Heidegger and Christianity

Martin Heidegger's relationship to Christianity is a busy field of research and has been for some time. This is the case not just because Christian thinkers have sought to appropriate Heidegger's work for their own ends – the likes of Rudolf Bultmann, Karl Rahner, and John Macquarrie immediately come to mind – but because Heidegger himself had a close personal connection to Christianity and it deeply influenced his thought both positively and negatively. Up until his mid-twenties he was a loyal Catholic, even intellectually so. As a graduate student, he understood himself to be a philosopher working within the Aristotelian-Scholastic tradition (albeit one who wanted also to engage with modern philosophy)Footnote ¹ and in 1915 submitted a Habilitationsschrift with the title Die Kategorien- und Bedeutungslehre des Duns Scotus.Footnote ² But by twenty-eight Heidegger was drifting away from a personal adherence to Catholicism and turning toward Protestantism, yet it is unclear how deep was his commitment to the latter or how long it endured.Footnote ³ Heidegger never definitively broke with Christianity of some form (Welte (Reference Welte and Neske1977), 256; Sheehan (Reference Sheehan and Guignon1993), 72).Footnote ⁴ But for the rest of his life he would shift back and forth between appreciation and critique of it. During the 1920s he gave courses and lectures on St Paul, St Augustine, the mediaeval mystics, Luther, and the relationship between phenomenology and theology (Heidegger (Reference Heidegger and Jaspert1996); (Reference Heidegger, McNeill, Hart and Maraldo1998c); (Reference Heidegger, Fritsch and Gosetti-Ferencei2004); Schlier (Reference Schlier and Neske1977)). At this same time, while he was teaching at the University of Marburg, he befriended Bultmann, and the two frequented each other's courses (Wolfe (Reference Wolfe2014), 153–154). In 1938 Heidegger wrote of his ongoing ‘confrontation with Christianity’ (Auseinandersetzung mit dem Christentum) and of how he still clung to some elements of it but had left others behind (Heidegger (Reference Heidegger, Emad and Kalary2006), 368). And in remarks dating from 1953–1954, responding to the suggestion that he is ‘at home in [Christian] theology’, Heidegger tells his interlocutor that ‘[w]ithout this theological background I should never have come upon the path of thinking’, adding that ‘[o]rigin always comes to meet us in the future’ (Heidegger (Reference Heidegger and Herz1971a), 10).Footnote ⁵ Heidegger requested a Christian burial and received one upon his death in 1976 (Welte (Reference Welte and Neske1977), 256).

Despite the extensive literature that exists on Heidegger's relationship to Christianity there are still important areas of this relationship that await careful study and evaluation. One of these is Heidegger's critique of the notion of ‘Christian philosophy’. Although many people have commented on this critique, there seems to be almost nothing of real depth.Footnote ⁶ In Europe (especially France) and North America in the 1930s Christian philosophy was the topic of much debate among Catholics (Renard (Reference Renard1941), 16–17). But Heidegger's own interest in the topic predates this debate and, by all appearances, developed independently of it (Van Buren (Reference Van Buren1994b), 54; Ott (Reference Ott and Blunden1993), 77–78).Footnote ⁷ There is no doubt that the young Heidegger thought of himself as a Christian philosopher in some sense (Ott (Reference Ott and Blunden1993), 77–78). Around the time of his Habilitationsschrift he was even in the running for a chair in Christian philosophy at the University of Freiburg (Vigliotti (Reference Vigliotti2001)). But five years later Heidegger was openly attacking the idea of Christian philosophy. Between 1920 and 1940 we find critiques of Christian philosophy in six different texts (Heidegger (Reference Heidegger and Hofstadter1982), 20–21; (Reference Heidegger1991a), 5; (Reference Heidegger and Krell1991b), 88; (Reference Heidegger, McNeill, Hart and Maraldo1998c), 20–21; (Reference Heidegger, Fried and Polt2000), 7–8; (Reference Heidegger and Colony2010), 72–76). While there is significant overlap in the reasons these texts offer for rejecting Christian philosophy, the critique in each case is sufficiently distinct that an attempt to treat of all of them adequately would probably require – in my estimation at any rate – something the size of a book.Footnote ⁸

