Abū Ḥāmid Muḥammad ibn Muḥammad al-Ghazālī (c. 1058–1111) is often referred to – by both Muslims and non-Muslims - as "the greatest Muslim after Muhammad".
Avicenna and Averroes (still well-known in the West) were largely forgotten in the Muslim world; though their influence in Europe was very strong. Ghazali, on the other hand, was more or less ignored in Europe; yet his philosophy gained a supreme position in the Muslim world and it kept that position all the way to the 20th century and beyond. In other words, two important sustainers of philosophy were forgotten in the Muslim world; whereas the destroyer of philosophy (in his own words) gained an overwhelming hegemony.
Ghazali was indeed a philosopher. However, the primary aim of his philosophy was no less than the destruction of philosophy. But in order to achieve that aim successfully, he needed both philosophy and its tools. Without such things, other Muslims - especially philosophers and educated Muslims generally - would never have taken him seriously. Ghazali could quite easily have gone the way of the proto-Wahhabis/Salafists Ahmad ibn Hanbal (780-855) and Taqi ad-Din Ahmad ibn Taymiyyah. Instead, he decided to fight fire with fire (or philosophy with philosophy).
Ghazali was an educated man with an interest in philosophy. Or, more correctly, he had a keen interest in - and concern with - the ways in which philosophy had done severe damage to Islam and to the faith of believers. He needed philosophy to make sure that his campaign against philosophy was successful. Had he simply dismissed philosophy (as Ibn Hanbal and many other Muslim fundamentalists had done), then philosophy in the Muslim world might never have been killed – as it effectively was by, roughly, the late 14th century. (That isn't to say that philosophy - in some watered down form - didn’t continue after that period.)
I'm well aware that many Muslims - and even some Western/European non-Muslims (e.g., historians and other academics; though not many – or any – philosophers) - have claimed the exact opposite about Ghazali. Rather than being the destroyer of philosophy in the Muslim world, they see him as being its defender and upholder. Some even claim that he kept philosophy alive in the Muslim world. I'm convinced that the primary reason for this view is the mistake of believing that because Ghazali was a philosopher (indeed a skillful one), that it somehow automatically followed from this that he must also have been an upholder and defender of philosopher. The latter simply doesn't follow from the former. Ghazali was an adept philosopher; though he was most certainly neither its defender nor its upholder; as I hope this essay will show.
As I said, Ghazali required philosophy in order to destroy philosophy. Part of that process of destroying philosophy was to provide Islamic theology and Islam itself with a strong foundation. That meant that in order to save Islam from philosophical attack, he had to give it a secure philosophical grounding. However, that philosophical foundation was but a slave (or ‘handmaiden’) of Islamic theology. It was a means to an end.
In order to achieve all this, Ghazali believed that he required at least a smattering of Aristotelian logic. He also required, at that time, various neo-platonic methods and concepts in order to bolster Sunni dogmas and teachings. Again, these neo-platonic methods and concepts, as with Aristotelian logic, were but the "slaves of Allah".
In a certain sense, Ghazali’s destruction of philosophy was successful; although it took around 300 years for Ghazali’s complete authority - in all matters philosophical and theological - to set in. In the end, Ghazali "made supreme a theology which was itself a slave of dogma" (as Roger Arnaldez put it).
I mentioned Ibn Taymiyyah (the primary theological inspiration for contemporary Wahhabis and Salafists) earlier. He was an extreme - though not an altogether uncommon - example of Islamic reaction. Ghazali, the "greatest Islamic philosopher", was also an extreme Islamic reactionary; though one who nonetheless allowed a certain amount of freedom for the sciences and for logic (the latter being only an "instrument of thought"); though certainly not for philosophy generally and particularly not for metaphysics. Ibn Taymiyah, on the other hand, regarded all philosophy, science, logic, etc. as un-Islamic and even as anti-Islamic (as the Wahhabis and Salafists still do today).
