Making sense of God by Timothy Keller

Making sense of God by Timothy Keller

Timothy Keller’s The Reason for God, published a few years ago, was an excellent exposition of reasons to believe in God and Christianity.  Now Keller has followed up with what could be called a prequel, Making Sense of God, addressing those sceptics who see Christianity as so implausible that no rational person could even consider it. His aim is to show that Christianity is worth investigating.

Keller’s approach is to firstly compare the foundations of Christianity and secularism – the latter being the view that denies the existence of a supernatural realm and is concerned with the here-and-now. He begins by challenging the idea that religious belief is inevitably declining, citing statistics that show Christianity is thriving in the non-Western world. Many people sense that secular reason does not provide a sound basis for meaning and virtue, and fails to explain the widespread perception that there is more to life than just the material.

Keller goes on to expose the flaws in the narrative that claims the religious live by blind faith, while non-believers ground their position in evidence and reason. All reason depends on faith in our cognitive faculties, and the belief that science is the only arbiter of truth is itself not a scientific belief. No-one can “assume an objective, belief-free, pure openness to objective evidence”. Instead, we all operate based on a set of tacit assumptions about reality that we are not consciously aware of. In fact, secular humanism’s values can be traced back to its Jewish and Christian roots.

This means that instead of asking religious people to prove their beliefs, we need to compare religious and secular beliefs based on their evidence, consistency, and success in accounting for our experiences. Keller spends the majority of the remainder of the book performing this comparison.

Firstly, Keller notes the disdain postmodern culture treats having meaning in life. In an indifferent universe, the only meaning is that which we make ourselves. These created meanings can serve us well, and we must not tell secular friends their lives have no meaning. But he points out that created meanings are ultimately insignificant when the big picture is considered, and are impotent in the face of personal suffering. By contrast, Christianity claims there is objective, eternal Meaning that can be discovered, and teaches that suffering is a terrible reality that can still have purpose.

Meaning is linked to happiness and satisfaction in life, Keller’s next point of comparison. Despite the advances we’ve made in science, technology and medicine, we are not any happier. The ephemeral nature of satisfaction and our desire for something that the world cannot supply points to our being “made for another world” as C.S. Lewis famously put it. Keller draws on Augustine’s insight that dissatisfaction and discontentment is a consequence of our failure to love God first and foremost. If we love anything more than God, it will become the source of our happiness, and will eventually fail us.

People have always valued freedom, but in secular societies freedom has become the ultimate good. Freedom is now understood as the “right of the individual to choose his or her values”, and we can live as we see fit. Keller rightly notes that a focus on individual freedom has in many instances led to a fairer society, but thinks the narrative has gone awry. It has produced the “harm principle”, where we believe we should be free to live as we please as long as we don’t harm anyone else. But this is disingenuous, because the notion of harm is dependent on what a good human life consists of – and that is a matter of our subjective beliefs.

Also, an extreme focus on individual freedom and personal fulfilment actually threatens freedom itself, as self-absorbed individuals undermine communities and democratic institutions. According to Robert Belah, “the health of a society depends on voluntarily unselfish behavior” which involves infringing on our personal freedom. Paradoxically, we also find most happiness in our relationships, where we sacrifice our freedoms for the other. So absolute freedom is not an end in itself, but rather a means to an end. But what is that end? Keller has already explained the issues with deriving meaning and satisfaction from created things. If we consider that we are created by God, then God has determined our purpose and the constraints we should live by. And as in all relationships, both parties sacrifice their freedoms, God having done so by Jesus Christ becoming mortal and dying for us.

In chapter six, Keller moves on to our personal identity, noting the differences between the traditional concept of the self being “defined and shaped by both internal desires and external social roles and ties” and our modern, Western identity based on individualism and detachment. Like the focus on individual freedom, this has enabled considerable good, such as preparing American culture for the civil rights movement. But modern identity is also problematic. Our desires are constantly changing and often contradictory, and we can’t base our sense of who we are on them. We have to filter our desires based on a set of beliefs and values, and they are obtained (mostly unconsciously) from our culture and community. Unfortunately, modern society “adulates winners and despises losers, showing contempt for weakness”, and this makes our self-worth a fragile thing. Even if we eschew material success and base our identity on the love of another, if this is lost we will be devastated.

By contrast the Christian approach to identity is based on unconditional acceptance by God. Our worth is based on the value God has placed on us, not on achievements, race or relationships – or even our efforts to be moral. But this requires humility, and includes giving up our rights to our freedoms. Keller claims that a consequence of this acceptance is the ability to freely enjoy other identity factors such as race, work, family and community ties, and this is why Christianity is by far the most culturally diverse of all religions. He offers the example of African identity, the core of which is a belief that the world is full of evil and good spirits. Secularism rejects such beliefs, while Christianity accepts this understanding of the world, and offers a solution to the problem of how one can be protected from evil spirits.

Traditionally secularism has believed in the idea of progress, but optimism is beginning to crumble in the light of issues such as climate change.But humans are future-focused, and we need hope. But where can we find it? On the individual level, death is the end of all hope. If human relationships are what makes our life meaningful , death destroys them. But this is the message of Christianity – that there is hope beyond death, that love will survive. This hope is based in the reality of the resurrection of Jesus, who has defeated death for us.

Finally, Keller examines the problem of moral obligation. Secularism struggles to give an account of moral facts or even what comprises “good”, despite secularists having strong moral opinions. In what is probably his strongest chapter, Keller introduces the moral argument for God’s existence, noting that it has influenced many sceptical friends. He notes that human rights are far from self-evident, and that Christianity offers the strongest foundation for them.

Keller then goes on to ask which of secularism or religion provides the better foundation for human rights. Secularism’s best case is that they are self-evident, while Christianity claims our worth is based on our having God’s image within us, giving every human being dignity no matter what their capacity.When it comes to justice, secularism struggles without universal, objective values that religion can provide. Yes, there is the danger of becoming the oppressors when confronting oppression, and Christianity has often done so, but this has always contradicted the gospel.

In his final chapters, Keller reviews his comparison of secularism and Christianity, and concludes that Christianity offers a far superior narrative. In terms of key facets of human life, meaning, satisfaction, freedom, identity, hope and justice, Christianity makes sense. It is worth considering. But is it true? To answer that question, Keller offers a concise summary of the arguments presented in The Reason for God. He concludes with Langdon Gilkey’s powerful story of selfishness in a Second World War prison camp, where rationality proved insufficient as a basis for moral obligation when resources were scarce. Instead, people saw no reason to be unselfish, and it was the rare person who could self-sacrifice. Gilkey concluded that only faith in God, exemplified by former Olympic athlete Eric Liddell who was interred in the camp, enabled people to be truly unselfish in such circumstances.

