http://www.debate.org/debates/All-Morality-is-Relative/1/
I, of course, being a Christian apologist, defended moral realism. Here is my opening statement in the debate:
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Thanks to Pro for initiating the debate, and thanks to the reader for carefully considering our arguements.
Preliminaries
Pro did not stipulate the burden of proof in the first round, but I'm going to assume a shared burden of proof which means we each have to defend a point of view, and not merely refute each other's argument. Pro has to show that morals are relative, and I have to show that morals are objective.
Since we each have a point of view to argue for, and since Pro used this round to argue for his point of view, I'm going to use this round to defend my point of view. Then I'll use the next round to give a rebuttal to what Pro said in this round, and he can use the last round to rebut what I say in this round. That way we each have an equal amount of space to defend our views and offer rebuttals.
A note on epistemology
There are two kinds of knowledge: a priori and a posteriori. A posteriori knowledge is knowledge we infer from prior items of knowledge. A priori knowledge is knowledge that is not inferred from prior items of knowledge. Since for whatever items of knowledge we might have, it was either inferred from prior knowledge or it was not (by the law of excluded middle), these two types of knowledge exhaust the possibilities.
It is not possible for all of our knowledge to be a posteriori because if every item of knowledge is based on a prior item of knowledge, that leads to an infinite regress. It would be impossible to arrive at any item of knowledge since there would be no starting place.
So if knowledge is possible at all, then there must be a priori knowledge. Since there is knowledge that is not based on anything prior, the knowledge must be obtained immediately upon reflection. That is, rather than derive the knowledge by reasoning from prior items of knowledge, we have the knowledge immediately just by reflecting on it.
A priori knowledge
There are some items of knowledge we have that could not be based on anything prior since they are unprovable. Those items of knowledge must be a priori. Our a priori knowledge can be subdivided into three categories according to what they have in common and how they differ.
1. First person knowledge
These are items of knowledge about our own first person awareness. Some examples include the fact that we're thinking, perceiving, remembering, and feeling, and what we're thinking, perceiving, remembering, and feeling). This is where Descartes' famous cogito belongs. Merely by thinking, we can know that we exist.
2. Rationally grasped knowledge
These are things we can know about the world outside of our own minds, but they are still known immediately upon reflecting on them. Examples include the law of non-contradiction, that 2 + 2 = 4, and that when two straight lines intersect, the opposite angles are equal. Some of the items in this category require a little more careful reflection to see than other items; consequently, not everybody is able to see them as clearly. For example, one can carefully reflect on a triangle and discover that it's interior angels must equal 180º without having to measure them. But not everybody has the brain power to see that, and they have to either take the textbook's word for it, or measure the angles.
3. Synthetic a priori knowledge.
These are items of knowledge that are built into every healthy and normally functioning mind. Examples include the fact that our senses are giving us true information about the world (which is how we know the external world exists), that our memories are giving us true information about the past (which is how we know there's a past, and how it's possible to have a conversation), and that the observed can be extrapolated to the unobserved (which his how we're able to learn from experience, make predictions about the future, arrive at probabilities, and engage in the scientific enterprise).
What all of these categories have in common is that none of the items in them need to be proved before we can know them. in fact, in most cases, it's impossible to prove them. But without them, it would be impossible to prove anything else. The items in the first category are incorrigible because of our immediate access to our own mental states. The items in the second category can be known with certainty because they express necessary truths, and the necessity of them can be rationally grasped. Once the items in the first and second category are seen clearly with the mind, it is impossible to be mistaken about them.
The items in the third category differ from the first two in the fact that it's possible to be mistaken about them. They do not express necessary truths. It's at least possible that the external world is an illusion. It's possible that there was no past. It's possible that while past experiments have always indicated the world works in a certain way, it may work differently tomorrow. In fact, we sometimes make mistakes regarding the third category. We mistake hallucination with external reality. We remember things incorrectly. We make hasty generalizations. But the fact that we sometimes make mistakes regarding the third category doesn't shake our belief in the general principles.
The third category of knowledge has these things in common:
1. None of them can be proved.
2. It's possible to be mistaken about each of them.
3. We sometimes make mistakes when applying each of them.
4. All mentally healthy people apprehend them.
5. It seems prima face unreasonable to deny them.
6. Even people who do deny them continue to perceive them as if they were real; they merely deny their reality.
7. We all use them in our daily lives.
I would like to be able to give a longer list of items of knowledge for the third category and show how each of them fit all seven of those features, but space is limited.
Moral realism
My argument for morality is that morality fits in the third category because all seven of those traits apply to our moral awareness. We can get rid of morality by denying this particular way of knowing, but in doing so, we will undermined the justification we have for believing in every other item of knowledge in the third category since they are all known in the same way. Since morality has all these things in common with every other item in the third category, morality is on equal epistemological footing. That means it's just as rational to believe in morality as it is to believe in the past, the external world, the uniformity of nature, etc.
Now, let me show how morality fits all seven of the above features.
1. Pro probably already agrees with me that morality cannot be proved.
2. Pro probably also agrees with me that we can be mistaken about morality. In fact, he thinks we are.
3. We sometimes make mistakes in our moral reasoning. This is evident in the fact that people sometimes come to different moral conclusions even when reasoning from the same moral premises.
4. All mentally healthy people perceive a difference between right and wrong. This is evident in the fact that we consider sociopathy to be a mental illness. With the exception of sociopaths, the fact that we all perceive a difference between right and wrong is evident in the fact that (i) we all judge others, which entails applying standards of behavior we think actually apply to other people and not just ourselves, (ii) when accused of wrong-doing, our first instinct is not to deny the standard, but to make excuses for why we didn't violate the standard, (iii) moral decision-making is difficult because we think there are actually correct and incorrect answers to moral questions, (iv) moral relativists are rarely consistent, and (v) we all find moral relativism to be counter-intuitive when we think about specific instances of egregious moral wrongs.
5. It seems prima facie unreasonable to deny morality. The denial of morality leads to many counter-intuitive results. It would follow that no culture is better or worse than another. There's no such thing as moral improvement. There are no unjust laws. There is no objective basis upon which to criticize other people. Nobody deserves praise or blame. Debates on moral issues are just as meaningless as debates on whether salmon tastes good since morality would reduce to preference.
6. Even people who deny morality continue to perceive a difference between right and wrong. They just deny that the perception corresponds to anything outside of their heads. Instead of saying, "Rape is really and objectively wrong," they say, "Rape is wrong for me," or, "I personally oppose rape." But rape continues to be abhorrent to them, and they find it difficult to deny that it really is wrong since it appears wrong to them.
7. Every one of us thinks morally in our day to day interactions with people. Most of the time, we don't notice because the right thing to do is obvious and we do it without much thought. We know we shouldn't steal somebody's wallet, not just because we might get caught, but because it's wrong. We're polite to people, not just because we want them to be polite to us, but because we think that's the right thing to do. Whenever we face moral dilemmas, and it isn't obvious what we should do, then we're forced to think more carefully about morals. We do it continuously throughout the day, but especially when interacting with people.
Conclusion
Since morality fits the seven traits of the third category of a priori knowledge, it follows that morality is just as epistemologically warranted as the other items in that category. If we are justified in believing in the past, the external world, and the uniformity of nature, then we are equally justified in believing in morality. We can deny morality, but that would be just as unreasonable as denying the external world, the past, and the uniformity of nature. So the conclusion that any rational person ought to come to is that there really is a difference between right and wrong that is not merely just in our heads.