Thomistic Philosophy
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Thomistic Metaphysics
Act and Potency

POTENCY : (a.k.a. POTENTIALITY) THE CAPACITY OR APTITUDE FOR SOMETHING   Click to Expand ⤵

  1. Objective Potency (a.k.a. Pure Possibility or Logical Possibility)
    The capacity of a nonexistent being for existence   ⤵
    1. Absolute Possibility (a.k.a. Intrinsic Possibility or Internal Possibility or Negative Possibility)
      The capacity considered absolutely in itself
      (e.g. the existence of a chair is intrinsically possible, whereas the existence of a square circle is intrinsically impossible)
    2. Relative Possibility (a.k.a. Extrinsic Possibility or External Possibility or Positive Possibility)
      The capacity considered relative to another being's power to produce it   ⤵
      1. Natural Possibility (a.k.a. Physical Possibility)
        The capacity considered relative to another being's natural power to produce it
        (e.g. the existence of Shakespeare's Works being produced by a human is naturally possible, whereas the existence of Shakespeare's Works being produced by the color blue is naturally impossible)
      2. Moral Possibility
        An ethically permissable possibility which can be produced by a rational agent
        Note: Some might specifically call this "morally good" or "morally advisable" possibility since the term "moral possibility" can be used to include any act done by a rational agent regardless of whether it is good or evil
        (e.g. eating healthy is often a morally good possibility, whereas murdering an innocent person is not)
      3. Plausible Possibility (a.k.a. Plausibility)
        A possibility which does not involve serious difficultly for another being's power to produce it
        (e.g. for a typical person, swimming across a small pond is possible without serious difficulty, whereas swimming across the Atlantic Ocean is not)

  2. Subjective Potency (a.k.a. Physical Potency or Real Potency)
    The capacity of something already existing for another act or perfection
    Note: This is considered "Potency" in the more proper sense of the term   ⤵
    1. Active Potency (a.k.a. Operative Potency or Power)
      The capacity to do or make something
      Note: This is also technically considered a kind of actuality (specifically, First Actuality) relative to the thing that possesses it, but it also a kind of potency relative to what it can do
      (e.g. a horse has the active potency for galloping)
    2. Passive Potency (a.k.a. Receptive Potency or Potentiality)
      The capacity for receiving something, to be acted on, to be modified, etc.
      Note: While "Potentiality" is sometimes used synonymously with "Potency," it usually refers to Passive Potency more specifically
      (e.g. a horse has the passive potency for being whipped)
ACT : (a.k.a. ACTUALITY) ANY ENTITY WHICH PERFECTS A THING IN ITS BEING   Click to Expand ⤵

  1. Mixed Act (a.k.a. Mixed Actuality)
    Act which is mixed with potentiality
    (e.g. all created things, that is, everything that is not God)   ⤵
    1. Entitative Act
      What a thing is (statically speaking)   ⤵
      1. Essential Act (a.k.a. Act of Essence or Actuality of Essence or Formal Act)
        That which makes a being what it is   ⤵
        1. First Act [as pertaining to Being] (a.k.a. First Formal Act or Substantial Form)
          That which makes a being what it is in itself (or by itself)
        2. Second Act [as pertaining to Being] (a.k.a. Second Formal Form or Accidental Form)
          That which makes a being what it is in another

      2. Existential Act (a.k.a. Act of Existence or Existential Act or Entitative Act)
        That which makes a being exist

    2. Operative Act
      What a thing is in terms of its operations/activities   ⤵
      1. First Act [as pertaining to Operation] (a.k.a. Power)
        When a thing actually possesses the ability to do something
      2. Second Act [as pertaining to Operation] (a.k.a. Operation [of a Power])
        The using of a power

  2. Pure Act (a.k.a. Pure Actuality)
    Act which is unmixed with any potentiality
    (the only example of this is God)   ⤵