Will Making Sense of God convince secularists to take a deeper look at the arguments for Christianity?  If they are willing to put serious effort into their reading of Keller, it certainly should. It does a thorough job of exposing the assumptions secularism makes about reality, which should make anyone demanding “evidence” for the existence of God a little more cautious in their assertions. Keller’s comparison of secularism and Christianity  is thorough and well-researched, drawing on broad range of scholarly sources. Charles Taylor’s A Secular Age is a key reference, and for readers unfamiliar with this work, it would be worth reading James K. A . Smith’s How (Not) to Be Secular: Reading Charles Taylor.

Making Sense of God is not an easy read. Keller covers a lot of ground, and references many philosophical concepts that some readers may not be familiar with. Secularists will find it challenging to their worldview, while Christians will find it intensely rewarding.

Timothy Keller discusses Making Sense of God in a Mere Fidelity podcast here


What is bigotry, really?

What is bigotry, really?

Recently, I was discussing Christianity with an atheist online, and homosexuality was raised (not by me). The traditional Christian view that homosexual activity is wrong was called a “horrible and oppressive teaching”, and I was labelled a bigot for holding this view.

No-one likes being called a bigot, including me (which is why some people use it as a debating tool), and I spent some time discussing their reasons in detail. In the process, I gradually began to build a picture of what they meant by the term.

Bigotry: the Internet definition

The first point made was that bigotry was when we didn’t treat people with respect. Apparently, “saying that someone’s sexual orientation is sinful or wrong is not treating people with dignity or respect”. I hadn’t actually said this, as I don’t believe an orientation is sinful, but rather certain behaviour. But it is fair to say that the traditional Christian view is that a homosexual orientation is not what God intended, and obviously behaviour is closely related to orientation.

Can you treat someone with dignity and respect without agreeing with or condoning their behaviour or sexual orientation? It seems obvious that this is possible. We can treat political opponents with respect despite strong disagreement. We can even treat criminals with dignity and respect despite their behaviour or their propensity to commit crimes. So we can criticise behaviour we disagree with without violating a person’s dignity.

The next claim was that “you’re only a bigot if your discrimination is based on certain categories, namely, categories about WHAT a person is”. This sounds reasonable, until the different possible categories a person can be classified as are explored. Then it gets problematic. Do we condemn the behaviour of those sexually involved with their siblings or parents? It quickly becomes apparent that what a person is does not seem to excuse certain behaviours such as incest.

When I pointed this out, they shifted their ground somewhat to claim that opposing incest was not bigotry because “the REASON for discriminating is the mitigation of harm”. So apparently the reasons for calling behaviour wrong are important, and if the behaviour leads to harm then calling it wrong is acceptable. Harm continued to be a key part of the argument, as they went on to say that “I have the right to force you to not harm gay people by not allowing them to marry. You do not have the right to harm gay people who want to marry, since that action has no tangible negative consequences”.

Basing an argument on harm is risky, of course. Since SSM is a relatively new phenomenon, we don’t know what harm might result to individuals or society in the future. Perhaps little or none. Perhaps harm might even be somewhat subjective when it comes to societal harm. But to assume that SSM has no “tangible negative consequences” is premature.

As Christians, we also must be wary of basing our arguments on harm. If we hold to the traditional Christian position of marriage as designed by God and between a man and a woman, we believe that ultimately this definition of marriage is good for the world. Conversely, we believe redefining marriage will prove harmful. But believing this does not mean it can be empirically demonstrated. Eventual harm may be many years in the future, or even unquantifiable. It might be that in the short-term, some research might indicate there are benefits to SSM. So it is unwise to base our argument on evidence of harm.

Bigotry: the dictionary definition

Rather than rely on the dubious musings of an Internet atheist determined to prove a point, I decided to examine the dictionary definition of bigotry.

The Oxford dictionary defines bigotry as “intolerance towards those who hold different opinions from oneself”. Ironically, that describes my opponent rather well, but it is premature to call them a bigot.

The Cambridge dictionary’s definition is “a person who has strong, unreasonable beliefs and who does not like other people who have different beliefs or a different way of life”. Merriam-Webster defines a bigot as “a person who strongly and unfairly dislikes other people, ideas, etc. : a bigoted person; especially: a person who hates or refuses to accept the members of a particular group (such as a racial or religious group)”.

These latter two definitions seem to capture an important point – bigotry is about dislike or hatred for those who hold different beliefs or different ways of life. Bigots hate, and hatred is wrong.

But is disagreement or disapproval about behaviour, opinions or lifestyle bigotry? No, not if no hatred accompanies these views. Of course, sometimes hatred does come with these views, and that is bigotry. But disapproval of behaviour doesn’t require hatred – ask any parent.

Philosopher Ed Feser makes this point stating that “disapproval of homosexual acts simply does not entail hatred of homosexuals themselves, any more than a vegetarian’s or vegan’s disapproval of eating meat entails hatred of meat-eaters”.

Redefining bigotry

Nonetheless, it is common to attempt to redefine bigotry as disapproval or disagreement on issues such as SSM that are supposedly “settled”.

This is a strategy whose aim is to shut down opponents and win debates, and it is an effective one. For example, Mark Joseph Stern states that a bigot is “anybody who opposes equal rights for gay people“, which implies anyone opposing SSM. Opposing views are automatically labelled as bigotry, and no further discussion is possible. What is there to discuss with a bigot?

The philosophical community has also moved in this direction, with many philosophers considering that the SSM debate is over, and discussion is no longer required or even legitimate. Christian philosopher Richard Swinburne felt the wrath of this view recently when he was invited to present a lecture on sexual morality at the Society of Christian Philosophers (SCP) meeting. His view that homosexual acts are immoral and that homosexuality is a disability that should be cured are widely known, and he was predictably criticised. However the President of the SCP felt compelled to apologise for “the hurt caused” by his lecture, despite Swinburne’s position being a commonly held view amongst Christian philosophers (and others) throughout history.