In this article I shall consider one of Heidegger's critiques of Christian philosophy from the 1920–40 period, namely, the one we find in his lecture course on metaphysics from the summer of 1935, which was subsequently published in 1953 as Einführung in die Metaphysik (Introduction to Metaphysics). This is the more widely known of Heidegger's critiques and so, presumably, the most influential. It shall be my contention that Heidegger's reasons for rejecting Christian philosophy, as he articulates them in this text, are not ultimately persuasive.

Against Christian philosophy

The main concern of Heidegger's Introduction to Metaphysics is being (Sein) – a topic famously central to his thought – but at the beginning of the book there is also a well-known rejection of Christian philosophy. Heidegger claims that a Christian philosophy is like ‘wooden iron’ (hölzernes Eisen) and is simply a misunderstanding (Heidegger (Reference Heidegger, Fried and Polt2000), 8).Footnote ⁹ Philosophizing, he argues, entails posing the question about why there are beings at all rather than nothing (ibid., 8).Footnote ¹⁰ He calls this question the Grundfrage, the ‘fundamental question’, and sees it as leading to what he calls the ‘prior question’ or Vorfrage, which is about how things stand with being (ibid., 35). According to Heidegger, Christians are unable to ask the Grundfrage because they suppose that in the Creator-God they already have an answer to it. He does allow that Christians can act ‘as if’ (als ob) they are posing the question but he denies that they can do so authentically (ibid., 8). In saying that Christians can act ‘as if’ they are asking the Grundfrage, I imagine that Heidegger has in mind something like teachers when they ask their students questions to which they already know (or think they know) the answers. Christians asking the Grundfrage would, on Heidegger's view, be acting like these teachers. Their asking of the Grundfrage, and so their pursuit of philosophy, would be but simulacra. The clear implication is that doing philosophy requires being able authentically to pose the Grundfrage, and this cannot be done if we already have an answer to this question, or so Heidegger says.Footnote ¹¹

There is a second reason why Heidegger rejects Christian philosophy which seems even more radical than the first. The supposed Christian answer to the Grundfrage, says Heidegger, simply cannot be the answer because it has no relationship to the question. Here is how Heidegger puts it:

It would seem that the natural way to interpret these remarks is to regard them as saying that the Creator-God of Christianity cannot be the answer to philosophy's fundamental question because what philosophy is about just cannot be what Christian faith is about. And this is the case because, for Christianity, philosophy is foolishness, or so Heidegger alleges. If I think that your interests are foolish, then I probably do not see them as having any connection with mine. But where does Heidegger get the idea that Christianity takes philosophy to be foolishness? There is no explanation of this in the Introduction to Metaphysics. But in Heidegger's 1949 introduction to ‘What is metaphysics?’ he references St Paul's first letter to the Corinthians on this score (Heidegger (Reference Heidegger, McNeill and Kaufmann1998a), 288).Footnote ¹² There Paul writes:

In the essay Heidegger goes on to identify the wisdom that is spoken of here with philosophy.Footnote ¹³ There can be little doubt that it is this same passage from Paul that Heidegger is thinking of in the Introduction to Metaphysics. If Christians, then, offer the Creator-God as an answer to the Grundfrage, Heidegger is likely to tell them that they are not being true to the biblical basis of their faith.

Walter Kaufmann proposes a completely different way of interpreting Heidegger's second objection to Christian philosophy:

Now, I think Kaufmann's exegesis is entirely wrong. Heidegger obviously does explain why he holds that the Christian God cannot be an answer to his question. That explanation, as I have just said, is given when Heidegger says that Christianity regards philosophy as foolishness. But on the chance that the more obvious (to me) reading of the text is not the correct one, I would like to entertain Kaufmann's thesis. Kaufmann's Heidegger denies that the Christian God is an answer to the Grundfrage because this God is included among those beings whose existence we are asking about. If we are wondering why the Christian God exists, thinks Kaufmann, God cannot be the answer to that question.

