In "Phaedo", Plato used Socrates to propose the conclusion that the soul is immortal, and put forward five views on this. The premise of this conclusion is based on Plato's recognition that human beings are composed of body and soul, and the soul must exist and is invisible.

I read the version of "Phaedo" translated by Mr. Yang Jiang. "This dialogue is a conversation Socrates had with a group of friends in the Athens prison on the day he was serving his sentence; it talked about the issue of life and death, mainly about the soul. The entire dialogue was narrated to Ichi by Phaedo, who participated in the conversation. The location of the story is in Frius, because Ichi is from that place." (Excerpted from this book)

Yale University professor Shelly Kagan questioned each of these five views and finally argued. , the soul does not exist. At the beginning of the course, Shelly said that there are some phenomena that physicalists cannot explain scientifically, such as channeling, but this just means that they cannot be explained at this stage. The "dualists" claim that all this can be explained by the existence of the soul, but they can only state this result, but cannot prove how to explain it with the soul. Those who have had "near-death" experiences cannot actually prove that the soul actually exists. After all, if we have never experienced death, how can we truly know that the soul exists? In this sense, I don’t believe in the existence of a soul either.

? Shelly’s argument intensified my “existing viewpoint tendency”. The argumentation process is extremely exciting. The following are my MOOC study notes. Share with everyone.

? Questions and refutations about the views and conclusions of "immortality of the soul" in Plato's "Phaedo":

1. The argument from the nature of the forms)

Plato believed that only the soul can think and recognize ideas or forms. There are two premises to satisfy this assertion: 1. Ideas or forms are eternal and non-material entities; 2. Eternal and non-material entities can only be recognized and understood by eternal and non-material entities;

From the above premise, it can be concluded that there are and can only be eternal and non-material entities that can recognize, understand and grasp concepts or forms.

An example rebuttal to the second premise: Zoologists do not need to become the animals themselves to study animals.

2. The argument from recycling (The argument from recycling)

Plato believes that, in layman’s terms, the soul is recycled. That is to say, the human body is new, but the soul in it originally existed before the body. The soul is immortal.

Shelly first affirms the fact that all things are cyclical. For example, the atoms that make up things exist before the constituents. After the constituents decompose, the atoms are not destroyed but constitute other things, which is considered a cycle. . The second question is, even if the soul really exists, how can we prove that the soul must be the part that is recycled like an atom? (Personally, I think the examples given by the professor in questioning this point are actually very weak. However, proving something that may not really exist is itself a weak thing.)

3. Regarding the "Reminiscence Theory" "(The argument from recollection)

? Plato believes that the soul is immortal, so the ideas or shapes recognized by the soul itself will not disappear. People's reflections and expressions of some things come from the guidance of the soul. .

Shelly retorted that people can also recognize ideas or forms through things in the real world. They do not need to use the so-called soul that retains previous cognition of forms to recognize and understand forms. Mutually.

4. The argument from simplicity

? Plato believes that the soul will not dissipate because it is the simplest, most single and pure thing, and cannot be Possibility of decomposition.

The establishment of this conclusion requires three premises: 1. Only things with a structure can be destroyed; 2. Only things that can be changed have a structure; 3. Intangible things cannot be changed; from this, Intangible things cannot be destroyed. The soul is intangible, so the soul cannot be destroyed.

Shelly questioned that to get this inference, it must be clear. What is the definition of intangible? The word invisible itself has three definitions: 1. Can not be seen; 2. Can not be observed by the five senses; 3. Can not be detected.

In response to the first definition, Shelly gave the example of music and harp. Music (soul) cannot be seen, but if the harp (body) is destroyed, music will no longer exist.

In response to the second definition, Shelly gave the example of radio waves. Radio waves cannot be directly detected by our five senses, but they can also be destroyed.

In response to the third definition, Shelly gave an example of the relationship between radio waves and radios. The radio waves (soul) appear because of the radio (body), and the radio just proves the existence of radio waves. Likewise, if the soul exists, it should be reflected in a physical entity, thus proving that it is not actually intangible. (If you hook a soul up to a body, you can tell the soul is there by what the body doing. But that means the soul is not really undetectable. But if the soul is not really undetectable, it not really invisible in the relevant sense.)

5. The argument from essential properties

Plato believes that life is a necessary attribute of the soul, so the soul is immortal , is indestructible. The soul has the ability to think and will always exist.

Shelly suggested that before discussing necessary attributes, one should understand the difference between necessary attributes (basic attributes) and accidental attributes.

Necessary attributes, also known as basic attributes, are attributes that an object must have and are closely related to its survival. Such as fire and heat.

Accidental property, its existence or absence does not directly affect the existence or absence of the object. For example, for a blue car, whether the car is blue or not does not affect the existence of the car.

Shelly said that in fact Plato has always acquiesced in the existence of the soul, and then discussed the issue of the immortality of the soul on this basis. But in fact, there is still a question mark as to whether the soul is an inevitable attribute of life. He asked some examples. Finally, he gave his view as a physicalist: the soul cannot prove its existence.

Course link: Yale University’s famous open course: Philosophy-Death Death Others