Feser’s discussion of this incident is instructive, particularly on the issue of hurtfulness. He points out that philosophers discuss all sorts of ideas that can cause offense, but that is no reason to end the discussion. Abortion is a prime example, where arguing that abortion is murder is likely to offend women who have had abortions – and yet it is very much a live topic in ethics. Citing hurt feelings should not be used as a tactic to shut down debate.

The question then is at what point is an argument “settled”? At what point should debate largely cease, and it be acknowledged that further argument is unproductive? There seems to be no easy way to determine this, but there is still widespread disagreement about SSM. We don’t seem to be at the point where we can declare it settled – except in the minds of those who want to declare victory for their view.

Christian hypocrisy

It is all very well to conclude that disapproving of certain behaviours is not bigotry, but the commonly cited adage of “hate the sin, love the sinner” seems trite given the apparent hate for gay people that some Christians have demonstrated. Often we have been and are bigoted, and the church has serious work to do in repairing relationships with the gay community.

We have also been hypocritical in condemning gay sex but tacitly or even blatantly condoning other damaging behaviour in our churches. As John Stonestreet and Sean McDowell note “it’s not lost on the gay community that the church held no (or at least very few) marches or rallies against no-fault divorce, adultery, or other things that have done even greater harm to marriage and families. There is a reason that the gay community feels singled out. Though we are often unfairly accused of bigotry and hate, we have been inconsistent”. I would add that at times we have been fairly accused of bigotry and hate.


Charles Taylor, in his opus A Secular Age, describes our current age as one of “expressive individualism”, and the prime value is personal choice, irrespective of the choices made. Consequently, the only virtue is tolerance of people’s choices, and “the.sin which is not tolerated is intolerance”. The result is the abuse of those who make the judgement that some behavioural choices are morally wrong.

Real bigotry, however,  involves hatred for others, not disagreement on controversial issues. Redefining bigotry to denigrate those who hold that certain behaviours are wrong is an attempt to shame and bully opponents into silence or reluctant agreement.

Christians are not bigoted in regarding homosexual behaviour as immoral, provided they are not disliking or hating those whose behaviour they are criticising.

A caution though: we need to carefully examine our hearts to discern whether we are truly loving those who we disagree with, and whether we are disproportionately highlighting one sin and treating it as somehow worse than others.






Are there objective moral values?

Are there objective moral values?

Objective moral values are moral values that are “independent of human desires, perceptions, beliefs and practices”. Those who hold that moral values are objective are known as moral realists, and they believe that statements such as “slavery is wrong” are true or false regardless of who says them, and where and when they were said.

Atheists such as Nietzsche, Hume and Mackie all agreed that there are no objective moral values in a godless universe. Although this is a common position, not all atheists hold to it, and a recent post concluded that it is possible to maintain that objective moral values could exist without God. This involves accepting that brute moral facts just happen to exist in our universe, and that they match our moral beliefs.

By contrast, theists explain moral facts by appealing to the necessary existence of God, which neatly explains moral obligation and why moral facts are correlated with our moral beliefs. The theistic view seems more persuasive, but of course the theistic worldview entails many other commitments which atheists find untenable.

Why do atheists like Wielenberg even think objective moral values exist? Given their commitment to an evolutionary account for our existence, it seems logical to attribute our moral beliefs and our intuitions about these beliefs to natural selection, at least indirectly. But doing so makes it difficult to be a realist about moral values, as it leads to Sharon Street’s “Darwinian dilemma” – either evolutionary forces have somehow conspired to produce moral beliefs that match these objective moral values, or our moral beliefs don’t coincide with whatever objective moral values exist at all. If objective moral values are jettisoned, the Darwinian dilemma dissolves, so why hold to this position?

Interestingly, it’s a very common position. In fact the majority of philosophers surveyed  are moral realists. Given that over two thirds have a preference for atheism, it seems moral realism is widespread even amongst atheists.


David Enoch contends that believing morality is objective has considerable appeal to us, and he gives three reasons why this is so.

Firstly, Enoch uses a joke to illustrate what he calls the spinach test. A child who hates spinach says “I’m glad I hate spinach, because otherwise I might have eaten it, and it’s yucky!”.  It’s funny because the only reason for not eating it is because of personal preference. If you did like it, it wouldn’t be yucky.

But it isn’t funny when it’s about a moral position. It seems quite reasonable to say, “I’m glad I wasn’t born in an era when slavery was acceptable, because I would have accepted it, and I think slavery is wrong”. This sentiment seems reasonable because we are thinking beyond our personal preferences. We think slavery is objectively wrong.

Enoch’s second test is about how moral disagreement feels – the phenomenology of disagreement. When we have an argument about a topic such as abortion, or some other issue we care deeply about, it doesn’t feel like an argument about personal preferences  such as the taste of chocolate.  It feels like an argument about something objective. Enoch compares it to a debate on global warming, which we know to be an objective matter irrespective of our position on it.

The third test is the “what if?” – or counterfactual – test for objectivity. If our beliefs or practices were very different, would it still be true that so-and-so? Enoch gives the example of smoking causing cancer. If we believed smoking was harmless, would it still be true that smoking causes cancer? Of course – it is an objective fact that smoking causes cancer, no matter what we believe. We can apply the same test to moral beliefs. If  we believed slavery is acceptable, would it still be wrong? It seems clear that the answer is yes, slavery would still be wrong. We would want a society that believes slavery is acceptable to change their views.

Enoch contends that these tests demonstrate that we very much want to regard morality as being objective. We want to be able to say that torturing babies for fun is objectively wrong no matter what some people may think.

But we are still left with the Darwinian dilemma and consequently have at least one good reason to think that morality is not objective. Of course, some sort of theistic evolution can counter this, but are there any good arguments for objective morality other than our intuitions?

Yes, and they will be explored in part two, coming soon!

Can objective moral values exist without God?

Can objective moral values exist without God?

In a recent post it was argued that to have objective meaning in life, it is sufficient that there be intrinsically good activities we can pursue. Naturally, for theists the question arises, how can there be intrinsically good things without God? Doesn’t the very concept of goodness require grounding in God?

Most Christians would say yes, we can’t make sense of goodness, or indeed any objective moral values* without God. Even many atheists are happy to concede that moral realism (as it is known) seems to require a transcendent source. Moore’s Open Question Argument showed that moral properties could not be natural properties, leading atheists to deny moral properties exist. For example, Mackie states that “moral properties constitute so odd a cluster of qualities and relations that they are most unlikely to have arisen in the ordinary course of events, without an all-powerful god to create them”. As an atheist, Mackie concludes that there are no objective moral values .

