Descartes and Buddies “To be or not to be, that is the question”

As the world shifts

Contradictions Carpe diem Carpe diem (seize the day) (seize the day) Momento mori Momento mori (remember you must die) (remember you must die) Based on the concept that life is brief Based on the concept that life is brief

Life is a Theater, therefore, Shakespeare All the world’s a stage/And all the men and women merely players:/They have their exits and their entrances;/And one man in his time plays many parts. As You Like It All the world’s a stage/And all the men and women merely players:/They have their exits and their entrances;/And one man in his time plays many parts. As You Like It Life’s but a walking shadow, a poor player/That struts and frets his hour upon the stage,/And then is heard no more; it is a tale/Told by an idiot, full of sound and fury,/Signifying nothing.” Macbeth Life’s but a walking shadow, a poor player/That struts and frets his hour upon the stage,/And then is heard no more; it is a tale/Told by an idiot, full of sound and fury,/Signifying nothing.” Macbeth

If it isn’t a stage, what is it?

Idealism and materialism IDEALISM IDEALISM Some philosophers believed that all that exists is, at bottom, spiritual in nature Some philosophers believed that all that exists is, at bottom, spiritual in nature MATERIALISM MATERIALISM Others believed that all real things come from concrete material substances—particles of matter (even the soul starts with movement of tiny particles in the brain) Others believed that all real things come from concrete material substances—particles of matter (even the soul starts with movement of tiny particles in the brain)

Motion Wins Newton applied motion to all changes on earth and in space: principles of universal gravitation and the motion of bodies Newton applied motion to all changes on earth and in space: principles of universal gravitation and the motion of bodies Everything was thus governed by the same unbreakable laws (mechanisms). Everything was thus governed by the same unbreakable laws (mechanisms). Possible to calculate every natural change with mathematical precision. Possible to calculate every natural change with mathematical precision.

The world as a machine If so, then everything that happens is predetermined (“It’s written in the stars”) If so, then everything that happens is predetermined (“It’s written in the stars”) Bye-bye free will Bye-bye free will Everything is a product of mechanical processes, even our thoughts and dreams Everything is a product of mechanical processes, even our thoughts and dreams

He was convinced that knowledge is attainable only through reason He was convinced that knowledge is attainable only through reason Can’t trust old information Can’t trust old information Can’t trust senses Can’t trust senses Can this be Plato again? Can this be Plato again? Long live the rationalists. Long live the rationalists.

If nothing is “true,” what do you do? Come up with the new philosophical system that will direct the world from this moment forward. Come up with the new philosophical system that will direct the world from this moment forward. How about two questions: How about two questions: What can we know? (certain knowledge) What can we know? (certain knowledge) What is the relationship between body and mind? What is the relationship between body and mind?

Skepticism Is it true that we know nothing? Skeptics thought so. Is it true that we know nothing? Skeptics thought so. But Descartes thought: If natural sciences develop a method to provide exact descriptions of natural sciences, why can’t philosophy? But Descartes thought: If natural sciences develop a method to provide exact descriptions of natural sciences, why can’t philosophy? The big question: In a mechanistic view, what’s the relationship between the body and the soul? The big question: In a mechanistic view, what’s the relationship between the body and the soul?

The Soul Before the 17 th century: Before the 17 th century: Soul was “breath of life”Soul was “breath of life” Pervaded all living creaturesPervaded all living creatures Soul and spirit meant “breath” or “breathing”Soul and spirit meant “breath” or “breathing” Aristotle saw soul everywhere as the “life principle”—could not be separate from the bodyAristotle saw soul everywhere as the “life principle”—could not be separate from the body

Big Question: If the body is a machine, surely the soul could not be part of this body machinery. If the body is a machine, surely the soul could not be part of this body machinery. WHAT IS THE SOUL, THEN? WHAT IS THE SOUL, THEN?

Mind / Body Mind / Body I decide to lift my arm I decide to lift my arm I decide to run for the bus I decide to run for the bus I think of something sad I think of something sad The arm lifts itself The arm lifts itself My legs start moving My legs start moving I start crying I start crying

Discourse on Method We cannot accept anything as being true unless we can clearly perceive it We cannot accept anything as being true unless we can clearly perceive it Break down compound problem into as many single factors as possible Break down compound problem into as many single factors as possible Point of departure comes in simplest idea of all Point of departure comes in simplest idea of all Philosophy should go from the simple to the complex Philosophy should go from the simple to the complex Ensure new insight with constant vigilance (mathematical in model) Ensure new insight with constant vigilance (mathematical in model)

Doubt everything When we dream, we feel that we are experiencing reality When we dream, we feel that we are experiencing reality “When I consider this carefully, I find not a single property which with certainty separates the waking state from the dream…how can you be certain that your whole life is not a dream?” Descartes “When I consider this carefully, I find not a single property which with certainty separates the waking state from the dream…how can you be certain that your whole life is not a dream?” Descartes

What else is true? Descartes concluded that in his mind was a clear idea of a perfect entity. He’d always had this idea, so it clearly did not come from himself, since he was imperfect. Therefore, the idea of a perfect entity must have originated from that perfect entity itself: God. God’s existence, then, was as self evident as his own thinking. Descartes concluded that in his mind was a clear idea of a perfect entity. He’d always had this idea, so it clearly did not come from himself, since he was imperfect. Therefore, the idea of a perfect entity must have originated from that perfect entity itself: God. God’s existence, then, was as self evident as his own thinking.