Perception of Reality

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Our sensory organs (which we have established have limitations) gather information from stimuli in the

environment such as light or sound waves.

Our body converts the stimuli into neural signals that travel through our nerve cells to

our brains. (Transduction)

Our brains interpret the signals and create meaning. Sometimes, the complexity of the signals means it is difficult for our brains to

perceive with full accuracy.

Finally…each person has a different set of eyes and a different brain. If our brains are perceiving reality, and we each have

different brains, how similar are our realities, really?

Reality:“The world or the state of things as they actually exist, as opposed to an idealistic or notional idea of them.”

Pair-Share:

How do we each form an understanding of reality?

Is The Earth Flat?

Where does our understanding of the world come from?

1. Personal Experience: our first-hand sensations and experiences of the environment.

2. Authorities: certain people are culturally trusted: parents, teachers, highly educated professionals, and government

leaders.

3. Factual Evidence: has it been studied, tested, published, and declared to be a fact?

4. References: can you read about it in books that society considers to be reliable?

5. Culture/Tradition: This category is related to authority. Our cultural traditions and religious beliefs can influence

what we believe to be true.

Is The Earth Flat?Until sometime near the end of the 15th century (Columbus

sailed in 1492), the vast majority of people believed the Earth was flat. This idea formed a common world view and

was supported by reasoning and evidence.

• Authorities: Teachers taught that the world was flat. • References: Some scientific experts wrote opinions

supporting the belief that the world was flat. (Others, like Galileo, opposed this belief, but were silenced by the Catholic Church).

• Factual Evidence: No one had circumnavigated the earth. (Ferdinand Magellan sailed around the world between 1519-1522.)

• Personal Experience: From a normal vantage point, the earth looks flat.

Is The Earth Flat?Today, we believe that the world is round, and just like the

ancients, we base this belief on facts and experience. Every year, humanity discovers new things. How different will our

collective understanding of reality look 100 years from now?

• Authorities: My parents and teachers all agree that the earth is round.

• References: I read about this in science textbooks and I saw it in reputable TV documentaries about the planet and the solar system.

• Factual Evidence: I have seen photographs taken from outer space that show that the earth is round.

• Personal Experience: I have flown across the world in an airplane and have seen the curved horizon line of the planet.

The story of the “elephant in a dark room”

Multiple Perspectives“Multiple perspectives” means that we each experience reality from different points of view: through the lens of

different cultures, histories, religions, families, and schools. All disagreement in the world is the result of seeing the

world (including events, ideas) from different perspectives.

Pair-Share:How can we use our understanding of multiple

perspectives to explain human behavior?

History’s Great Philosophers tackle the question of reality

Plato’s Allegory of the CavePlato’s famous allegory is about the perception of a

limited reality. Imagine prisoners trapped in a cave for their entire lives. In the cave they can see shadows, but not the source of the

shadows. Because they have no knowledge of fire or of

the objects casting the shadows, the shapes they see on the wall and the

echoes they hear are the only experiences they have to create an understanding

of reality with.

Video 1

Rene Descartes’ Evil DemonIn the 17th century, Descartes came up with a thought experiment: he believed

that God created the world…but what if everything we see and experience is a vision created by -not a god- but an all-

powerful, evil demon? He thought, “what if the demon is controlling my mind,

and creating everything I experience?”

The modern version…

…the “brain in a jar.”

Rene Descartes’ Evil Demon

Descartes tried to think of something an evil demon could never

deceive him about. He decided that he cannot

be deceived into thinking that he does

not exist, because if he is thinking, he must be

existing. One must exist in order to think, so if you are thinking, you know for certain that

you exist!

Hume’s Idea of Causality

Hume was very different than Descartes: Descartes believed that our minds are the basis of truth, while Hume believed that experience is the

basis of truth. He asked, “if something happens repeatedly (like the rising of the sun), does it mean it is true that it will always rise?” He concluded that past experiences do not predict the future: our belief that the future

will resemble the past is a matter of habit.

We cannot imagine things we have never experienced! Every idea we create is a combination of things we have seen. Also…Facts can never be proven from

secondhand knowledge: they must be discovered or inferred

from personal experience.

Egocentric PredicamentThe “egocentric predicament” is the problem of not

being able to view reality outside of our own perceptions. (I don't know anything about the world,

other than what is given to me).

We are like the prisoners in Plato’s Allegory of the Cave:

the only reality we know is the one based on our experiences

(despite the fact that there could be a different reality

beyond what we are able to perceive!)

The PhaneronCharles Sanders Pierce came up with the term

“phaneron” to describe reality as it is filtered through our perceptions. He said that reality as we see it

and true reality are two separate things.

Technically, we can't prove that

anything exists...because in the end, all of the information

we acquire is the product of our

own minds!

Solipsism & RealismA solipsist is someone who believes that everything we experience is a

product of our minds. Thus, if I cease to exist, everything else ceases to

exist as well.

A realist is someone who believes that reality exists separately from our

minds. Thus, if I cease to exist, the outside world continues existing

without me.

However, it is impossible to prove that reality exists separately from our minds! We just believe it to be true.

Is it true that…

…?