In recent years, though, some philosophers have put forward non-natural, non-theistic versions of moral realism. For example, Erik J. Wielenberg believes that some ethical truths are necessary truths, that they are “fundamental features of the universe that ground other truths”. According to Wielenberg, some ethical truths don’t need to be grounded in God. They are simply brute facts – facts without explanation – that we have to accept. As non-natural facts, they are sui generis, in a class of their own.

Surprisingly, this view also finds some support from theists. For example, philosopher Richard Swinburne states that “fundamental moral principles must be (logically) necessary”. William Lane Craig concurs: “I agree wholeheartedly with Swinburne that some moral truths are necessary truths”.

Craig’s statement is initially puzzling, given that he is the champion of the moral argument that has as its basis the premise that if God does not exist, objective moral values do not exist. But how can this be the case if there are necessary moral truths? Surely necessary moral truths are not dependent on the existence of God?

Craig’s position is that necessary truths still require an explanation. He quotes Shelly Kagan’s The Limits of Morality: “unless we have a coherent explanation of our moral principles, we don’t have a satisfactory ground for believing them to be true”. So Craig is arguing that Wielenberg needs to explain why there are some necessary ethical truths. Without such an explanation, we have no reason to believe these truths.

In effect, Craig’s argument is that while there are necessary ethical truths, there are no necessary ethical truths that have no explanation, i.e. brute facts.

This is redolent of the Principle of Sufficient Reason (PSR), which states that for every fact F, there must be an explanation why F is the case.

There are two issues for Craig, though, regarding the PSR. The first is that the PSR is usually restricted to contingent truths, not necessary truths. Contingent truths are those truths that could have been false. If the PSR does not apply to necessary truths, then we can’t insist that necessary ethical truths require an explanation. Secondly, the PSR is controversial and is not accepted by many philosophers. Consequently, it is not particularly helpful in strengthening Craig’s demand for explanation, as it requires its own detailed justification.

Craig does, however, seem to have a point. If the necessity of certain ethical truths can be better explained with theism, perhaps this view should be preferred over non-theistic alternatives such as Wielenberg’s. Craig uses the example of “2+2=4” being a necessary truth that is grounded in Peano’s axioms, the set of statements that define the properties of natural numbers.

What then is Craig’s explanation for necessary ethical truths? Unsurprisingly, he thinks they are grounded in the necessary existence of God. Because God necessarily exists, certain ethical truths also necessarily exist. There are complications with this relationship,  though, and there is considerable debate about its nature.

Additionally, God’s necessary existence is considered by some theists to be “the ultimate brute fact”, as Swinburne puts it. Swinburne thinks God’s existence is contingent and has no explanation. This allows Wielenberg to claim that grounding necessary ethical truths in God still terminates in a brute fact, and so it is no more explanatory than regarding ethical truths themselves as brute facts. However many philosophers of religion disagree with Swinburne’s views here, regarding God’s existence as logically necessary. The explanation for God’s existence is generally regarded as lying within his own divine nature, i.e. God’s existence is self-explanatory. Wielenberg certainly makes no suggestion that necessary ethical truths are self-explanatory.

An issue for Wielenberg’s view is the correspondence between moral facts and our moral beliefs. If the universe contains basic moral facts, and these moral facts are causally inert, how do they become correlated with our beliefs? This is what Terence Cuneo calls the “remarkable coincidence”, and which Sharon Street considers is enough to reject moral realism – what she calls the Darwinian dilemma. Evolution is aimed at survival and fitness only. If it has also shaped the cognitive faculties that produce our moral beliefs, why should we think these moral beliefs have any relation to moral facts? This is really an argument about moral knowledge. Moral facts may exist, but how could we ever know what they are?

Rather than postulating a direct connection, both David Enoch and Wielenberg argue that there is a third factor responsible for binding moral facts to moral beliefs. This third factor is adaptive, but has only an indirect correlation with moral facts – our fitness enhancing beliefs also happen to produce our moral beliefs.

In Enoch’s view, survival is good, and since evolution is directed to survival, we develop beliefs about what is good. This is not particularly convincing, as it seems that Enoch has replaced one coincidence with another – how the results of natural selection just happen to align with moral truth. Wielenberg’s more nuanced argument is that we developed certain cognitive faculties that produce basic motivational tendencies that are adaptive. He focuses on tendencies that protect personal boundaries, as they will increase survivability. These cognitive faculties also allow us to develop beliefs about our rights.

Such arguments still seem to be question-begging. We believe survival is good, and that we have certain rights, but these are moral beliefs called into question by Street’s argument. Enoch and Wielenberg have not completely defused the evolutionary debunking argument, as it is known.

Another concern is what is known as the Anscombe intuition about moral obligations. In her famous paper Modern Moral Philosophy,  Anscombe argues that the unique authoritative character of moral obligations requires a law-giver. It is difficult to see how moral facts (even if they are obligations) provide the robust obligation that a divine command theory supplies, and Wielenberg struggles to justify this.


Recent non-theistic accounts of moral facts such those of Wielenberg and Enoch do provide an account for objective moral values without God. On these views, moral facts exist without explanation. It is a puzzle how moral facts are correlated with our moral beliefs, given that evolution aims at survival and fitness, and why we are obligated to pay attention to these moral facts is unclear.

Theists explain moral facts by appealing to the necessary existence of God. On the theistic view, moral obligation is also explained, and there is an account of why moral facts are correlated with moral beliefs.

There seems little reason to accept Wielenberg or Enoch’s view that brute moral facts just happen to exist and happily match our moral beliefs. Street’s Darwinian dilemma is persuasive, and on an atheistic view, it seems more realistic to attribute our intuitions about moral facts to evolutionary advantage rather than defend moral realism together with our moral knowledge.


*Moral facts and moral properties are often used interchangeably. For example, it is a moral fact that inflicting unnecessary pain on conscious beings is wrong. This can be restated as inflicting unnecessary pain on conscious beings has the property of being morally wrong. What about objective moral values? Moral facts are facts about objective moral values.


Is life meaningless without God?

Is life meaningless without God?

Claims that life without God is absurd, without purpose or meaningless are some of the most commonly voiced criticisms of atheism by Christians.

Philosopher and apologist William Lane Craig puts it bluntly: “If God does not exist, then life is futile”. Pastor Rick Warren states in his immensely popular book The Purpose Driven Life that “without God, life has no purpose, and without purpose, life has no meaning. Without meaning, life has no significance or hope.” According to most Christians, life is bleak without God.

