What is the importance to appealing to an audiences pathos, logos, and ethos ("the ingredients of persuasion) when writing or speaking?
Empathy. To appeal to one's emotion (pathos), logic (logos), and ethics (ethos) it to connect with them. When the audience feels a connection, their attention and appreciation is greatly increased.
If you and four other people were on a sinking raft in the middle of the ocean that could only hold a total of four people, should you push one person (likely the weakest) off in order to survive, or allow all of you to die in order to not have blood on your hands?
There is no wrong or right answer. There are only different perspectives. Utilitarianism is a philosophy that justifies doing something that may be perceived as immoral for the greater good. The opposite philosophy, Kantianism, believes that there is a "supreme principle of morality" and cannot justify doing anything immoral, such as sacrificing one person on the raft in order to four others (after all, you are still responsible for the death of one person).
Why did the dog of psychologist, Pavlov, salivate every time he rang a bell?
Every time the bell was rung, the dog would be fed. After this happened several times over, the dog expected the food once the bell rang, and therefore salivated just my the sound of the bell. This process is known as "classical conditioning."