Consequently it is best not to regard Ghazali as simply another Muslim Avicenna or Averroes. His attitude to philosophy was very illiberal. In fact his position on philosophy was so extreme that he even had a (religious) problem with the Greek syllogism. The ironic thing is, however, that he used very good philosophical and logical arguments to criticise both the syllogism and philosophy as a whole. (In this sense he was a kind of 11th century logical positivist or even a Wittgensteinian.)
Ghazali always referred to philosophers with the definite article – "the philosophers". That is, he wasn’t against Philosopher X or Philosopher Y; or even against philosophical school X or philosophical school Y. He was against the philosophers – that is, all philosophers. Ghazali himself wrote:
“The source of [Muslims’] infidelity was their hearing terrible names such as Socrates and Hippocrates, Plato and Aristotle…. [the followers of the philosophers] relate of the how, with all the gravity of their intellects and the exuberances of their erudition, they denied the scared laws and creeds and rejected the details of the religions and faiths, believing them to be fabricated ordinances and bedizened trickeries.”
As a consequence of these ‘impieties’, ‘exuberances’ and ‘trickeries’, Ghazali demanded the death penalty for anyone practicing philosophy; for anyone holding the opinions of the philosophers; and even for anyone holding opinions derived from the philosophers.
As an example of his penchant for the death penalty, Ghazali demanded "the execution of any many who made a public declaration that the body did not share with the soul in immortality". Now of course this sort of thing also happened in Western Christian society up until the 17th century and beyond. The point is, though, that no great Western philosopher - Ghazali is deemed to be "the greatest Muslim philosopher" – ever demanded the silencing of philosophy, let alone the death penalty for those philosophers who said the wrong thing (which isn't to say the same about Christian clerics or theologians).
Ghazali’s General Criticisms of Philosophy & Science
Ghazali set out to place severe limits on philosophy. In fact those limits were so severe that philosophy in the Muslim world hardly survived his remonstrations.
Basically, according to Ghazali, if philosophy impinged on Islam in any way, then it should be forbidden. If it didn’t, then that was fine. In his well-known work, Incoherence of the Philosophers, he tells us what is in and what is out, philosophically speaking. What is in, or what is acceptable, is logic and mathematics. Why? Because, as Ghazali himself said, they have no "bearing on religion". It followed from this that when logic and mathematics are properly used, they shouldn’t be questioned. In fact any Muslim who does criticise logic and mathematics, according to Ghazali, is "an ignorant friend, who is worse than a learned foe".
But apart from logic and mathematics, all the other parts of philosophy were highly suspect.
Take ethics and political philosophy. (The latter never really took off in Muslim world primarily because politics is so closely tied to Islam’s general vision.)
When it comes to ethics (or moral philosophy), Ghazali believed that everything should be derived from the teachings of the prophets and the Islamic masters. These teachings shouldn't be questioned. This effectively meant that there should be no ethics or moral philosophy.
What about physics (science) and metaphysics?
These philosophical diversions were even worse than ethics and political philosophy to Ghazali. He had a particular distaste for metaphysics and said that the metaphysics of the Greeks contained "innovations and impieties".
One reason for Ghazali’s strong position against metaphysics is that it didn't provide Ghazali - and Muslims generally - with a "logical reasoning" which is "infallibly applied". This Islamic concern with infallibility and certainty runs through Ghazali’s work and indeed the whole of Islam. And because philosophy, especially metaphysics, can’t offer us infallibility or certainty, as can Islam or the Koran (in the eyes of Muslims), then they should be rejected. Logic, as simply "a tool of thought", can indeed offer us certainty or infallibility; though only when applied to things which are Islamic or taken from the holy books. In other words, logic is both a tool of thought and a "slave of Allah". (Incidentally, scepticism about the possibility, or existence, of certainty or infallibility runs throughout Western philosophy; beginning with Socrates and later Pyrrho of Elis to Descartes and Hume and then all the way to the logical positivists, Popper and beyond. Indeed it became a commonplace of scientists that infallibility and certainty aren't forthcoming in science.)