Of course, they do not mean to imply that this demonstrates alternatives such as Christianity are true. Craig acknowledges this explicitly. Instead, he suggests that if the evidence for Christianity and atheism is weighed and found to be equal, then it would be “positively irrational to prefer death, futility, and destruction to life, meaningfulness, and happiness”.

Some atheists agree. For example, philosopher Julian Baggini admits, “I think it’s time we atheists ‘fessed up and admitted that life without God can sometimes be pretty grim”.

Curiously, though, many atheists do seem to lead happy and meaningful lives. At least, they seem to think so. Are they somehow deluded, or perhaps just not telling us the truth? It could be, of course, that Craig, Warren and other Christians who make these sorts of claims are themselves deluded or lying. However these seem to be very uncharitable explanations, so we need to dig deeper to explore this apparent contradiction.

It is important to do so, especially for Christians. We are prone to making negative claims about atheism such as its lack of meaning, and so Christian charity requires making an effort to understand why atheists might disagree.

So why do we have such opposing views about such an important topic? As is often the case in philosophy, the answer comes down to equivocation on terms. Words such as “meaning” and “purpose” are used by both groups, but are being understood in very different ways.

What do atheists understand a meaningful life to be? A good place to start is Erik J. Wielenberg’s Value and Virtue in a Godless Universe, where he explains different understandings of meaning.

Supernatural meaning is where purpose is provided by a supernatural being. For example, Christians may believe God has given them a reason for living. They are on a mission from God. Obviously, this understanding of meaning will never be shared with atheists.

Having external meaning is to make a difference in the world, making it a better place than it would have been had you never existed. And finally internal meaning is to live a life that leaves the individual better off for having lived it. It includes worthwhile activity that is good for the person living it.

To claim that atheism results in a meaningless life must therefore entail that even internal meaning is unachievable without God. But is this true?

Wielenberg discusses various arguments for this position. The first is the final outcome argument. Because eventually the universe is doomed to extinction, no events leading up to this outcome have value, including our lives. The pointless existence argument says that without a God to assign purpose, there can be no meaning. The nobody of significance cares argument claims that our lives can only have meaning if there is a God who cares about our lives.

There are various responses to these arguments such as those detailed in Thomas Nagel’s essay The Absurd. Nagel points out that we can easily ask the question, why is our ultimate end of glorifying and enjoying God meaningful? Craig responds that “with God we have reached an end that is truly worthy and capable of being an intrinsically good and meaningful stopping point”.

This leads to Wielenberg’s approach, who bases his counter-argument on Aristotle’s insight that some activities are intrinsically good. If intrinsically good activities exist, then engaging in them can give our lives internal meaning, no matter what the final outcome or who cares about it.

So to claim that life is meaningless without God requires that intrinsic goodness cannot exist without God.  Is this the case?

Wielenberg says no. His view is that some ethical truths are necessary truths. For example, suffering is intrinsically evil, and there is no possible world where this is not the case. Some ethical truths lie at the “very bedrock of reality, created by no one, under no one’s control, passing judgement on the actions and character of God and man alike”. They are brute facts, and to ask where they come from is misguided in the way it is misguided to ask where God comes from.  According to Wielenberg , “they come from nowhere, and nothing external to themselves grounds their existence; rather, they are fundamental features of the universe that ground other truths”.

Thus the argument about meaning reduces down to which of basic ethical truths or the existence of God are accepted as brute facts. Wielenberg has cleverly attempted to level the playing field with what he calls non-natural non-theistic moral realism.

Bearing this in mind, Christians should be cautious about making sweeping claims about atheism’s lack of meaning. Not only are there various interpretations of meaning, Wielenberg provides a plausible argument for the possibility of internal meaning without God. To counter it requires demonstrating his version of moral realism is untenable.



Has neuroscience destroyed the soul?

Has neuroscience destroyed the soul?

In a famous 1996 essay called Sorry, But Your Soul Just Died, writer Tom Wolfe predicted that the rapidly advancing field of neuroscience would soon destroy any notion of self or soul. The mind would be shown to be nothing more than brain processes, and the brain alone would be sufficient to generate the mind. It would be the final nail in the coffin for substance dualism, the view that the mind and the body are composed of different substances, where a substance is a constituent of reality.

What has twenty years of progress shown us? Has Wolfe’s prediction been realised?

According to Julien Musolino, the author of the The Soul Fallacy, published in 2015, the answer is an emphatic yes: “the current scientific consensus rejects any notion of soul or spirit as separate from the activity of the brain”.

Musolino is correct in his pronouncement – the current scientific consensus does seem to overwhelmingly reject a soul or spirit separate from the brain. But perhaps quoting the scientific consensus doesn’t properly address Wolfe’s prediction. After all, the scientific consensus in 1996 probably also rejected a separate soul or spirit as well. A more appropriate question is what evidence does neuroscience offer for science’s rejection of the soul? Or is this rejection primarily based on an a priori assumption of materialism?

To answer this question, we need to delve into neuroimaging, the technology used by neuroscience to explore the inner workings of the brain.

How neuroimaging works

One of the most frequently used neuroimaging techniques is functional magnetic resonance imaging (fMRI).

MRI is based on the principle of nuclear magnetic resonance. When certain atomic nuclei are placed in a magnetic field, they absorb and then emit characteristic electromagnetic radiation that can be measured. The frequency of this radiation depends on the nucleus and its environment. In MRI, hydrogen atoms are used as they are abundant in our bodies, being part of water and fat.

When neural activity in an area of the brain increases, neurons require more glucose for energy, and burning more glucose requires more oxygen. Blood flow to the area increases, bringing both glucose and oxygen, which is delivered via haemoglobin in red blood cells.

Haemoglobin has different magnetic properties depending on whether it is oxygenated or not, and these differences can be detected by MRI. This is known as blood oxygenation level dependent (BOLD) imaging.

Immediately after neural activation, blood oxygenation levels fall. It takes the vascular system several seconds to respond by increasing blood flow, which brings more oxygen. Oxygen levels peak after about six seconds before falling back to slightly below the initial levels.

The assumption behind fMRI is that the BOLD signal is linearly correlated with neural activity. During experiments, the subject’s head is placed in the MRI machine’s magnetic field, and it records the BOLD response throughout their brain for the duration of the experiment.

