Can you tell good arguments from bad ones?

Can you tell good arguments from bad ones? (Series 2) Study each argument and try to decide if it is convincing (and if not, why). Then click the ‘page down’ key to read an assessment of the argument.

God is said to be both all-powerful and all-good. An all-good God would prevent evil if he could. And since God is supposed to be all-powerful, he could indeed prevent it. But evil exists. Therefore God does not exist.

This is actually a strong argument, though one can have doubts about some of the premises. For example, many Christians have in effect doubted the claim that an all-good God would prevent evil if he could, for they say that an all-good God would want to give humans the gift of free will, which can, despite God’s wishes, be used for evil.

Jesus was either right or wrong in thinking that he was God. If he was wrong, he must have been suffering from a serious delusion and thus mad. So anyone who denies that Jesus was God should think that he was mad.

This is a favourite argument of many Christians. It is meant to put the sceptic in an awkward position, by forcing him either to give up his scepticism or describe Jesus as mad, neither of which he would find congenial. Formally speaking, the argument is valid, but the premises are highly questionable. For one thing, it is not historically certain that Jesus did ever claim to be God – this may be something that later followers extrapolated form his life and words. But a more fundamental criticism is this. The word ‘mad’ is what is sometimes called a thick ethical term, which means that it combines purely descriptive elements (about behaving in certain ways) with certain attitudes (mainly pity or derision). It would be possible to apply the descriptive elements without having the associated attitudes. Normally, someone who claims such extraordinary things as his own identity to God would indeed be the object of such attitudes, but if the person has other qualities that are more praiseworthy and seem more important, we might feel differently towards him or her. Those sceptical of Jesus’ supernatural claims could plausibly maintain that this applies to him.

Human life begins at conception. Therefore, to kill a foetus is to kill a human being and is thus always murder.

One part of the conclusion follows from the premise, but not all of it. The part that does follow is the part that says that to kill a foetus is to kill a human being. This must indeed be true if human life begins at conception. But the further claim that it is also murder does not follow. A murder is not just a killing of a human being; it is the wrong or unjustified killing of a person. To show that the killing of a foetus is murder, you have to show, not only that it is the killing of a human being, but also that the human being is a person and that it would be wrong to kill this person. To show the former you have to show that the human being has the standard characteristics of a person, e.g. that it is capable of having wishes and beliefs. To show the latter, you need to show that there are no moral imperatives (such as saving the mother’s life) that would override the presumptive wrongness of killing this person.

An eminent philosopher once began a lecture with the following argument aiming to show that we are not identical with our bodies: A person cannot be identical with her body, since, when dead, her body does not have any of the characteristics of a person (e.g. the ability to have wishes and beliefs).

The argument tries to show that we, as persons, are distinct from our bodies. It does so by pointing out that dead bodies do not have the characteristics of persons. But this hardly proves the conclusion. Anyone who thought that persons were human bodies would claim that the identity obtains only for human bodies that are alive. (The suggestion would probably be that while you exist as a person, that person is a certain living body. When the body is dead, the person no longer exists.) Someone who offers this argument thus commits the fallacy of refuting a claim that is stronger than the one its opponent would maintain - and indeed absurd - namely, that every human body, dead as well as living, is a person.

We…cannot suppose that an individual’s thinking survives bodily death, since that destroys the organization of the brain, and dissipates the energy which utilized the brain tracks. (From Bertrand Russell, Why I am not a Christian)

Most philosophers would agree with this argument. But one question that could be posed is whether the argument takes account of the difference between causation and correlation. It might be suggested that the scientific facts only establish that as long as the brain is functioning, its activity is correlated with the person’s thinking. But this does not show that the brain activity is causally necessary for the thinking. Perhaps the thinking continues after death on the causal basis of something else – or even ‘free standing’. Improbable? Perhaps. But at first glance many of the findings of modern science itself (such as quantum indeterminacy) are equally hard to swallow.

A vicious criminal convicted of a serious assault has a religious conversion while in jail. As a result of this, his personality changes completely. All traces of aggression have gone, and he is now sensitive and amenable to reason. He is simply not the same person as the one who did the crime. Therefore it would be wrong to continue his punishment, and he should be released from jail immediately.

This argument raises questions about personal identity. If the basis of personal identity is psychological, as the argument assumes, then it is hard to avoid the conclusion that we are literally dealing with a different person and so not to release this person would be a case of unjustly punishing an innocent individual. But there are other views about personal identity. The most important of these is the view that personal identity is based on physical continuity. According to this view, the fact that we are dealing with the same individual in a physical sense guarantees that it is the same person, whatever his psychological characteristics. In that case, we would probably say that punishment is still warranted. The above analysis may, however, be too simplistic. We also need to consider the moral purpose of punishment. Some people think that punishment is primarily inflicted for the purpose of retribution, i.e., to rectify an injustice by treating the criminal in the same way as he treated his victim. Others (especially utilitarians) think it should aim at crime prevention, especially by deterring potential offenders. If you take the latter view, you are more likely to think that punishment is still warranted in this case, since even if we are not strictly dealing with the same person, there could still be a valuable deterrent effect.

There is enormous disagreement between individuals and between different cultures about what is or is not art. Tracy Emin thought her unmade bed was art. Others disagree. There are many other examples of variations in notions of art and beauty. For example, not every culture accepts, like ours, that beauty in women requires slimness. It follows that aesthetic notions (notions of art and beauty) are relative to cultures or even to specific individuals. There is no absolute standard here.