A third reason for rejecting Christian philosophy is not openly stated by Heidegger but is implied, I believe, by these comments:

We can pose thoughtful questions about what is given in Christian faith, says Heidegger, but this is theology, not philosophy. To Christians who might wish to say that they are doing ‘Christian philosophy’ because they are posing thoughtful questions about Christian beliefs, Heidegger would no doubt respond: ‘You have it wrong. There is no philosophy going on here, only theology’. My sense is that Heidegger would want to say that any exercise in fides quaerens intellectum, faith seeking understanding, would always be theological and never philosophical.

These objections of Heidegger to Christian philosophy can be met, or so I shall argue in what follows.

Philosophy, Christianity, and answers

Does having an answer to the Grundfrage, or thinking that you do, disqualify you from doing philosophy? I do not think that it does. I do agree that any philosophy worthy of the name ought to have a basic interest in the Grundfrage (even if this is not the only question that ought to interest it). This is because philosophy is the love of wisdom and wisdom in its highest form would arguably be a knowledge of the first principles of things, whatever those turn out to be (Aristotle (Reference McKeon and Ross1941), 982a1).Footnote ¹⁴ Heidegger presents a similar view of philosophy in the Introduction to Metaphysics. ‘Very roughly speaking’, he writes ‘philosophy always aims at the first and last grounds of beings’ (Heidegger (Reference Heidegger, Fried and Polt2000), 10).Footnote ¹⁵ And the Grundfrage is definitely a question aimed at such grounds or principles. Yet do I cease to be a philosopher once I discover what those grounds or principles are, once I have an answer to the Grundfrage? I do not see why that should have to be the case. Certainly the possession of wisdom does not spell the end of my love for wisdom, that is, the possession of wisdom does not spell the end of philosophy for me. To borrow an example from Hegel, wine lovers do not cease to be wine lovers when they are drinking wine (Hegel (Reference Hegel and Haldane1995), 199–200). This would seem to be the case with most of what we love. Friends are not automatically unloved because we are with them. They are loved in their presence and in their absence. Surely, then, if Christians have an answer to the Grundfrage in the Creator-God, this by itself would not make Christian philosophy impossible, a contradiction in terms, as Heidegger supposes.

It is true that some philosophers understand the love of wisdom necessarily to mean the non-possession of wisdom, its inconclusive pursuit. Socrates sometimes speaks this way although I doubt that it should be taken as a consistent Socratic or Platonic doctrine. In the Phaedrus, for example, Socrates claims that only a god can be wise while human beings can at best be mere lovers of wisdom (Plato (Reference Hamilton and Cairns1961), 278d). In other words, human beings can only ever be on the hunt after wisdom, they can never be its possessors.Footnote ¹⁶ If this is not hyperbole or irony, I would again say that possessing what I love does not seem to hinder my love for it, and so I see no compelling reason to accept a conception of philosophy that assumes otherwise. Now, my thesis is not that we should replace the notion of philosophy as the pursuit of wisdom with that of philosophy as the possession of wisdom. In my own experience I find that I and other philosophers spend more time in pursuit than in possession of what we are after, and in this pursuit we are definitely doing philosophy (assuming that we do so because we love wisdom). I am only arguing that it does not seem necessary to me that the attaining of wisdom should bring philosophy to an end in the sense that once I have wisdom I am no longer a philosopher.

Heidegger himself would seem to be on the side of those who understand philosophy exclusively as the inconclusive pursuit of wisdom. As George Kovacs puts it, for Heidegger, philosophy is ‘the search for and not the possession of answers’ (Kovacs (Reference Kovacs1990), 148). Josef Pieper, speaking specifically in the context of the Introduction to Metaphysics, says that ‘for Heidegger ‘questioning’ would appear to mean essentially warding off every conceivable answer and closing oneself off to them’ (Pieper (Reference Pieper, Wald and Wassermann2006), 153). We already have reason to suspect that this is Heidegger's view of philosophy from his wanting to leave the Grundfrage an open question. This interpretation of Heidegger is confirmed when later in the Introduction to Metaphysics we read that philosophy ‘has constantly and always asked about the ground of beings. With this question it had its inception, in this question it will find its end’ (Heidegger (Reference Heidegger, Fried and Polt2000), 26).Footnote ¹⁷ Said in another way, the goal of philosophy is not an answer but to continue questioning, in particular, about the ground of beings. And my reply to Heidegger on this point is the one that I have already given: arriving at an answer, at wisdom, does not need to mean that philosophy is finished.