Ghazali wasn't altogether happy with the natural sciences either; except when they benefited Islam and its empires or when they were seen in strictly practical or technological terms. In his book Ihya ulum al-din, Ghazali says that much of natural science goes against Islam and sharia law. Consequently, Muslims should, or must, keep away from the natural sciences and even from independent thought itself. Instead they should rely exclusively on the words of Muhammad, the Koran, and hadith; as well as on the interpretations and commentaries of the scholars and masters.
In terms of the specifics of philosophy, Ghazali cited three of the most dangerous questions which the philosophers had asked and debated: the eternity of the world; Allah’s knowledge of universals and particulars; and the denial of bodily resurrection. Because philosophers dared to ask these questions, let alone answer them, they were declared takfir (‘unbelievers’) by Ghazali. Ghazali himself put the situation this way:
“They [the philosophers] are absolutely to be condemned as infidels on three counts. The first of these is the question of the eternity of the world, and their statement that all substances are eternal; the second is their assertion that Allah does not encompass in his knowledge particular events occurring to individuals; the third is their denial of the resurrection of the body.”
Ghazali’s Technical Criticisms
Ghazali was quite modern in his approach to causality. Yet here again, despite his ideas pre-dating David Hume’s by 700 years, all his positivistic or empiricist demolishing was done for Allah and Islam.
The official Aristotelian line before Ghazali - which is not to say that no philosopher questioned it - was that all connections between causes and effects were necessary. However, according to Ghazali (as Hume also put it much later), those so-called necessary connections cannot be experienced (or seen) and cannot be demonstrated by reason either.
Ghazali sounds even more Humean when he argued that experience (mushahadah) shows only that the effect occurs at the same time as the cause. You do not experience any necessity and neither can you reason to any form of necessity. Indeed necessity can never be experienced because it is a logical or metaphysical doctrine.
To continue the Ghazalis empiricist and/or psychologistic theme: the philosopher said that people carry out, as Hume put it, an ‘association of ideas’ which has nothing to do with any necessary connection between things or events. That is, because people often experience the same causes before the same effects, they become habituated to the connection and see it as being necessary.
Despite all that, Ghazali’s philosophical modernism is all carried out on behalf of Allah and Islam. So although the reasoning is impressive, his answers or solutions are far from being (philosophically) impressive.
Ghazali believed that all causal processes in the world are caused directly by Allah; who is the sole agent in the universe. That means that Allah is responsible for any necessary connections between causes and effects. Moreover, if Allah is indeed responsible, the Prime Cause as it were, then it is he who makes those connections necessary.Indeed he can make them non-necessary or contingent. Allah has the power, that is, to stop any causal connections between causes and effects. So, in that sense, they can’t be necessary at all. And even if they were necessary, that would be because Allah is making them necessary.
Now Ghazali becomes more theological (Islamic) and less philosophical. It is not only the case that Allah is responsible for all causal connections between causes and effects, Muslims, as Muslims, must believe that too. If the Muslim Aristotelians, including Averroes later, argue that the cause necessarily engenders the effect, or that the effect necessarily follows the cause, then that surely must take something away from Allah’s omnipotence. It would mean that necessary causation would occur independently of Allah’s will by virtue of its very necessity. In other words, Allah’s power would be limited by Aristotelian metaphysics. More religiously, believing in necessary causation would disallow the possibility of miracles, which Allah is deemed to be capable of in Islam. After all, one aspect of miracles is that they subvert the causes and effects which are otherwise firmly established in the world (such as water evaporating in the hot air or kicking a ball and it staying still).
