Descartes: Part 2 - The Search for Certainty

Descartes' Doubt and the Search for Certainty

Initial Doubts (Meditation 2)

• Descartes expresses deep skepticism, feeling lost and unable to find certainty.

• He resolves to discard anything admitting of the slightest doubt, treating it as wholly false.

• He seeks one certain, unshakeable truth, comparing this endeavor to Archimedes' search for a fixed point to move the Earth.

From Doubt to Certainty

• Descartes initially seems trapped in doubt's stalemate.

• In Discourse on Method, he realizes that doubting itself implies existence: "Cogito, ergo sum" – "I think, therefore I am."

• This intuition strikes him with undeniable clarity, becoming his foundational truth.

• He believes this truth is unshakable and will serve as the basis for building knowledge.

• In Meditations, he takes a different approach to overcoming doubt.

The Argument from Deception

• Descartes considers the possibility of being deceived by a demon.

• He understands that being deceived necessitates existence; one cannot be tricked if one does not exist.

• Saint Augustine reached a similar conclusion 1300 years prior: "Si fallor, sum" – "If I am deceived, then I exist."

• Descartes insists this is an intuition, not a syllogism, but it can be structured as an argument:

  1. If I am deceived, then I must exist.

  2. I am deceived.

  3. Therefore, I must exist.

• "I am, I exist" becomes Descartes' indubitable claim.

• He asserts that even an evil demon cannot make him nothing while he thinks he is something.

Implications of "I am, I Exist"

• "I am, I exist" is the first building block of Descartes' philosophical project.

• He questions the nature of this "I" and seeks to understand it properly to avoid errors.

• He revisits his prior beliefs about himself to eliminate anything questionable.

• He returns to the "drawing board of doubt" to define the "I" that must exist.

The Thinking Thing (Res Cogitans)

• Descartes considers the possibility of a malicious deceiver tricking him in every way.

• He can no longer trust his prior conception of himself as merely a body.

• The only thing he can confidently grasp is his mind and its thoughts.

• He affirms that he can grasp nothing more easily than his mind.

• He defines himself as a res cogitans, a thing that thinks, or a thinking thing – a mind.

The Nature of the Thinking Thing

• A thinking thing is something that doubts, understands, affirms, denies, wills, refuses, senses, and has mental images.

• Descartes argues that he can doubt the existence of his body but not his mind.

• He concludes that the mind could exist without the body, leading to the mind-body problem.

The Existence of God and the External World

• Descartes turns to the question of God to determine if the external world exists.

• If he can prove God exists, he can guarantee the existence of the world (God's creation).

• Without proving God's existence, he can only be certain of his own existence as a pure mind.

• He presents two arguments for God's existence: the trademark argument and the ontological argument.

• Both arguments begin with Descartes' idea of God.

The Trademark Argument

• Premise: Descartes has an idea of God as a supremely perfect being.

• Ideas can be adventitious (from experience), fictitious (invented), or innate (ingrained).

• The idea of God cannot be adventitious because God is not an extended substance.

• The idea of God cannot be fictitious because an imperfect being cannot form the idea of a perfect being.

• Therefore, the idea of God must be innate.

• If it is innate, it must have come from God Himself; therefore, God exists.

• Descartes claims God placed this idea in him as a "mark of the craftsman stamped on his work".

The Ontological Argument

• Premise: Descartes has an idea of God as a supremely perfect being.

• Something that really exists is more perfect than something that exists only in the mind.

• If God exists only in the mind, then He would lack real existence and would not be supremely perfect.

• But, by definition, God is a supremely perfect being.

• Therefore, God must really exist, not just as an idea in the mind.

afafsfafsExplanation of the Ontological Argument

• For Descartes, God's essence implies His existence.

• Just as a triangle's essence necessitates angles equaling two right angles, God's essence as a supremely perfect being necessitates existence.

• Existence is a necessary aspect of perfection; a supremely perfect being cannot lack existence.

• Existence is an essential attribute of God's nature, inseparable from Him.

The Existence of the World

• After establishing God's existence, Descartes addresses the world's existence.

• The idea of God implies a supremely perfect being whose goodness is complete; therefore, God cannot be a deceiver.

• Since God is not a deceiver, the physical world (God's creation) must truly exist.

• God guarantees that whatever Descartes perceives clearly and distinctly is true.

• He concludes that the physical world, including his body, exists.

• Thus, Descartes demonstrates (1) his existence, (2) his existence as a mind, (3) God's existence, and (4) the world's existence.

• This is the metaphysical foundation Descartes sought.

What the Mind Can Grasp about the World

• Descartes uses the wax argument to show that knowledge of physical objects comes from reason, not the senses.

• He describes a piece of wax with its initial properties: taste, smell, color, figure, size, hardness, coldness, sound.

• As the wax is heated, these properties change or disappear.

• Yet, the same wax remains.

• Therefore, the essence of the wax is not in these sensory properties.

The Essence of Physical Things

• The essence of physical things cannot be their color, shape, or texture because these change.

• What the mind perceives as the essence of physical things is that they take up space.

• The attribute of occupying space remains constant even when sensory properties change.

• Descartes uses the term res extensa to refer to extended things, or things that take up space.

• Extension is the main attribute of physical things.

Cartesian Dualism

• Reality consists of two kinds of substances: res cogitans (thinking things/minds) and res extensa (extended things/bodies).

• Minds do not occupy space and have the attribute of thought.

• Bodies have the attribute of extension, meaning they occupy space.

• Thinking things and extended things are essentially distinct.

• Only humans are a combination of both substances.

• God is an infinite thinking thing.

The Mind-Body Problem

• How do mind and body interact, given that minds do not occupy space and bodies do?

• Descartes believed the mind is seated in the brain, "the seat of intelligence."

• He mistakenly assumed the pineal gland connects mind and body, allowing the mind to control the body.

• Perceptions travel from the eyes to the pineal gland, which then allows fluids to pass to the muscles to produce a response.

• In reality, the pineal gland produces melatonin, controlling sleep patterns.

The Close Union of Mind and Body

• Descartes insists that the mind is not merely present in the body like a sailor in a ship but is conjoined or intermingled with it.

• Sensations like pain, hunger, and thirst demonstrate this close union.

• If the mind were separate, it would perceive damage to the body intellectually, like a sailor seeing damage to a ship.

• Instead, we have confused sensations arising from the union of mind and body.