It should be noted that claiming to have an answer to the Grundfrage, that is, claiming to have wisdom about why there are beings at all rather than nothing, need not be the same as claiming to have a complete understanding of the matter. It need not be this unless claiming knowledge is the same as claiming comprehensive knowledge. But it seems unreasonable to equate knowledge with comprehensive knowledge. Surely it is possible to know something about x without knowing all there is to know about x. If I know, say, that olive trees grow better in limestone soils than in soils that lack limestone (which they do) but I do not know everything else that could be known about olive trees, surely this one true judgment about olive trees must count as knowledge about them. It would plainly be false if, in this situation, I were to say that I know nothing about olive trees. In a like manner, for Christians to suppose that they have an answer to the Grundfrage they need not also suppose that they fully understand the answer that they possess. There could be plenty about the answer that is still mysterious to them, provokes wonder, and requires further inquiry.

But is this how Christians see things? Or do they think that they have a comprehensive understanding of God? It is fairly standard in Christian theological epistemology to hold together the cataphatic and the apophatic, that is, to maintain the possibility of knowing God along with an admission of limits on this knowledge. Aquinas, for instance, while he holds that we can know that certain things are true about God, also denies that we can know God as fully as he can be known (Aquinas (Reference Aquinas1947), Ia 12.12; 12.13). But this same sort of position can be found in the New Testament too. St Paul, on the one hand, claims to be able to impart certain truths about God (Acts 17:22–32) and holds that God is known through creation (Rom. 1:19–20), while, on the other hand, he acknowledges God's radical epistemic transcendence (1 Tim. 6:16). All of this seems well summed up when Paul speaks of ‘knowing in part’ and ‘seeing through a glass darkly’ (1 Cor. 13:12).

Now, it might be objected to what I have been saying that Heidegger cannot possibly mean that philosophy can never claim to have answers to the questions it poses. Surely Heidegger understands that it makes little sense to ask a question if it is assumed from the outset that no answer to it is to be had. Heidegger may merely be saying that philosophy cannot begin with answers but must always begin with questions, questions to which it hopes to find answers. I think that the best reply to this objection is simply to direct the objector back to Heidegger's text. As we have seen, it suggests something stronger, viz. that Heidegger believes that it is philosophy's task to keep questions – including the Grundfrage – permanently open.Footnote ¹⁸ But supposing I were to concede that Heidegger is making a weaker claim, then in line with what I have been arguing I would say that questioning is not essential to philosophy, not even an initial questioning. It is not what makes philosophy what it is. It may be de facto true that philosophers ask questions and almost always begin with questions, but what makes them philosophers is not their questions, it is their love of wisdom, which can be loved even when it is possessed.

Is philosophy foolishness for Christianity?

Even if he were to grant that having an answer to the Grundfrage would not disqualify Christians from doing philosophy, Heidegger would certainly still want to press the objection that Christians cannot, in principle, have an answer to a question posed by philosophy. And this is so because Christianity, Heidegger insists, regards philosophy as foolishness. As we saw, Heidegger probably gets this notion from St Paul's first letter to the Corinthians. Jean-Luc Marion speculates that Heidegger's exegesis of 1 Corinthians on this point is influenced by Luther, which is not unlikely given Heidegger's passionate interest in the German ‘reformer’.Footnote ¹⁹ Heidegger had an intimate knowledge of Paul's thought, which he probably first began to develop in a 1920–21 lecture course on the phenomenology of religion (Heidegger (Reference Heidegger, Fritsch and Gosetti-Ferencei2004)), a course in which he also worked through ideas about temporality that would have an important place in his later work, especially Being and Time (Heidegger (Reference Heidegger, Macquarrie and Robinson1962)).Footnote ²⁰

