St. Thomas Aquinas (1225-1274) • Youngest son of wealthy merchant who joined the Dominicans against the wishes of his parents • One of first philosophers/theologians to take seriously Aristotle and Islamic Philosophy • Represents the apex of the Medieval mind and achieved the pinnacle of the Medieval project • An extraordinary man: • Brilliant • Prolific writer • Desired knowledge above all else . . . • Great Saint • Stopped writing in 1273; “It’s all straw” • Died in 1274 and canonized in 1323 • Recognized as a Doctor of the Church
Reliable when: Story fits with personal experience (it’s likely) Names the author, who is an authority Right in the past about related material Other credible sources believe it; often quoted Not meant to entertain alone, but to instruct or inform The Bible: Relates with personal experience (human condition) Moses, David, the Prophets and the Apostles were all eye-witnesses Many predictions right; definitely filled with sound psychological and ethical advice Believed by countless numbers, including some of the world’s smartest people Clearly meant to instruct and inform (and entertain . . . ) What is a reliable printed source? So, do you believe the Bible? Does everyone? Does everyone believe in reason? What is the relationship between faith and reason?
I.1.1: Is philosophy all that is needed to reach our end (happiness)? Theology Philosophy End (Happiness is being with God) Humans Reason can make many things clear, such as the truth about math, the natural sciences, what is good, how to be virtuous . . . But some things discovered by reason (such as things about God), would be hard for everyone to understand by reason alone, and even then it may be filled with error. So, . . . What is needed in addition to Philosophy?
I.1.2: Is Sacred Doctrine actually a science? Questions: What is a science? What makes a science true? Assumed: Every science either begins in self-evident principles (e.g.: the law of non-contradiction; the whole is greater than its parts; rocks always fall?; Rocks are not alive?) or begins in the conclusions of another science (optics depends upon principles discovered and supported by geometry; music depends upon principles discovered and supported by arithmetic). What kind of science is Physics? Biology? Psychology? Philosophy? Is theology based upon self-evident principles or upon something else? What is that something else? Will everyone accept revelation as true? That is, will everyone accept what the Bible says is true? (e.g., that God exists; God created the world; God is eternal). What science also reaches some of those same conclusions? Will everyone accept the conclusions of philosophy? What if only valid deductive arguments are given and all the premises are true?
I.1.4: Is Theology a speculative or a practical science? Theology is both (but its mostly speculative) I.1.5: Is Theology the best (most noble) science? • The best speculative science is: • Most certain (foundation is certain) • Studies the most important subject (that which has greatest worth) Theology starts with God’s revelation – can’t be wrong. Human reason is often wrong. Theology studies things that transcend human reason. What can be more worthy than that? The best practical science is: 1) Concerned with the highest purpose Theology has the greatest purpose in mind – eternal bliss. What is more important than that? Does theology depend upon philosophy and the other sciences? If so, in what way? Does this dependence ‘cheapen’’ theology?
I.1.6: Is theology the same thing as wisdom? Yes . . . But the real interesting idea in this article is that ‘lesser matters should be judged in the light of some higher principle.’ So, who has the right to judge another . . . The architect or the day laborer? The doctor or the patient? The theologian or the philosopher? The physicist? The biologist? Given this principle, is Aquinas correct when he writes in Objection 2: The principles of other sciences either are evident and cannot be proved, or are proved by natural reason through some other science. But the knowledge proper to this science comes through revelation and not through natural reason. Therefore it has no concern to prove the principles of other sciences, but only to judge of them. Whatsoever is found in other sciences contrary to any truth of this science must be condemned as false. Whatsoever is found in other sciences contrary to any truth of this science must be condemned as false.
I.1.8: Is theology really something that can be argued? • Yes, if your opponent believes at least some of theology’s starting principles – which are revealed through revelation. • However, Aquinas writes: If our opponent believes nothing of divine revelation, there is no longer any means of proving the articles of faith by reasoning. • So,how can a theologian prove something about God to someone who doesn’t believe in what the Bible reveals? • If theology is the ‘queen of the sciences’ why does theology need to make use of philosophy? • Which has the greater role in theology – arguments from philosophers or arguments from scripture? Why?
