Notes for 8/25/2026

“Modern Philosophy”

 

Philosophy lounge

436

Eric Sotnak

 

No electronic devices (Blog)

 

Weekly Responses 50%  3 paragraphs or more

 

2 essays = 40%

 

10% attendance

 

Attendance Policy

10% Attendance

         Maximum of 12 absences before failing course

         You get 1.5 points for each day you come to class. There are 29 class meetings (= 43.5 points).

If you attend 24 class meetings, you will get 100% on your attendance grade (36 points). If you attend more than 24 class meetings (up to 29) you can earn 121% on your attendance grade.

In addition, extra credit points will be earnable at the end of the semester depending on how many people complete the course evaluation.

 

 

 

AI Policy

You may use AI in whatever ways you want in the course with the following restriction: You may never misrepresent the output of any AI tools as your own work, and you may not paste in any AI outputs as the main content for any assignment.

 

If you use any AI tools in completing any assignment, you must briefly state at the end of the assignment which tools you used and how you used them.

 

 

Why do you think people have eyebrows?

 

 

Aristotle

“The Philosopher”

 

 

 

Causation has 4 aspects:

1. Material

2. Formal

3. Efficient

4. Final (teleology = purposiveness)

 

-      The material cause of the pot is clay.

-      The formal cause of the pot is the shape imposed on the clay.

-      The efficient causes of the pot are the actions of the potter.

-      The final cause of the pot is “to hold stuff.”

 

 

It is somewhat fair to say that Modern philosophy is defined by the effort to eliminate teleological causation from a science of nature.

 

 

Material reality:

-      Fire

-      Air

-      Water

-      Earth

 

Basic elements have a natural order to them (as shown).

 

Things behave the way they do because of what they are made of.

Each element seeks its proper/natural place (its telos) in relation to the other elements.

 

 

Therefore, everything has exactly one natural motion which is defined by its telos.

 

Artificial motion (imparted from outside) dissipates, whereas natural motion does not.

 

Aristotelian physics has no law of inertia.

 

 

 

Celestial motion?

 

 

One explanation is that celestial objects are made of a stuff whose natural motion is circular (= quintessence, or ether)

(This preserves the rule that material composition determines movement and situation.)

 

Quintessence is incorruptible, eternal, unchanging, etc.

Circularity because the circle is the most perfect geometrical shape.

 

There is no universal physics for Aristotle.

There is one physics for terrestrial phenomena (the “sublunary sphere”) and a different physics for celestial phenomena.

 

A second explanation of celestial motion (which may harmonize with the first) is that all celestial objects (stars, planets, moon, sun) are embedded in perfect spheres made of quintessence. The spheres rotate (eternally) because they are made of quintessence.

 

But: a possible third explanation is that each sphere is eternally moved (via final causation) by a divine entity (demiurge). (Circular motion “strives” to realize the perfection of the demiurge.) The number of unmoved movers is unclear. Aristotle suggests both that there is only one, and that there is one per sphere.

 

The need for an “unmoved mover” is based on Aristotle’s apparent rejection of infinite causal regresses (though he accepts an infinite temporal regress).

 

Ptolemy: Ancient astronomer who modeled the heavens geometrically.

 

 

Ptolemism (Aristotelianism):

Geocentric model of the universe with Earth at center and moon and then planets and stars at the outside each having perfectly circular orbits.

 

 

Retrograde motion = apparent reversal of planets in their courses.

 

Retrograde motion was modeled by Ptolemaic astronomers using “epicycles” (literally, circles on circles).

 

 

Resulting Appearance:

 

Epicycles got multiplied and changed in various ways to try to improve the fit between prediction and observation. (“predictive adequacy”)

 

 

 

 

 

Another device astronomers used was the “equant point” (offset of the spheres from their center points)

 

 

                                                                                                                                                    (Made with Google Gemini)

 

At some point the question arises as to whether Ptolemaic models are literally true or whether they are mere convenient devices (“hypotheses”) whose sole purpose is predictive adequacy (“to save the phenomenon”).

 

It becomes accepted that a model doesn’t have to be literally true to be useful. It can be a mere hypothesis.

 

But the literal truth was reserved for the Aristotelian account.

 

Copernicus = Polish astronomer who replaced a geocentric model with heliocentric model.

(Aristarchus proposed a heliocentric model in the 3^rd century BCE – probably to explain eclipses?)

 

 

 

 

But Copernicanism violated basic laws of Aristotelian physics:

-      It required more than one natural motion (the Moon moves around Earth but also moves with Earth around the Sun)

-      There is no explanation in terms of what the moon is made of for the Moon’s double motion

-      There is no explanation for the Earth’s rotational motion

-      There was no explanation for why things fall straight down rather than far West of their release point

 

 

The problems of Ptolemism were initially no worse than the problems of Copernicanism.

 

That changed.