Category of Being"
            (e.g. today, tomorrow, soon, in the beginning, last year, now, in five minutes)
          2. Position in Space (a.k.a. Spatial Position)
            A position with regard to "where" (i.e. the measure of things with respect to other things at a given time)   ⤵
            1. Place (a.k.a. Location or Position or "Where")
              An accident which determines the subject as to its position with reference to other things
              Note: This is often considered the eighth "Category of Being"
              (e.g. upstairs, on the table, at home)
            2. Posture (a.k.a. Orientation or Position or Situation)
              An accident which determines its subject with reference to the arrangement/disposition of its own parts
              Note: This is often considered the ninth "Category of Being"
              (e.g. leaning, prone, bent, curled, straightened)

        2. Habiliment
          A totally extrinsic accident not as a measure; an accident by which a bodily substance is externally modified (furnished) with another
          Note: This is often considered the tenth "Category of Being"
          (e.g. clothed, hatted, armed)