ST I.2.1: Is the existence of God self-evident? When is a proposition self-evident? Any proposition is self-evident when the predicate is included in the essence of the subject. This basically means that the predicate is saying the same thing as the subject. Can you think of an example? Man is an animal. Why is this self-evident? What are the two types of self-evident propositions? What are examples of each? A proposition isself-evident in itself and to us if everyone knows it – like the difference between being and non-being or the whole and the parts. A proposition isself-evident in itself but not to us when the predicate is included in the subject, but this fact is not know to all people but only to the learned. For example, ‘an incorporeal object does not take up space.’ How about this one . . . ‘God exists.’ Is this self-evident?
Yes! What do you think of the following quotation: "The invisible things of Him are clearly seen, being understood by the things that are made" (Rm. 1:20). What does it mean if true? ST I.2.2: Can God’s existence be demonstrated? • What are the two ways something can be demonstrated? • Through the cause (a priori). In this situation you argue from what is known absolutely (the cause to its effects). • Ex: if you have Lou Gerigh’s Disease (ALS), you will gradually lose muscular control of your extremities (hand and feet), then your limbs, and finally your ability to speak and swallow. • Through the effect (a posteriori). In this situation you argue from what is known prior to us (the effects to the cause). • Ex: if you gradually lost muscular control of your extremities, then limbs, and you are finding it hard to speak or swallow, you have Lou Gerigh’s Disease. • How do you prove the existence of atoms, protons and neutrons? • How do you prove the former existence of your great-grandfather? • How do you prove the actual existence of the love your parents have for you?
ST. I.2.3: Does God exist? YES! But don’t forget some of the points that were made before . . . Many of the claims of revelation can be demonstrated by human reason (I.1.8) Self-evident principles exist; however some are not known to be true unless you study them carefully (I.2.1) We can know that God exists because we know his effects (I.2.1 and I.3.2) Everyone has some vague idea of God, even if it is only dimly understood (I.2.1.reply 1) The names given to God are understood through his effects (I.2.2.reply 2)
In general, each of the Five Ways essentially depends upon the same a posteriori argument: • (P1) If there is no God, then the effects that only God could produce would not exist. • (P2) The effects that only God could produce do exist. • (C) Therefore, God exists. • This argument is a modus tolens (MT), which is a valid logical form. Remember, the definition of a valid argument: if the premises are true the conclusion also has to be true. • So, if Aquinas can prove P1 and P2 are true, then any rational person must accept the conclusion, that God exists. • So, are the premises true? How do you know? • Aquinas claims that P1 is true because it is both self-evident and it is supported by reason, for if some particular cause does not exist then the unique effect(s) that follow from that particular cause cannot exist. • Aquinas claims that experience (our senses) prove that P2 is true. • So, God exists.
In particular, Aquinas’ arguments depend upon the following points: • 1. The Law of Non-Contradiction never fails. The LNC affirms that two mutually contradictory properties cannot exist at the same time (e.g., it cannot be true that there is a first cause and that there is not a first cause.) • 2. Empirical Data (e.g., that motion and causality exist). • 3. Several other self-evident principles (e.g., ‘whatever is in motion is put in motion by something else in motion’, ‘there cannot be in infinite regression of motion’, or ‘nothing can cause itself to be’). • So, given the law of non-contradiction, there are only two possibilities: • A) God does not exist • B) God exists • Given (2) the empirical data and (3) the self-evident principle, the conclusion (A) that God does not exist is impossible. • Thus, the only logical answer is that God exists.
The argument from Motion (the First Way): • The cosmos is in motion (known by sense experience) • Whatever is in motion is put in motion by another (nothing can move itself) • a) Motion is the reduction from potency to act (known by definition) • ex. Fire makes wood (potentially hot) into a bonfire (actually hot) • b) The same thing cannot be both actual and potential in the same way • ex. What is actually hot cannot also be potentially hot in the same way • c) Therefore, nothing can move itself (follows from 2a and 2b) • 3) There is no infinite regression of motion – for if an infinite regression were possible there would be no first mover and hence no other movers either • ex. If there was no hand to move the staff, the staff would not move • Therefore, an Unmoved Mover – something that sets all things in motion but is not moved itself – must exist. This must be so or there would be no motion – which is absurd. • This unmoved mover is what we call God.
Can you explain any of the remaining 5 Ways?: What is the empirical data? What is the self-evident principle? Does the argument work?