Is it, in general, better to take actions that could be described (variably, according to your moral temper) as sinful, or wrong, or regrettable, "in your stride", rather than feel guilt if it is the case that guilt will not diminish the probability of its happening again? Is guilt something irrational in the sense that we would really be better to (i) rid ourselves of it (ii) discourage aspects of the upbringing of children which conditions this response in them, so long as there are other ways to disincentivize harmful behaviour?

With respect to your own bad acts, isn't guilt often useful precisely because it can diminish the probability of you acting in that way in the future? So, I think the general answer is that you should take seriously the power of appropriate guilt. With respect to responding to bad actions performed by others, the best general answer is probably something uninteresting like "strive to respond to wrong in ways that are as rational and constructive as possible," and figuring out how to do that has everything to do with the specifics of the situations you confront. Douglas Walton's work on critical thinking is useful here, I think -- he adopts an interesting dialogical approach that focuses on understand the exact "contexts of dialgoue" of the most challenging and important situations we face and then provides concepts and tools that help make it easier to understand exactly what you need to do to respond to challenges in a a rational, constructive manner. (I especially like Walton's survey text, ...

Will good things happen to a person if they do good? Does karma exist? So in other words: If one share with the world everything they have without expecting good to happen to them in return, will great things happen for them anyways?

Surely not every good action will be recognized or rewarded by others, but most people would benefit from living in a world where many people perform good acts and so contributing to the existence of such a world might be a good goal to strive toward even if you are moved neither by a desire to improve your own soul (as Plato might have it) nor by the prospect of doing good out of a sense of duty and respect for morality and rationality (as Kant might have it).

Even though it has been strongly argued that divine foreknowledge doesn't negate free will, allow me to ask the question another way. How could God know our decisions if they are truly free? To know the outcome of something is to imply contingency (and determinism). To put it another way, if a third party can know the nature of an individual then that individual cannot be the author of his nature.

The compatibility or incompatibility of divine omniscience and mortal freedom interests me a lot, although the concept of the "author of one's own nature" strikes me as relatively unclear and probably not that useful for investigating this. Sean sketches out one answer that may be satisfactory to those who believe that free will is compatible with all of one's choices being determined by preceding events. I'm not sympathetic toward this sort of "compatibilism," and I've never been persuaded by any argument that free will could exist a world where there could be an omniscient God. So, my short answer to your question is that I think that omniscience does negate free will. (My own position is an unpopular one, and as Sean suggests a lot depends on exactly how you define the key terms used in the original question and in the answer that I just gave....)

How can an object or thing that is not physical (like the mind or the soul) be located in space? Is it actually located in space? If it is not, then where is it located?

An interesting question, and one that is important to those substnace dualists (i.e., those who believe there exist both material and immaterial substances) want to explain how immaterial souls can act on material bodies and how material bodies can act on immaterial souls. Here's one answer from the history of early modern philosophy: The eighteenth century German philosopher Immanuel Kant believed that impenetrability is the crucial concept for understanding spatial location: a substance is located in that region of space that it "fills" or "occupies" by exerting a repulsive force against other substances in space; a substance is located in that volume of space from which it repulses other substances (i.e., which other substances cannot penetrate). The early Kant was a substance dualist who believed that there were spiritual substances that possessed a repulsive force and occupied space in just this way. (A major difficulty with this answer is that it is difficult to understand why...

Why do people (especially philosophers) engage in arguments which cannot be resolved?

I would add that studying philosophical issues--reading about them, discussing them with others, and writing about them inside or outside a class--can not only be intellectually edifying, but pratically useful as well: this is an an excellent way to hone one's critical reading, writing, thinking, and oral communication skills that are useful in many professional and personal contexts.

What books are most important for a neophyte philosopher to read?

I second Catherine's suggestion: At best, an introductory text will provide you with the opportunity to read a few excerpts of philosophical writing, and at worst the text will be dominated by boring summary. Based on my experience reading and teaching them, it is likely that reading texts like these won't inspire or engage you at all. Exactly which texts might engage and inspire you depends a lot on your interests and preferences. (For me, it was reading Hobbes' Leviathan; I still remember exactly where I was when I really engaged with that text for the first time! Quite of a few of my students in introductory classes have engaged well with Descartes' Meditations and Plato's Republic .) So, as the other panelists have suggested you should "shop around" until you find a text that seems interesting enough for you to read with great care -- that's the best way to learn how to read philosophy.