One major problem for Heidegger's interpretation of 1 Corinthians is that Paul never literally says in the passage in question, nor anywhere else in the letter, that philosophy is foolishness. This is Heidegger's own gloss on what Paul writes about God making ‘the wisdom of this world foolishness’ and about the preaching of ‘Christ crucified’ as ‘foolishness’ to the Greeks who seek wisdom. But this gloss could be defended if Heidegger is able to show how it is warranted by the context of the letter, or by other things that Paul says in it, or by how it can be inferred from Paul's doctrines in his other writings. However, the only support for his reading that Heidegger manages is a reference to Aristotle, who, Heidegger says, speaks ‘quite explicitly’ of ‘philosophy proper’ as ‘that which is sought after’ (Heidegger (Reference Heidegger, McNeill and Capuzzi1998b), 288). Heidegger's rather astonishing argument would seem to be the following. Paul says that the Greeks seek wisdom and Aristotle says that philosophy is that which is sought after. So, Paul must be talking about philosophy when he mentions the wisdom pursued by the Greeks. And since Paul calls this wisdom foolishness, he is also calling philosophy foolishness. The tacit suggestion is that Aristotle's notion of philosophy somehow worked its way into Paul's thinking.

Paul's acquaintance with the philosophy of antiquity and its influence on him is a subject of much controversy. There seems to be little agreement among scholars about the nature of the influences, their extent, or where Paul would have encountered them.Footnote ²¹ Given this situation, it would be incumbent upon Heidegger to show that the parallel phraseology of Paul and Aristotle is more than just coincidence. But Heidegger does nothing to show this. Thus, it is hard to take his claim all that seriously.

Still, in Heidegger's favour, it must be mentioned that 1 Corinthians 1:21–23 has often been interpreted by Christian authors as dealing with philosophy in some manner. There is, nevertheless, no consensus about whether it should be taken as a rejection of philosophy, not even among early exegetes. Tertullian sees it as a rejection of philosophy tout court (Tertullian (Reference Greenslade and Greenslade1956), 35). But others have argued that it is only rejecting false philosophy, not all philosophy. Such is the line taken by Origen (Origen (Reference Chadwick1953), I, 13), and it is probably that of Clement of Alexandria as well (Clement of Alexandria (Reference Ferguson1991), I, 11).Footnote ²² But there are also a number of contemporary scholars who doubt that Paul is talking about philosophy here at all. J. Stanley Glen points out that the ‘proletarian’ character of the community at Corinth makes it unlikely that Paul is talking about ‘philosophy in the technical sense’ since it would have been improbable for them to have been involved with it (Glen (Reference Glen1965), 23). Paul Gooch contends that the wisdom that Paul criticizes is not philosophy as such but ‘epistemological hubris’ (Gooch (Reference Gooch and Moser2009), 96). Offering a reading similar to Gooch's, Stanley Stowers tells us that Paul's ‘focus is entirely on wrong attitudes and behavior in relation to the pursuit of wisdom’ and adds that ‘[w]isdom as such, or its pursuit, is not condemned’. The problem, he explains, is ‘any wisdom characterized by certain moral and epistemic vices . . . the pursuit and use of knowledge [that] is characterized by conceit, arrogance, and bragging’ (Stowers (Reference Stowers, Balch, Ferguson and Meeks1990), 258). On this view, what is at issue is not a human attempt to attain wisdom about God or anything else but going about this in the wrong way.

In light of the significant exegetical disagreements about how to interpret 1 Corinthians 1:21–23 and because Heidegger fails to provide anything like credible support for his gloss on the text, I see no good reasons to go along with that reading.

