The Basics: Some Familiar Territory Plato’s knowledge as memory, learning as remembering. Innate ideas. A priori knowledge. Logical “truths” that describe phenomena of the physical world (“A or not-A:” “The door is either locked or not-locked.”)

The Historical 400 BCE: The Greeks Plato, Aristotle, Pre-Socratics Collapse of palace-centered economies. New commercial classes. New democracy. Established power supported by old mythos replaced by new power based on logos. Need for new order (Plato’s metaphysics) CE: The Renaissance Descartes, Spinoza, Leibniz Waning authority of the Church. Schisms ( ). Protestant Reformation (1517 Luther’s 95 Theses). New sciences (Newton, Kepler, Galileo, Copernicus).

Nickolaus Copernicus (1473 – 1543 Poland) If all the planets orbit the sun, including Earth, then the human drama is not really at the center of God’s attention (human dignity?). But, thankfully, the moon clearly orbits Earth.

Galileo ( Italy) If Jupiter has moons that orbit it and not Earth, then…... The Inquisition: Explain Yourself The Sentence: Life imprisonment (at home)—dies 5 years later.

What does this have to do with Rationalism? Descartes ( France). Practicing Catholic. Just sent manuscript of The World to publisher (contained ideas that mirrored Galileo). Worried about the ability of oppressive, unbending religion to survive the challenge of science.

Hmmmm…..If I could only think of a way to continue exploring science without infuriating the Church What if I could show that science itself depended on some theological principles that recognize the authority of the Church?

Where Descartes’ Path Led Him How can Descartes reclaim the world (and science)? If then If there is an all-powerful, all-knowing, all-good God, then an evil genius cannot be calling all the shots. If then If an evil genius isn’t totally controlling me, then it is possible to find other truths.

The Challenge Can’t use math, can’t use body, and can’t rely on sense data about the world. a priori God must be found in a priori knowledge.

Step 1: Establish the Primacy of Some Innate Ideas Wax appears…. Wax smells…. Wax feels…. Wax sounds… Wax tastes…. Is it still wax? Is it the “same” thing? From where does the idea of “thingness” or “substance” come?

The Implications Sameness or identity is a priori knowledge (A=A). Substance is a priori knowledge. From Meditation I: Self is a priori knowledge. Descartes is “modern” in his reliance on reason over authority.

Descartes’ 1 st Argument: Argument from Perfection A being that doubts is an imperfect being. I doubt; therefore, I am an imperfect being. Yet I could know that I am imperfect only by having the concept of perfection. Therefore, I do have the concept of perfection. I could not have received the concept of perfection from something imperfect; therefore, my concept was not derived from myself. Therefore, my concept of perfection was derived from something that is perfect. Only God is perfect (i.e. God is perfection), so I derived my concept of perfection from him. Therefore, God exists.

So……. If God exists, I am not possessed by an evil genius.

Science safely rests on a godly foundation, and the soul is safe from science since the soul cannot be observed and measured.

Problems for Descartes “Commonsense” experience of reality doesn’t work. Cartesian experience of reality is counterintuitive.

And More Problems…. If substance is “absolutely independent,” then how can there be both an infinite substance and finite substances? How do the mind and body substances interact?

Baruch Spinoza ( Amsterdam) Like Descartes’ idea of substance, but not the contradiction between infinite and finite substances. So what if God were the only substance?

Spinoza: “Nature equals God” (pantheism). All things are expressions of God. One must love all things to love God. To love God is to have knowledge of him.

Gottfried Leibniz ( Germany) Didn’t like Spinoza’s pantheism and immanent God. Wanted a return to Descartes’ transcendent God (without Descartes errors).

Leibniz’s Principle #1: Principle of Identity All bachelors are men. 2+3=5. Either A or not-A. The cat is on the mat. Obama is president of the US. Leibniz is dead.

Leibniz’s Big Move: Sub Specie Aeternitatis (consider it from Gods’ point of view) If God is omniscient, omnipotent, omnipresent, and perfect and if God has a plan, then synthetic propositions are necessarily true from God’s point of view.

Leibniz’s Principle #2: Principle of Sufficient Reason Anything that exists exists for a reason and exists as it does for a reason. God saw all possibilities at the moment of creation and chose what and how to create. God makes no mistakes and leaves nothing to chance. The sky is blue because God made it that way. John is talking to his philosophy class about Leibniz right now because God made the world in a way that requires John to be talking to the philosophy class about Leibniz right now.

What does this mean? Just as “2+3=5” is necessarily true, so is “Obama is president of the US.” It can’t be any other way. The cat is on the mat…..and IT HAS TO BE.

Leibniz’s Principle #3: Principle of Internal Harmony An omnibenevolent God wants…. Maximum existence (Metaphysical Perfection). Maximum Activity (Moral Perfection). God considered all possibilities & arranged the individual parts to harmonize. World may appear imperfect to us, but it could be worse.

In what ways are Descartes, Spinoza, and Leibniz telling us about the nature of reality and the world “out there”? Descartes and physical laws. Spinoza and unity Leibniz and coherence

Origins of Perfection Infinity, Eternity, Circle, Equality, etc.? Sense data does not provide for knowledge and certainty? Logic and reason tells us about the world “out there”? Strengths of the rationalist approach? Weaknesses?