Ideas of Thomas Aquinas, by Theme

[Italian, 1225 - 1274, Born Roccasecca, Italy. Dominican monk. Taught by Albertus Magnus. Based Paris, then Italy. Died at Fossanova. 'Doctor Angelicus'.]

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1. Philosophy / A. Wisdom / 2. Wise People
22115 Wise people should contemplate and discuss the truth, and fight against falsehood
1. Philosophy / D. Nature of Philosophy / 5. Aims of Philosophy / a. Philosophy as worldly
22101 Philosophy aims to know the truth about the way things are
2. Reason / A. Nature of Reason / 1. On Reason
1848 We are coerced into assent to a truth by reason's violence
2. Reason / A. Nature of Reason / 4. Aims of Reason
1858 The mind is compelled by necessary truths, but not by contingent truths
2. Reason / B. Laws of Thought / 6. Ockham's Razor
21267 Supposing many principles is superfluous if a few will do it
2. Reason / C. Styles of Reason / 1. Dialectic
22102 Arguing with opponents uncovers truths, and restrains falsehoods
2. Reason / D. Definition / 5. Genus and Differentia
13070 If definitions must be general, and general terms can't individuate, then Socrates can't be defined [Cover/O'Leary-Hawthorne]
11197 The definitions expressing identity are used to sort things
3. Truth / A. Truth Problems / 1. Truth
23176 Truth is universal, but knowledge of it is not
20621 Types of lying: Speak lies, intend lies, intend deception, aim at deceptive goal? [Tuckness/Wolf]
3. Truth / A. Truth Problems / 3. Value of Truth
1852 For the mind Good is one truth among many, and Truth is one good among many
3. Truth / A. Truth Problems / 9. Rejecting Truth
21248 If the existence of truth is denied, the 'Truth does not exist' must be true!
3. Truth / C. Correspondence Truth / 1. Correspondence Truth
22104 Truth is the conformity of being to intellect
5. Theory of Logic / B. Logical Consequence / 1. Logical Consequence
23173 If a syllogism admits one absurdity, others must follow
7. Existence / A. Nature of Existence / 3. Being / e. Being and nothing
11195 If affirmative propositions express being, we affirm about what is absent
7. Existence / A. Nature of Existence / 3. Being / f. Primary being
22103 Being is basic to thought, and all other concepts are additions to being
7. Existence / A. Nature of Existence / 3. Being / g. Particular being
15812 Being implies distinctness, which implies division, unity, and multitude
7. Existence / D. Theories of Reality / 5. Naturalism
21268 Non-human things are explicable naturally, and voluntary things by the will, so God is not needed
7. Existence / E. Categories / 4. Category Realism
16655 Different genera are delimited by modes of predication, which rest on modes of being
8. Modes of Existence / B. Properties / 8. Properties as Modes
16641 Whiteness does not exist, but by it something can exist-as-white
11201 Properties have an incomplete essence, with definitions referring to their subject
8. Modes of Existence / D. Universals / 6. Platonic Forms / d. Forms critiques
11205 If the form of 'human' contains 'many', Socrates isn't human; if it contains 'one', Socrates is Plato
9. Objects / A. Existence of Objects / 5. Individuation / a. Individuation
13090 The principle of diversity for corporeal substances is their matter [Cover/O'Leary-Hawthorne]
9. Objects / B. Unity of Objects / 1. Unifying an Object / b. Unifying aggregates
17555 'One' can mean undivided and not a multitude, or it can add measurement, giving number
9. Objects / C. Structure of Objects / 2. Hylomorphism / d. Form as unifier
16765 Humans only have a single substantial form, which contains the others and acts for them
16766 One thing needs a single thing to unite it; if there were two forms, something must unite them
9. Objects / D. Essence of Objects / 1. Essences of Objects
11202 It is by having essence that things exist
9. Objects / D. Essence of Objects / 2. Types of Essence
11203 Specific individual essence is defined by material, and generic essence is defined by form
9. Objects / D. Essence of Objects / 4. Essence as Definition
11200 The definition of a physical object must include the material as well as the form
9. Objects / D. Essence of Objects / 5. Essence as Kind
11196 Essence is something in common between the natures which sort things into categories
9. Objects / D. Essence of Objects / 6. Essence as Unifier
11208 A simple substance is its own essence
11. Knowledge Aims / A. Knowledge / 2. Understanding
22170 Senses grasp external properties, but the understanding grasps the essential natures of things
11. Knowledge Aims / B. Certain Knowledge / 1. Certainty
23175 The conclusions of speculative reason about necessities are certain
11. Knowledge Aims / C. Knowing Reality / 1. Perceptual Realism / b. Direct realism
21337 A knowing being possesses a further reality, the 'presence' of the thing known
12. Knowledge Sources / A. A Priori Knowledge / 2. Self-Evidence