Kaufmann's reading of Heidegger

Walter Kaufmann, as I indicated earlier, has a different way of understanding why Heidegger denies that the Christian Creator-God can be an answer to the Grundfrage. According to Kaufmann, the reason for Heidegger's denial is that this God is among the beings whose existence the Grundfrage is asking about. Heidegger does not say this himself, but Kaufmann seems to believe that this is what Heidegger is thinking. But if this is what Heidegger is thinking, why does Kaufmann suppose that the Christian God's inclusion in the beings whose existence we are inquiring about would lead Heidegger to deny that he can be an answer to the Grundfrage? Unfortunately, Kaufmann does not explain.

Nevertheless, it is probably a safe bet (or a least a reasonable one) that the problem Kaufmann sees (and he thinks Heidegger sees) is that to take the Christian God to be an answer to the Grundfrage would be to take what is part of the explanandum to be the explanans. Doing this would appear to beg the question. If one of the beings whose existence I am asking about is God, if I am asking why it is that God exists at all, God cannot be the answer to that question.

Or can he? If God's existence can only be explained by something other than God, then to point to God as the explanation for his own existence would, indeed, be question-begging. But why should we assume that God's existence has its explanation outside God? Christianity regards God as uncaused. As Anselm tells us, the Supreme Nature ‘definitely does not exist through something other than itself’ (Anselm (Reference Davies, Evans and Harrison1998), 17), and as Aquinas says, ‘God does not have a cause’ (Aquinas (Reference Aquinas1947), Ia 3.7). If this is true, then we would look in vain for an explanation for God outside God. The explanation would be in God himself. Something about God, and not about anything else, would make it the case that he exists.

Kaufmann might ask what our proof is that God is the explanation for his own existence. And he would be right to do so. But we could also ask Kaufmann what justifies his assumption that something other than God explains God's existence. We could even ask why he assumes that any of the beings whose existence we are asking about require for their explanation something besides themselves. Perhaps they do. But why does Kaufmann think they do? He does not say. I do not see, then, how he can justify claiming (supposing, as seems plausible, that this is his view) that to regard the Christian God as an answer to the Grundfrage is question-begging.

But there might be grounds for rejecting Kaufmann's reading of Heidegger altogether, so that refuting Kaufmann becomes irrelevant to dealing with Heidegger. What are these grounds?

It is well known that the early Heidegger maintained that philosophy must, methodologically speaking, be ‘atheistic’. We find statements to this effect already in his 1921–22 lecture course on Aristotle: ‘Philosophy, in its radical, self-posing questionability, must be a-theistic as a matter of principle’, Heidegger insists. And ‘[p]recisely on account of its basic intension’, he observes, ‘philosophy must not presume to possess or determine God’ (Heidegger (Reference Heidegger and Rojcewicz2001), 148). Once again we encounter Heidegger's conception of philosophy as above all about questioning, and this seems to be what makes it ‘a-theistic’. The position is probably better described as methodological agnosticism since atheism would suggest having come to a conclusion about God. This approach to philosophy arguably continues even into the later Heidegger. In the ‘Letter on humanism’ from 1946 Heidegger says that his work ‘can be theistic as little as atheistic’. But he urges that this ‘is not because of an indifferent attitude, but out of respect for the boundaries that have been set for thinking as such, indeed set by what gives itself to thinking as what is to be thought, by the truth of being’ (Heidegger (Reference Heidegger, McNeill, Hart and Maraldo1998c), 267). Whatever the reason, even later in his career, we see that Heidegger wants to leave the God-question open. In fact, he wants to (or should want to) say as little as possible about it.Footnote ²³

We have every reason to suppose, therefore, that Heidegger sticks to his methodological atheism or agnosticism in the Introduction to Metaphysics, which was given as a lecture course in 1935. But if he does stick to it, why should we think, as Kaufmann does, that the question about why there are beings at all instead of nothing includes God? It seems quite improbable that Heidegger does intend to include God in this question.

Theology or philosophy?

‘Faith seeking understanding’, writes Étienne Gilson, ‘is the common motto of all Christian theologians and of Christian philosophers as well’ (Gilson (Reference Gilson1960), 63). Heidegger would accept the first part of this conjunction but certainly reject the second part, for it appears to be his judgement that there can be no truly philosophical handling by Christians of what they accept in faith. Any thoughtful questioning of faith, he has told us, is theology, not philosophy.