How experiments are conducted

In a typical experiment, participants perform an experimental task and a control task while brain activity is recorded. The control task and the experimental task share the same cognitive processes, but the experimental task has at least one additional process. For example, experimental participants might be shown a noun, and asked to state a verb that goes with the noun, while control participants are asked to repeat the noun. This is supposed to isolate the cognitive process that involves selecting an appropriate word from a different category.

The fMRI data of participants from each group is combined, and the brain activity responsible for the additional process is obtained by subtracting the activity from the control task, a technique known as cognitive subtraction.

Limitations of fMRI

Despite the widespread use of fMRI, we do not have a complete understanding of the relationship between BOLD signals and neural activity. Numerous factors are involved, and only broad correlations are currently possible. There are also a number of other limitations and caveats that are discussed below.

Not real-time

BOLD signals are at least five seconds behind the neural activity they are measuring. Temporal resolution is also constrained, as sampling frequencies add little information below one second. Neurons work many times faster, and so fMRI is currently of little help in understanding how brains work in real time.


fMRI does not measure the activity of individual neurons. Instead, its spatial resolution is divided into voxels, three dimensional cubes ranging from 1 mm to 5 mm in size. A voxel contains millions of neurons and tens of millions of synapses.


As the BOLD signal is relatively weak, care must be taken to control sources of noise, which include random neural activity, body movement and noise from the scanner. It is difficult to control all background effects, and subjects themselves can have variation in their neural activity from trial to trial.

There are a number of preprocessing steps performed to strip out noise prior to statistical analysis. For example, corrections are made for head motion, which moves voxels.

The data from each subject must also be normalised according to a standard brain “atlas” to eliminate structural variability between brains.

Statistical analysis

Interpreting raw experimental data to produce neuroimages is a complex statistical process. The infamous dead salmon study illustrated some of the issues. A salmon purchased from a store was shown photographs of people and asked to guess what the people were feeling. The researchers found that when the imaging data was analysed, a small part of the salmon’s brain showed activity in response to the photographs.

This is the multiple comparisons problem – if enough comparisons are performed, at least some of them will return positive results, even if they are false. Because fMRI scans divide the brain into 50,000 or more regions, they are very susceptible. Corrections can be made to account for the problem, but at the time of publication, 25-40% of fMRI studies were not doing so. Fortunately, this has dropped to around 10% by 2012 and is hopefully dropped further since, but it shows the complications involved.

Inhibitory neural activity

There are some indications that inhibitory neural activity may also increase the BOLD response, which obviously casts doubt on interpretation. More research is required in this area.

Cognitive subtraction

Recent research casts doubt on the technique of cognitive subtraction, used to isolate brain areas that contribute to a cognitive task in almost all brain mapping experiments. When subjects engage in an experiment, they suppress certain brain activity, and when they release the suppression, activity shoots up. So some parts of the brain show increased activity for less demanding tasks – a form of cognitive addition rather than subtraction.

Glial cells

Almost 90% of the brain is composed of glial cells, not neurons. For a long time glial cells were regarded merely as insulators for neurons, but research is now indicating that a type of glial cell called astrocytes may be involved in neuron signalling. Astrocytes have as many as 30,000 connections with surrounding cells, far more connections than neurons. According to researcher Andrea Volterra, “if glia are involved in signalling, processing in the brain turns out to be an order of magnitude more complex than previously expected”. For decades neurons have been the focus of brain research, and if astrocytes prove to be significant, a radical revision would be required. For now, their involvement is debated and being actively researched.

Are neuroimages photographs?

It should be clear from the explanation of fMRI above that neuroimages are not photographs of brain activity, despite similarities in their appearance.

fMRI does not directly measure brain activity, and data is not concurrent with the brain activity it represents. The data is highly preprocessed, and typically is a combination of results across multiple subjects, not a single brain. The end result is a statistical representation of a highly complex system.

1206 FMRI

The apparent similarities between neuroimages and photographs is problematic when it comes to interpretation by non-specialists.

According to Adina L. Roskies, “photography enjoys a privileged epistemic status”. Photographs are closely tied to reality, and accurately represent many of the qualities of their subjects. Importantly, we have a clear grasp of the causal relationship between photographs and their subjects. We regard a photograph as an objective representation, unaffected by the photographer’s beliefs.

Unfortunately, when non-specialists view neuroimages, they think they are seeing photographs of brain activity, and consequently find them compelling. They wrongly attribute the epistemic status of photographs to neuroimages, and develop an exaggerated concept of what they can tell us about the brain, which becomes part of popular culture.

What do neuroimages tell us?

As noted previously, neuroimages tell us little about how the brain works in real time. Instead, they provide information about which brain areas are correlated with particular mental events or stimuli. This is at a coarse level of millions of neurons, so if activity is occurring on a smaller scale, fMRI may not capture it. Given that it is difficult to discriminate between excitatory and inhibitory activity, we have little idea of what is going on at the level of individual neurons. That requires single-unit recordings, an invasive technique that involves inserting microelectrodes in the brain. For ethical and practical reasons, this can rarely be used, at least on humans.

Importantly, research so far shows that many regions of the brain have fairly general functions – a brain region may be engaged by many different cognitive processes. Specific cognitive processes involve networks of regions – they do not work independently. To determine the function of a particular region requires examining all of the cognitive processes that engage it. To exhaust all the possibilities for each region requires extensive research.

Correlation, dependence and causation

fMRI studies have established correlations between mental functions and areas of the brain, not causation. How might causation be established? Would this refute the idea of an immaterial mind or soul?

Brain damage is one possibility. When a person’s brain is damaged, it seems that their mind is damaged. From our fMRI correlations, we can reliably predict which mental functions will be impaired by damage in different regions of the brain. Cases such as Phineas Cage demonstrate that even our personalities can be radically changed when certain injuries occur. It would seem this establishes a degree of dependence of mental functions on the brain as well as correlations, although rigorous investigation requires the ability to safely deactivate and reactivate regions of the brain.

Doesn’t this dependence demonstrate that the mind is identical with or caused solely by the brain?

Not according to substance dualists, who claim that the mind uses the brain to express its abilities. The interaction between mind and brain means that correlation and even dependence is expected. A damaged brain results in a damaged expression of mind, even though the mind remains intact. Very tentative support for this view can be found in the rare cases of terminal lucidity primarily in Alzheimer’s patients.

What about consciousness?