21249 Some things are self-evident to us; others are only self-evident in themselves
12. Knowledge Sources / A. A Priori Knowledge / 3. Innate Knowledge / a. Innate knowledge
22169 Initial universal truths are present within us as potential, to be drawn out by reason
12. Knowledge Sources / A. A Priori Knowledge / 8. A Priori as Analytic
21250 A proposition is self-evident if the predicate is included in the essence of the subject
12. Knowledge Sources / B. Perception / 3. Representation
22168 Minds take in a likeness of things, which activates an awaiting potential
12. Knowledge Sources / C. Rationalism / 1. Rationalism
20224 Sensation prepares the way for intellectual knowledge, which needs the virtues of reason
12. Knowledge Sources / D. Empiricism / 5. Empiricism Critique
1860 Knowledge may be based on senses, but we needn't sense all our knowledge
13. Knowledge Criteria / B. Internal Justification / 5. Coherentism / a. Coherence as justification
22109 The fullest knowledge places a conclusion within an accurate theory [Kretzmann/Stump]
14. Science / D. Explanation / 2. Types of Explanation / k. Explanations by essence
11198 Definition of essence makes things understandable
15. Nature of Minds / C. Capacities of Minds / 1. Faculties
22107 Sensations are transmitted to 'internal senses' in the brain, chiefly to 'phantasia' and 'imagination' [Kretzmann/Stump]
15. Nature of Minds / C. Capacities of Minds / 2. Imagination
9098 Mental activity combines what we sense with imagination of what is not present
15. Nature of Minds / C. Capacities of Minds / 3. Abstraction by mind
9092 Abstracting A from B generates truth, as long as the connection is not denied
15. Nature of Minds / C. Capacities of Minds / 5. Generalisation by mind
9093 We understand the general nature of things by ignoring individual peculiarities
9097 The mind abstracts generalities from images, but also uses images for understanding
9095 Very general ideas (being, oneness, potentiality) can be abstracted from thought matter in general
9099 Particular instances come first, and (pace Plato) generalisations are abstracted from them
10508 Species are abstracted from appearances by ignoring individual conditions
16. Persons / F. Free Will / 1. Nature of Free Will
22111 Aquinas attributes freedom to decisions and judgements, and not to the will alone [Kretzmann/Stump]
16. Persons / F. Free Will / 3. Constraints on the will
1855 If we saw something as totally and utterly good, we would be compelled to will it
16. Persons / F. Free Will / 4. For Free Will
1861 The will is not compelled to move, even if pleasant things are set before it
1862 However habituated you are, given time to ponder you can go against a habit
1853 Because the will moves by examining alternatives, it doesn't compel itself to will
1849 Since will is a reasoning power, it can entertain opposites, so it is not compelled to embrace one of them
1856 Nothing can be willed except what is good, but good is very varied, and so choices are unpredictable
16. Persons / F. Free Will / 5. Against Free Will
1854 We must admit that when the will is not willing something, the first movement to will must come from outside the will
17. Mind and Body / A. Mind-Body Dualism / 1. Dualism
22105 The human intellectual soul is an incorporeal, subsistent principle
17. Mind and Body / A. Mind-Body Dualism / 4. Occasionalism
20700 Without God's influence every operation would stop, so God causes everything
18. Thought / A. Modes of Thought / 6. Judgement / a. Nature of Judgement
22108 First grasp what it is, then its essential features; judgement is their compounding and division
18. Thought / E. Abstraction / 1. Abstract Thought
10503 We abstract forms from appearances, and acquire knowledge of immaterial things
10509 Understanding consists entirely of grasping abstracted species
18. Thought / E. Abstraction / 2. Abstracta by Selection
10506 Mathematics can be abstracted from sensible matter, and from individual intelligible matter
18. Thought / E. Abstraction / 3. Abstracta by Ignoring
9094 Mathematical objects abstract both from perceived matter, and from particular substance
10505 We can just think of an apple's colour, because the apple is not part of the colour's nature
10504 Abstracting either treats something as separate, or thinks of it separately
10507 Numbers and shapes are abstracted by ignoring their sensible qualities
18. Thought / E. Abstraction / 8. Abstractionism Critique
9096 The mind must produce by its own power an image of the individual species
19. Language / C. Assigning Meanings / 3. Predicates
11206 The mind constructs complete attributions, based on the unified elements of the real world
20. Action / B. Preliminaries of Action / 2. Willed Action / a. Will to Act
23180 The will is the rational appetite
1847 The will must aim at happiness, but can choose the means
1857 We don't have to will even perfect good, because we can choose not to think of it
1846 The will can only want what it thinks is good
