RENE DESCARTES 1596-1650

1. RENE DESCARTES1596-1650 • French philosopher, mathematician and physical scientist (optics, physics, physiology) • Father of Modern Rationalist Philosophy • Initiates intellectual break with ancient and medieval thinking • Appeals to analytical reason and logic to investigate the nature of both mind and nature in the context of developing science

2. Descartes’ Scientific Contemporaries • Copernicus (Polish; 1473-1543) • Astronomy: Heliocentric solar system • Challenge to Church-endorsed Geocentric universe • Francis Bacon (English; 1561-1626) • Development of the scientific method • Galileo (Italian; 1564-1642) • Mathematician, Physicist & Astronomer; Copernican; challenge to Church • Kepler (German; 1571-1630) • Discovered laws of planetary motion • Boyle (Irish; 1627-1691) • Developed experimental chemistry; worked in mechanics, medicine, hydrodynamics • Newton (English; 1642-1727) • Fundamental laws of physics; classical mechanics

3. DESCARTES’ QUESTIONS • Is the mind different from matter? • Should we adopt the scientific method to advance knowledge? • What can we know with certainty?

4. Descartes’ Dualism • Two Kinds of Substance • Material Substance • Essence = to be in space without thinking • Mental Substance • Essence = to think without being in space • Pin Cushion Model of Object • Substance • Attributes (forms) • Essential • Accidental

5. Role of Substance • Bind and Unify Attributes • Persist through change • Individuate similar objects • Serve as the subject of thought

6. Role of Attributes • Constitute qualities and relations of objects • Bases of similarity and difference among objects • Fluctuate in Change • Elements recognized in sensation and thought

7. Types of Attributes • Essential • Loss = destruction of object • Determine objects kinds, types, categories, genus or species • Critical to our understanding of the object (triangularity of triangles)

8. Types of Attributes • Accidental • Fluctuate in change consistent with persistence • Not critical to our understanding of the object (the color of a triangle)

9. Arguments for Dualism • Conceivability • I can conceive of my mind as existing only if I also conceive it as thinking • So, thought is an essential attribute of my mind • But I can conceive of my mind as existing without an extended body

10. Conceivability Argument • Hence, extension and body are not essential to the mind • Hence, it is possible that the mind exist without a body • Hence, the mind must be a different substance from the body. Dualism must be true!

11. Objection • It is a mistake to infer from the fact that body is not essential to mind that the mind cannot exist without a body • My mind may not need my body to exist, but it needs some body to exist

12. Contrast: Triangles do not have color among their essential attributes. But every real triangle must have some color or other. Perhaps minds are related to their bodies in the way that triangles are related to their colors.

13. Since we do not think that dualism with respect to triangles is true, neither need we say that dualism with respect to the mind is true.

14. Argument From Thought for Dualism • All Thoughts and ideas are Intentional • I.e. Ideas are About things that are typically real things but which can be nonexistent things • Some thoughts and ideas are Conscious

15. It is inconceivable, and hence impossible, that selected material objects such as rocks are intentional or conscious. • Hence, there is nothing in matter that allows for intentionality or consciousness

16. Hence, intentionality and consciousness can only occur in something that is immaterial. • Hence, dualism is true.

17. Objection • It is true that rocks can be neither intentional nor conscious • However, from that it does not follow that no sort of material object can be intentional or conscious

18. It seems possible that intentionality and consciousness emerge from material complexity that rocks lack but things like brains have. • In that case, intentionality and consciousness are not grounds for endorsing dualism • However, this raises the question: are artificial minds possible?

19. Descartes on Knowledge and Science • Can fallible human beings, using only their own intellectual powers, establish genuine knowledge of what is universally and necessarily true? • For example: • Knowledge of mathematical truths, laws, principles • Knowledge of natural general laws and principles • Eg: Heliocentric solar system

20. Descartes vs. the Skeptic • Working definition of Knowledge = true belief based upon evidential certainty • Contrast true “lucky” belief vs. true certain belief • Certainty and evidence • How much evidence does knowledge require? • Consider evidence as probability under multiplication • Consider knowledge as tall building requiring a firm foundation

21. Both Descartes and the Skeptic agree that knowledge = true belief based on evidential certainty • Both also agree that there are only two kinds of evidence: • Empirical [or A posteriori” (from the Latin: “from the latter”)] evidence = evidence based upon observation (sensation/perception) • A priori (from the Latin: “from the former”) evidence = evidence based upon pure reasoning apart from observation; provable from absolute truths knowable by reason alone. • However, the Skeptic denies the possibility of evidential certainty, claiming that neither empirical nor a priori evidence admits of certainty

22. The Skeptic’s Argument • Meditation I: Descartes' provisional argument on behalf of the skeptic • Sensation/perception does not provide evidential certainty because of • Illusion: hence, no knowledge of attributes • Hallucination : hence, no knowledge of particular existence • Dream Hypothesis: hence, no knowledge of existence of the universe generally • Pure reason does not provide evidential certainty because of • Evil Demon hypothesis • Hence, certainty is impossible • Hence, knowledge is impossible

23. Descartes’ Reply to the Skeptic in Meditation II • The Cogito • Cogito, ergo sum • Hence, each person can be certain about • His/her own existence • His/her own current ideas (psychological states), I.e. the content of his/her own ideas/story/theory about the external world • Such certainty is limited to “what is inside,” to “what the inside ideas/story/theory says about the external world” • This does not address the question as to the truth of the ideas/story/theory

24. Descartes on Knowledge of the External World • Arguments for the existence of God and, hence, against the Evil Demon Hypothesis • Ontological Argument • Formal and Objective Reality • If God exists as the creator/designer of our minds, then our ideas/theories of the external world must be generally (probably) true. • This falls short of certainty, but is nevertheless sufficiently evident for knowledge. • Objection to Descartes: • The Cartesian Circle: To refute the Demon Hypothesis by reasoning to the existence of God circularly presupposes that the Demon Hypothesis is false. It begs the questions!

25. Problems with the Cogito • Evil Sophomores • Classification of present sensations • What shade of red was that? • Unconscious ideas • Rhymes: how did you do that? • Unattended Channel Experiment • Implicit Beliefs in competition with Explicit Beliefs • Eg. Have you seen my glasses? Did you put them on the kitchen table? Oh! Yes, of course, I did! • More interesting: Video of Tamar Gendler and Eric Schwitzgebel. We harbor attitudes (biases) of which we are unaware that influence our behavior and are inconsistent with what we explicitly and sincerely state our beliefs to be. See Mahzarin R. Banaji’s for her research on implicit attitudes

26. Problems with the Cogito(Continued) • The Problem of solipsism • “solus” = Latin for “alone” • Am I alone in the universe? • Is evidence of other minds also evidence of artificial minds?