Although the fact of wide variation suggests that there maybe no absolute standards, the conclusion does not inevitably follow. Suppose you asked a large number of non-scientists to guess the weight of the Earth. You would get a very wide range of different answers, but it doesn’t follow that there is no right answer to the question of what the Earth weighs. On the other hand, aesthetic subjectivism (i.e. the view that there are no absolute standards in art) is quite a popular position, certainly more popular than ethical subjectivism. Can you think of a better argument to support it? You may not find it easy! Here’s another question (a more manageable one). Why do you think aesthetic subjectivism is more popular than ethical subjectivism?

In this argument, John Stuart Mill tries to show that each of us ought to aim at the ‘sum’ of human happiness: …each person’s happiness is a good to that person, and the general happiness, therefore, a good to the aggregate [totality] of all persons. J.S. Mill, Utilitarianism

John Stuart Mill was one of the great empiricist philosophers, and also a great advocate of social reform - he was one of the first people in Britain to advocate votes for women. But he must have been having an off-day when he wrote that. To see how bad the argument is compare it with this: Each of us wants our daily amount of fruit; therefore each of us wants everybody’s daily amount of fruit all put together. Mill’s argument is really no better than that.

Either Christianity is true or it is false, and you’ve no idea which. If you live the life of a Christian, then even if Christianity turns out to be false, you will not have done yourself any harm. And if it turns out to be true, you will have saved yourself from damnation. Therefore you ought to live the life of a Christian.

This is known as ‘Pascal’s Wager’, and, as you would expect, it is very controversial. One thing that should make you suspicious is the fact that you can produce an exactly parallel argument for any religion that has the following features: (a) It can plausibly be claimed that you don’t lose much by following its precepts; and (b) If the religion is true, you will receive a dreadful punishment if you do not follow it. In order to use the argument to support Christianity, as opposed to other religions satisfying these criteria, you would have to point to some special alleged property of the former, e.g., that it is intrinsically more probable than the rest. But that threatens to make Pascal’s argument redundant.

A God that exists is better than a God that is merely imaginary. But God is, by definition, a perfect being. So if God did not exist, he would not be perfect and so he would not be God. Therefore, God must exist.

This is a version of the so-called Ontological Argument for God’s existence, propounded by Descartes amongst others. The argument strikes most people as pretty suspicious, but what exactly is wrong with it? The mistake seems to be in thinking that defining something to have a certain property guarantees that it has that property. Admittedly, this does have a certain superficial appeal. A ‘bachelor’ is defined to be an unmarried man, so a bachelor must be unmarried. There is no room for dissent there. Or is there? Shouldn’t we rather infer that if there exists a bachelor, then he is unmarried—our common knowledge that there do exist bachelors in the real world may make us overlook the necessary qualification. This being so, all that the suggested definition of God allows us to conclude is that if God exists, then he exists—hardly an earth-shattering conclusion and certainly not what the argument was intended to prove.

We know the contents of our own minds directly. But as far as knowing other people’s minds is concerned, we are limited to what we can observe of their behaviour. It is therefore possible that there is really no consciousness at all ‘behind’ the behaviour, that other people are nothing but mindless ‘zombies’.

This is an example of one of the many forms of scepticism that philosophers have tried to grapple with. It is scepticism about the reality of ‘other minds’. Of course, this is not an argument that anyone would ever seriously put forward, as it is psychologically impossible to believe the conclusion. But some philosophers take it upon themselves to assess the argument anyway, to ask in effect, whether we are rational to reject it and if so, why. There is no agreed answer. But here is one thing to consider. What would it actually be like to think that other people were zombies? What exactly - in practical terms - would you have to think in order to think that? If you have difficulty answering this question, then you should suspect that the hypothesis isn’t even a meaningful one.

Everything that I experience is consistent with the hypothesis that I am really just a brain in a vat, being constantly supplied with virtual reality updates of an apparently real world by a computer (as in the movie Matrix). So perhaps this is the way things are!

Another sceptical argument. Not the kind of thing that would get anyone seriously worried perhaps, but the answer ought to tell us something important about the nature of knowledge or rational belief, one would think. Again, there is no agreement about the answer. But here is a question that seems worth raising: if it were true that we were just brains in a vat, would it really matter? As Pascal said, a peasant who dreams every night that he is a king is as happy as a king who dreams every night that he is a peasant. And could it even be that at some level there is no difference?

‘Goodness’ is indefinable. For suppose it could be defined. Let’s say, for example, that someone proposes this: ‘good’ = ‘likely to lead to happiness for oneself or others’. Someone could say ‘I agree that such-and-such is good, but I don’t agree that it is likely to lead to happiness for myself or others.’ Even if we could not endorse what she said, we would surely have to accept that she wasn’t contradicting herself. So the proposal would not be right as a definition. And similarly for any other proposed definition. Therefore, as asserted initially, goodness is indefinable.

This famous argument of G.E. Moore seems correct to me, but it is very controversial. See http://plato.stanford.edu/entries/moral-realism/

If time travel were possible, then a person could travel back in time and kill one her ancestors, which would prevent her own existence. But then if she does not exist, how can she have done the killing? This is a contradiction. So time travel is not possible.

This is a favourite science fiction scenario, but the conclusion – that time travel is not in fact possible – is rarely drawn by the authors and screenwriters who present it to us! In any case, there may be a reasoned way of avoiding that conclusion. One possibility is that when the time traveller kills her ancestor, she flips into an alternative world – it is then her former self in the ‘original’ world who ceases to exist, not her new self.

Can you tell good arguments from bad ones?