What does neuroscience’s current progress tell us about the existence of the soul, or on a more philosophical level, about whether the mind and the brain are separate substances? For substance dualists, the mind is the soul, and so if neuroscience can explain the mind in its entirety as brain processes, then the soul is generated by the brain. It cannot be a separate substance.

To explain the mind, neuroscience must explain consciousness.

A science of consciousness must describe and explain the principal features of consciousness, and this involves two different types of data. Third-person aspects of consciousness are the “easy” problems. When a conscious system is observed, there is a range of specific behaviour accompanied by neural phenomena. For example, take someone listening to music. The third-party data involves the music, the effects on the ear and the auditory cortex of the brain, and the responses of the subject. All these must be explained in terms of neural mechanisms. But in addition, there is the “hard” problem of consciousness – the problem of explaining the subject’s subjective experience of listening to music. This is the first-person aspect of consciousness.

Neuroscience is making progress on explaining the third-person data, although the issues involved are anything but “easy”, particularly given the current limitations of fMRI. But presumably technology will eventually improve to the point that we can accurately correlate neural activity with mental functions to the level of single neurons. At this point we would have an incredibly detailed, complex map of what neurons are associated with each cognitive process. We may even be able to demonstrate causality.

What about first-person data? It is difficult to gather first-person data, as it is only indirectly available. We must rely on subjects’ verbal reports, which are hard to report accurately for experiences that are rich in detail.

Even if we can successfully gather first-person data, we are still left with the the “hard” problem of explaining how neural activity creates our subjective experiences. This is often known as the explanatory gap, and it is an open question in philosophy whether it can be resolved. Philosophers of mind have proposed numerous strategies to bridge the gap. Proposals range from extremes such as denying we have subjective experiences at all, to views such as panpsychism, the view that consciousness is a universal feature of matter. Substance dualism, of course, does bridge the explanatory gap.


One of the primary technologies used in neuroscience is fMRI – a relatively crude tool whose theoretical basis is not fully understood. Interpretation of fMRI data is also a complicated process. There are also uncertainties surrounding the role of astrocytes, and future research could result in a significant revision of how they interact with neurons and contribute to brain processes. So caution is required in when it comes to claims of what neuroscience has proven about the mind.

Neuroscience has made some progress on the “easy” problems of consciousness, establishing a number of correlations between regions of the brain and specific mental functions, but there is much yet to learn. Brain damage and resultant impaired mental functions indicate dependence of the mind on the brain, but dualism does account for this.

The “hard” problem of consciousness – subjective experience – is largely unexplored, and there are severe obstacles in producing an adequate explanatory account. However if the mind is to be explained as processes generated entirely by the brain, such an account is required.

It is clear that currently neuroscience is a very long way from destroying the soul, and any claim to the contrary is vastly overstating its capabilities and achievements.



Countering the simulation argument

Countering the simulation argument

The simulation hypothesis

In a wide-ranging interview at California’s Code Conference 2016, billionaire entrepreneur Elon Musk discussed the idea that we might be living in a computer simulation. Based on the previous 40 years of computer games evolution, he claimed that sooner or later “the games will become indistinguishable from reality”. He argued that at this point in the future there will be billions of computers running games that mimic reality. Therefore, the “odds that we are in base reality is one in billions”.

Musk’s basic point is that because there will be billions of instances of highly advanced virtual reality games being run in the future, we are almost certainly part of one of those virtual realities.

The simulation hypothesis was also recently the topic of the 2016 Isaac Asimov Memorial Debate, where possible evidence for this scenario was raised in a fascinating discussion.

Oxford philosopher Nick Bostrom is well known for his simulation hypothesis, discussed in his  2003 paper Are you living in a computer simulation? Bostrom provides some detailed calculations and comes to a similar conclusion  – there will eventually be ample computing power available to run simulations at the level of detail required. Bostrom calls this stage of technological development the “posthuman” stage of civilization. He uses a probabilistic argument to show the three options are i) we will be extinct, or ii) uninterested in running “ancestor-simulations”, or iii) we are in a simulation. In the absence of knowledge of the future, Bostrom assumes each option has a probability of a third. That is, if our descendants exist and they do run ancestor-simulations, we are almost certainly in one now. Of course if we are in a simulation, they are not our descendants, but rather descendants of the real human race (or whatever species created the simulation). Bostrom also notes the possibility of nested simulations, where our simulation creators may themselves be part of a simulation, and so on.

Putting the argument another way, Bostrom concludes that “unless we are now living in a simulation, our descendants will almost certainly never run an ancestor-simulation”, and estimates the probability of us being in a simulation as one chance in three.

Philosopher Julian Baggini attributes fascination with the simulation concept to “a common desire for there to be more to life than the interregnum between cradle and grave”, perhaps because of the possibility of virtual immortality.

Simulation and theism

Given the apparent logic of Bostrom and Musk’s case, theists need to take their arguments seriously, particularly because the possibility of being in a simulation seems incompatible with theistic religions (although not necessarily with theism itself).

For example, it implies that human history is simulated, and so there is reason to believe that it bears little or no relationship to real human history (if human history exists at all). Important events in the history of each religion are likely to be false, and the religions themselves invented by the simulation creator. Of course, this also has implications for naturalism, as the development of science and all our scientific knowledge would also be simulated.

The simulation argument also offers little support to theistic intelligent design. Musk and Bostrom are suggesting naturalistic beings are likely to be responsible for the apparent reality we are experiencing. These could be humans themselves (or perhaps our evolved descendants) in the (apparent) future. They could even be aliens. The rapid development of virtual reality (VR) games provides a cogent rationale for this scenario.

It should be noted that the simulation hypothesis does not purport to offer an explanation for our ultimate origins – rather its purpose is to explain the existence of our current apparent reality. In this sense theism can still be accommodated, where God is either the simulation creator himself, or is responsible for creating the simulation creators. There is, however, no equivalent game-playing rationale for why God might create a simulation, although of course this is still a possibility.

Could we know?

Is there any way we could determine if we were part of a simulation? Yes. Obviously, the VR creator could choose to reveal this to us directly, or perhaps they could leave a series of clues that allow us to infer our status. That could even be the point of the game!

Another possibility is detectable flaws in our simulation. It would be unnecessary to model every part of a simulated universe in equal detail. An optimisation would be to make realistic only the “region” containing simulated intelligent life. If we are the primary focus of the game, there would be no need for anything detailed beyond our programmed limits. We might be able to detect subtle breakdowns in virtual reality if we investigate the edges of where we can explore. Of course, as Bostrom notes, our brain states could be retrospectively edited by the simulation creator if they did not wish us to know.