22. Metaethics / A. Ethics Foundations / 1. Nature of Ethics / g. Moral responsibility
1850 Without free will not only is ethical action meaningless, but also planning, commanding, praising and blaming
22. Metaethics / A. Ethics Foundations / 2. Source of Ethics / b. Rational ethics
22112 For humans good is accordance with reason, and bad is contrary to reason
22. Metaethics / B. Value / 1. Nature of Value / e. Means and ends
22494 We must know the end, know that it is the end, and know how to attain it
22. Metaethics / C. The Good / 1. Goodness / g. Consequentialism
1851 Good applies to goals, just as truth applies to ideas in the mind
23. Ethics / C. Virtue Theory / 1. Virtue Theory / b. Basis of virtue
23181 All acts of virtue relate to justice, which is directed towards the common good
23. Ethics / C. Virtue Theory / 2. Elements of Virtue Theory / d. Teaching virtue
8009 Aquinas wanted, not to escape desire, but to transform it for moral ends [MacIntyre]
23. Ethics / C. Virtue Theory / 2. Elements of Virtue Theory / i. Absolute virtues
23182 Legal justice is supreme, because it directs the other virtues to the common good
23. Ethics / C. Virtue Theory / 3. Virtues / b. Temperance
22399 Temperance prevents our passions from acting against reason
23. Ethics / C. Virtue Theory / 3. Virtues / c. Justice
23177 Justice directs our relations with others, because it denotes a kind of equality
25. Social Practice / D. Justice / 1. Basis of justice
23179 People differ in their social degrees, and a particular type of right applies to each
25. Social Practice / D. Justice / 2. The Law / c. Natural law
22114 Tyrannical laws are irrational, and so not really laws
23174 Natural law is a rational creature's participation in eternal law
22113 Right and wrong actions pertain to natural law, as perceived by practical reason
25. Social Practice / E. Policies / 1. War / a. Just wars
7291 For Aquinas a war must be in a just cause, have proper authority, and aim at good [Grayling]
25. Social Practice / F. Life Issues / 3. Abortion
5508 Aquinas says a fertilized egg is not human, and has no immortal soul [Martin/Barresi]
26. Natural Theory / A. Speculations on Nature / 7. Later Matter Theories / c. Matter as extension
16687 Bodies are three-dimensional substances
26. Natural Theory / C. Causation / 5. Direction of causation
11207 A cause can exist without its effect, but the effect cannot exist without its cause
26. Natural Theory / C. Causation / 9. General Causation / d. Causal necessity
1859 Even a sufficient cause doesn't compel its effect, because interference could interrupt the process
27. Natural Reality / D. Time / 1. Nature of Time / f. Eternalism
15202 Eternity coexists with passing time, as the centre of a circle coexists with its circumference
28. God / A. Divine Nature / 6. Divine Morality / b. Euthyphro question
23178 Divine law commands some things because they are good, while others are good because commanded
28. God / B. Proving God / 2. Proofs of Reason / b. Ontological Proof critique
21251 We can't know God's essence, so his existence can't be self-evident for us
28. God / B. Proving God / 3. Proofs of Evidence / a. Cosmological Proof
5614 If you assume that there must be a necessary being, you can't say which being has this quality [Kant]
21269 Way 1: the infinite chain of potential-to-actual movement has to have a first mover
21270 Way 2: no effect without a cause, and this cannot go back to infinity, so there is First Cause
21271 Way 3: contingent beings eventually vanish, so continuity needs a necessary being
21272 Way 4: the source of all qualities is their maximum, so something (God) causes all perfections
28. God / B. Proving God / 3. Proofs of Evidence / b. Teleological Proof
21273 Way 5: mindless things act towards an obvious end, so there is an intelligent director
29. Religion / B. Monotheistic Religion / 4. Christianity / a. Christianity
20211 Life aims at the Beatific Vision - of perfect happiness, and revealed truth [Zagzebski]
29. Religion / B. Monotheistic Religion / 4. Christianity / c. Angels
22106 Aquinas saw angels as separated forms, rather than as made of 'spiritual matter' [Kretzmann/Stump]
29. Religion / B. Monotheistic Religion / 4. Christianity / d. Heresy
16711 Heretics should be eradicated like wolves
29. Religion / D. Religious Issues / 2. Immortality / a. Immortality
23306 Humans have a non-physical faculty of reason, so they can be immortal [Sorabji]
1863 If the soul achieves well-being in another life, it doesn't follow that I do
29. Religion / D. Religious Issues / 2. Immortality / d. Heaven
4412 Those in bliss have their happiness increased by seeing the damned punished
29. Religion / D. Religious Issues / 3. Problem of Evil / a. Problem of Evil
21266 God does not exist, because He is infinite and good, and so no evil should be discoverable
21274 It is part of God's supreme goodness that He brings good even out of evil