What exactly is the moral/ethical problem with a professional athlete taking performance enhancing drugs? I'm talking about a talented professional who carefully weighs the known risks and side effects of such drugs and decides their use is necessary for him/her in order to be competitive in their sport. Shouldn't this just be a personal decision? Aspiring beauty queens are allowed to get plastic surgery, and athletes are allowed to get "corrective" laser eye surgery (significantly improving their perfectly normal distance vision)...

I agree with Aaron that a central reason why taking performance enhancing drugs is wrong is that this action violates existing rules and so undermines standards of fairness that are so important to sport and to the enjoyment of sport by others. With respect to the content of these rules, I imagine that an historian of sports would have an interesting story to tell about the differing conceptions of competition that have been in place at various times and places, and I would bet that "fair sport" in the past has encompassed a variety of personal risks by athletes and many approaches for maximizing athletic skill and achievement. One could certainly imagine ethical defenses of rules and practices that admit more risk than our current rules--reducing harm is an ethical basis for those rules, but need not be the only basis for constructing rules about sport.

Why is Utilitarianism rubbish? We are supposed to do an action which will create a net increase of welfare - how are we to judge if a particular action will increase welfare? If we are forced to make this decision, do we not have to rely on some 'internal moral' or integrities that we might hold, therefore making it quite impossible to judge correctly what will increase the general happiness? And doesn't utilitarianism require us to act as machines, not bothering about what we feel?

The the idea of caring about others' welfare is not rubbish, and reflecting on the consequences of our actions and thinking hard about ways that I can benefit connects to some of my deeply-held feelings about how I want to behave. I think it is also too strong to say that utilitarianism is rubbish as an ethical theory: we can learn a lot by exploring and assessing theories that address crucual issues even in a flawed way. That said, utilitarianism is severely flawed. I think the most important problems include the difficulty of defining welfare, of measuring it, and of making accurate and specific predictions about the consequences of our behavior. Other panelists can say much more, I'm sure, but in my opinion no satisfactory resolution to these problems is in sight.

Critical thinking: We are bombarded with information all the time so I think it's very important to use "critical thinking" but it's not easy. So my question is: what are the basics in critical thinking?

I think it is also useful to think about the separate skills that are necessary for applying the concepts and techniques that Joseph described to complex real-life situations. Alas, we often have the most need for critical thinking when confronting the situations where this is the hardest to do: situations that are really complex, that matter a lot to our lives, which involve complex emotional dynamics or serious interpersonal conflict, and so on. So, to best use critical thinking in our own lives we need to be able to handle "messy" situations like those. For example, it is useful to understand your own and others' agendas and motivations, the emotional dynamics of a situation, how to act in ways that have the best chance of making a difficult discussion more rational and more constructive. When I teach critical thinking, I prefer to teach the reasoning skills that Joseph describes together with serious reflection on the "messy real life" issues that I sketch out above. The best critical...

Do philosophers really think that the problems they discuss are important in themselves, or does thinking about the problems merely serve as practice in analytical thinking? How does philosophy differ from puzzle solving (besides the fact that puzzles actually tend to get solved)?

As Richard states, there is considerable disagreement among philosophers about which philosophical questions are significant, and why. There is also considerable truth in your suggestion that studying the methods and texts of philosophy is itself a valuable way to develop one's analytical reading, writing, thinking, and communication skills. So, as a teacher of philosophy I hope that my students will both gain useful insight by studying diverse philosophical questions and approaches and will also gain useful analytical skills. This is an extremely powerful combination, and this power is one reason why philosophy students tend to do so well in the professional job market and also tend to advance quickly within their chosen professions. About puzzle solving: the difference that you touch on, that philosophical puzzles are rarely solved in definitive way that gain professional consensus, is the central one. I take this to mean that investigating a philosophical question is very different from...