The problem of evil

Baggini thinks there is a virtual problem of evil for the simulation hypothesis. He asks “if people like us created this virtual world, why on earth are the diseases so nasty, the poverty so widespread and the television so awful?” The problem of evil is one of the stronger arguments against theism, so is it effective against the simulation hypothesis?

No. Baggini clearly hasn’t indulged in survival horror games such as the Resident Evil series or The Walking Dead, which make our world look benign in comparison.There is no virtual problem of evil if the creator has no pretensions of goodness and enjoys virtual suffering. Given that the simulation creators are likely to be future humans, it seems entirely possible the evils of this world have been created by them.

Additionally, simulation creators may not realise that we are conscious beings. From their perspective we may just be extremely sophisticated, self-modifying AI programs which cannot experience suffering.

The real issue for the simulation theory

There are two assumptions underlying the simulation hypothesis.

Firstly, it uses an empirical argument based on our technological progress to conclude that our world is quite likely to be a simulation. But if we are in a simulation, doesn’t that undermine the empirical argument, as our technological progress must be simulated? How do we know anything at all about the underlying reality? Bostrom says if this is the case, we do know that the underlying reality permits simulations, and it contains at least one – ours. That means his third option is true. Conversely, if we are in reality, then the empirical argument is valid and one of Bostrom’s three options (extinction, disinterest in simulations, or simulation) holds. So the hypothesis seems reasonable.

Secondly, there is the issue of consciousness.

The crucial difference between the simulation hypothesis and The Matrix is that the latter is a brain-in-a-vat scenario – a simulation of the external world being fed to the brain. In The Matrix, human minds exist – we are conscious and our minds are still responsible for subjective experience. In the simulation hypothesis, human minds are generated by the simulation itself, and so the simulation must generate our consciousness.

Bostrom acknowledges that his argument requires the assumption that “mental states can supervene on any of a broad class of physical substrates”, including a computer, and that “a computer running a suitable program would be conscious”. Basically, the claim is that consciousness can be generated by replicating brain processes in sufficient detail.

This view is known as strong artificial intelligence, or strong AI, and it is a controversial position in philosophy of mind. Bostrom’s conclusions are of little significance unless strong support can be shown for this position.

The Chinese room

The question of whether AI systems are capable of consciousness has been raised since the earliest days of computer systems. Alan Turing, an AI pioneer, dismissed such questions as meaningless, and in 1950 proposed instead a behavioural test which he called the imitation game.  This involves a person remotely interrogating another person and a machine, and attempting to determine which is the computer based on their responses. This scenario and variations of it are now known as the Turing Test.

There have been many criticisms of the Turing Test, the best known being John R. Searle’s Chinese Room argument against computers having cognitive states. The Chinese room involves someone who does not read Chinese alone in a room with a set of instructions in English for manipulating Chinese symbols. Questions in Chinese are passed into the room, and the instructions are used to produce Chinese symbols that are the answers to the submitted questions.

The point of this thought experiment is that the person in the room does not understand Chinese, but is capable of passing a Turing Test for understanding Chinese. This is analogous to a computer performing symbol manipulations even to the point of passing a Turing Test, but having no understanding of what it is doing. As Searle puts it, “syntax is not the same as, nor is it by itself sufficient for, semantics”.

Searle’s Chinese room argument has been a powerful argument against strong AI that has provoked a great deal of discussion. There is currently no consensus as to the soundness of the argument, but it has not been conclusively refuted. Consequently, it remains an issue for the simulation argument.


The Chinese room analogy points to certain characteristics of consciousness that it seems doubtful a computer system could emulate.

One of these is intentionality. Our mental states are about things other than themselves, and this is called intentionality. Because the Chinese room has no understanding of Chinese, it lacks intentionality – its internal states are not about Chinese at all. The Chinese room argument shows that this is an issue for computer systems in general. How can electrical signals produced by computer hardware be about things, other than as directed by the external intentionality of the programmer? Of course, the underlying point is that the Chinese room is not conscious with respect to understanding Chinese.

The “hard” problem of consciousness

Intentionality is an unresolved issue for computational theories, but the “hard” problem of consciousness – accounting for the properties of experience known as qualia – is even more so. What is it like to feel pain? What is it like to see the colour red?

How could computer programs have qualia? Again, it is difficult to imagine how electric circuits can give rise to subjective experience.


Intentionality and qualia are actually problematic issues for the more general thesis of physicalism – the view that everything real is something physical or supervenes on something physical.

Strong AI is based on computational theories of mind,  which regard the mind as a computational system. By default they are physicalist theories, relying as they do upon a purely physical substrate of silicon chips and electrical signals. Physicalism can be rejected for substance dualism when it comes to human minds, but obviously substance dualism is not an option for computational theories.

There are a number of arguments against physicalism, and as strong AI is physicalist, they are equally applicable against it. However the increasingly popular physicalist solution of panpsychism is not available to strong AI proponents. Panpsychists such as Galen Strawson believe  consciousness is somehow a fundamental part of physical reality. Strong AI does not have this option, unless by some astonishing coincidence the computer hardware manages to generate consciousness – and this somehow interacts with executing AI programs. This is the interaction problem for AI!

Similarly, simulation theories can’t rely on panpsychism, as their worlds are entirely virtual. So the remaining options are eliminativism or epiphenomenalism. Eliminativism denies that we have subjective experiences, while epiphenomenalism denies that our minds have any causal powers. Both options seem incompatible with our intuitions about our minds.


Bostrom has calculated that there is a one in three chance we are living in a simulation. Given the theory’s incompatibility with theistic religions, the premises of his argument require careful examination.

Unless strong AI is possible, Bostrom’s case founders. Searle’s Chinese room illustrates the difficulties, and the usual arguments against physicalism apply. If physicalism is true, Bostrom’s probabilities are meaningful, and it seems likely we are part of a simulation. But there are good reasons to think otherwise.


Bostrom, N. (2003). Are you living in a computer simulation? Philosophical Quarterly 57(211): 243-255.

Bostrom, N. (2016). The Simulation Argument FAQ. [online]. Available at: [Accessed 6 Jun. 2016].

Searle, J. (1980). Minds, Brains and ProgramsBehavioral and Brain Sciences, 3: 417–57