Some philosophical problems and puzzles

To give you a taste of philosophy, here are some philosophical problems for you to think about :

A Paradox about truth

A paradox arises when beginning with plausible assumptions, we derive a conclusion which is absurd or contradictory. Many simple concepts which we use in everyday life surprisingly lead to paradoxes. In trying to solve these paradoxes we hope to gain a better understanding of such concepts. One example is the Liar paradox which concerns our concept of truth. Consider the following sentence :
This sentence is not true

Is the sentence true or false? If it is true, then what the sentence says is true, so it is not true. But if it is not true, then should it not be true as well, since it says of itself that it is not true? So it seems that it is both true and false, but how can that be possible?

The Philosophy of mind


In this branch of philosophy we hope to understand better the different aspects of our mind, such as thinking and consciousness, and to find out the best scientific approach to study these phenomena. One issue concerns the nature of intelligence : what is it for something to be intelligent, and is it possible to construct an intelligent thinking machine? One suggestion is that something is intelligent if, and only if, it can pass the so-called imitation test. To pass the test, a machine must deceive a judge into thinking that it is human. The idea behind this proposal is that if something can fool us into thinking that it is human, then surely it is intelligent. Do you think this is a good test for intelligence? If something fails the test, must it be stupid? And can there be unintelligent machines that nonetheless pass the test?

Philosophy of Science


Here philosophers study the methods and concepts of science, as well as some basic problems in the particular sciences. These include issues like : What is a scientific explanation? What is the role of mathematics in science?

One topic in theoretical physics is time travel : does the structure of our universe allow us to travel back to the past, or forward to the future? Some people have argued however that the idea of backward time travel is incoherent. For what if you travel back to the past when you were a baby? If that were possible would there not be two of you at the same time?

Besides, what if you try to kill the baby that was you? Surely you will not succeed, since you did grow up and live until now. If you died when you were a baby, you could not have lived to do the time travel! So it seems that you must fail in your attempt to kill your earlier self. But it also seems to imply that however hard you try, you cannot kill the baby. Isn't this strange, and is it really possible?

Moral Philosophy


In moral philosophy we think about questions like : how should we live our lives, and are there objective moral principles? We often think that we should minimize suffering and bring about as much happiness as we can. On the other hand we think we should respect other people's rights. But how exactly do we balance these two concerns? Think about the following two cases :

  1. You are driving a train but you cannot stop it. There are five man further down the track and you know you will kill them if you do nothing, unless you turn the train to the right now. But there is one workman on the right and you will kill him instead if you turn the train. Should you?
  2. You are a doctor at a hospital and five patients will die if you do nothing. You can only save them if you kill a healthy and innocent person next door, and transplant his lungs, heart and kidneys to the five patients. Should you?

Perhaps you might want to answer "yes" in the case #1, and "no" in case #2. But can you justify your answers?