Clearly Heidegger believes that philosophy and Christian faith take two very different approaches to their material. But what are these different approaches? Heidegger would want to say that the difference is that philosophy is a permanent posing of questions whereas Christian faith can, at best, pose questions (or only some questions) temporarily. This much is certain from the text of Introduction to Metaphysics.Footnote ²⁴ However, I have shown that there is no necessity that philosophy as philosophy eschew true answers to the questions it poses. It will not do, in other words, for Heidegger to distinguish philosophy from faith in the foregoing way.

In whatever manner Heidegger desires to separate the work of philosophy from the reflection of Christians on what they believe, we know that he denies that such reflection could be philosophical. But I would suggest, on the contrary, that there is a plausible – and quite obvious – way of understanding it to be philosophical.

Suppose that, as a Christian, I hold that the God I believe in is the reason why there are any beings at all rather than nothing. Does such a God, who is the origin of all beings, exist? Suppose I set out to show that he does without any formal appeal to Christian revelation. Here I am setting out to attain wisdom about the fundamental principles of things. Is this not philosophy? You cannot say that, formally speaking, I am simply taking it on faith. I am not counting on revelation to do any work whatsoever in the case I make for the existence of this God. The fact that I happen to believe in this God by faith makes no difference to the arguments I construct.Footnote ²⁵

Consider an analogous case. Let's go back to the olive trees I spoke about earlier. Suppose in a book about olive trees I read about the fact I mentioned before, namely, that olive trees grow better in limestone soils than in non-limestone soils. The book being written by an expert on the subject, I come to believe that this characteristic is true of olive trees. Moreover, I have no doubts about it at all because I have found no serious reasons to think otherwise. Yet, suppose I perform an experiment to prove the truth of my belief to a friend who does doubt it. I plant one olive tree in limestone soil and another in non-limestone soil. I am not now appealing to the book I read nor does the fact that I still believe what it reports make a difference to my efforts to convince my friend about the value of limestone soil for olive trees. The experiment will stand or fall on its own.

Is what I am proposing not just a way of trying to justify what I already believe? In a sense it surely is. Yet, there is hardly anything fallacious about this. If I can offer a decent or even demonstrative argument for what I hold to be true, it really makes no difference when (nor, of course, how or why) I came to believe it. And, again, if I do not ask you to accept any premise that depends on teaching specific to Christian revelation, you cannot say that I am doing theology rather than philosophy.

But now a different objection might come up. If you grant that I can engage in independent philosophical reflection on what I believe as a Christian, you might now be prepared to say that I am doing philosophy but then you might ask whether this should be called Christian philosophy. After all, I am not depending on anything specifically Christian to make my arguments. Still, if as a Christian I believe that there is a God who is the ultimate source of all beings and I set out to show that such a God exists without calling on the formal assistance of revelation, then in my view this undertaking would merit the appellation ‘Christian philosophy’. Its motivations alone are one thing that would plainly warrant calling it this.

Clearing a path

Heidegger's critique of the notion of Christian philosophy in the Introduction to Metaphysics does not hold up. The idea of philosophy that it depends on – philosophy as an inconclusive quest – need not be accepted as the only legitimate way to think of philosophy. Heidegger's claim that Christianity regards philosophy as foolishness is not evidently supported by the text of St Paul on which it draws. Kaufmann's alternative reading of Heidegger on why the Christian God is not an answer to the Grundfrage fails to make Heidegger's case any stronger and is probably not even a correct reading. Finally, Heidegger is simply wrong to think that it is not possible for Christians to engage in independent philosophical reflection on what they believe in faith.

Christian philosophy under some description is a possibility. I have not made much of a positive case for it here since my chief purpose was to show how Heidegger's critique of Christian philosophy in the Introduction to Metaphysics fails. Sometimes the negative moment, the moment of Destruktion – to take a term from the Heideggerian lexicon – must proceed the positive moment to clear a path for it. And clearing a path is mostly what I have tried to do here.Footnote ²⁶