Averroes (Ibn Rushd) disputed all this. He too used an argument which was used by a later Western philosophers. He employed what was effectively a psychological – rather than philosophical – argument. He claimed that Ghazali really did believe in necessary causation but that he ‘denies verbally what is in his heart’. (C.S. Peirce later said that Cartesian doubt, as expressed in the well-known Cogito, was sophistical doubt and that it too was not ‘believed in the heart’. In Peirce’s case, it was unreal doubt which was also philosophically and scientifically unproductive or not pragmatic.)
Averroes specifically had a problem with Ghazali’s position that necessary causality was all about the psychological reality of human habituation. That is, the belief in necessary connection is nothing but the result of human habit brought about for the simple reason that people repeatedly see the same cause-effect sequences every day of their lives.
This is the interesting bit. Ghazali rejected necessary causation to prove the power of Allah. Averroes embraced necessary causation in order to prove exactly the same thing.
This is how Averroes argued that the belief in necessary causation was a belief in Allah’s favour, rather than the contrary. Firstly he said that ‘he who repudiates causality actually repudiates reason’. What he meant by that is that the necessary causation which we experience in the world should tell us that Allah has fixed the world according to a pre-determined and fully causal pattern. This is what Christian philosophers believed both before Ghazali's time and after. Indeed this law-like, or nomic, nature of the world made science possible; as so many thinkers have explained. Denying necessary causation, or the nomic nature of the natural world, is to deny order and symmetry and therefore the very things which make science itself impossible. Indeed it can be argued that Ghazali’s rejection of all this did make science impossible in the Muslim world. If Muslims had followed the words of Averroes (whom they largely forgot about), rather than Ghazali, they would have realised that the ordered and causal nature of the world is fully discoverable by the human mind precisely because it is ordered and causal. Through discovering the (necessary) causal nature of the world, Averroes believed that we could discover many truths about the Maker of all that causal regularity and necessity. We could discover the First Cause - God.
The Greek Syllogism
Ghazali’s criticisms of the Greek syllogism are very strong when one bears in mind when they were advanced. They were part logical/philosophical and part psychological.
Firstly, the syllogism includes various premises/propositions – or statements – which were taken to be self-evident and therefore intuitively graspable as being either true or false. But as 19th century logicians would later say, such positions are examples of ‘psychologism’. How can logic rely on things being either ‘self-evident’ or ‘intuitive’? Or, as Ghazali put it, those persons who are considering the premises of syllogisms will have different aptitudes and varying degree of cognitive skill. Consequently any positions persons take on the premises - and the conclusions derived from them - will be suspect or questionable. If the self-evident nature of the premises can’t be guaranteed, then the conclusions of the syllogisms will be even more suspect.
Syllogisms also rely on various and many universals. Take the opening ('major') premise, ‘All men are mortal.’ That contains two universals or classes (in a later language): men and the class or mortal things. But such universals, according to Ghazali and many Western philosophers, ‘only exist in the mind’. Universals such as man, mortals - and even apple and the syllogism itself - are far removed from what philosophers, and Ghazali, call ‘particulars’ or ‘individuals’. Socrates is a particular man and Fritz the cat is a particular mortal thing. Ghazali argued that we know about Socrates and Fritz the cat, but we know nothing about man in the abstract or the class of mortals. Or at least such universal are some large distance from everyday life and experience. In fact Ghazali was not only a proto-logical positivist in certain respects, he was also a nominalist - living roughly 200 years before the great Western nominalist, William of Ockham (1285-1347). (Ockham of ‘Ockham’s razor’ fame. In this case, Ghazali was making using Ockham’s razor to get rid of universals.)
So it is ironic that all this very good and advanced philosophising was carried in order to destroy philosophy. Even partly to destroy logic itself. All this was simply to show that, in the end, only Islam, or the Koran and hadith, can provide certain knowledge and certain truth. Thus it was important, to Ghazali, to take philosophy, and even logic, down a peg or two. In this endeavor he was very successful, at least philosophically and logically (whether or not many Muslims, or even most educated Muslims, relied on his reasoning is another matter).
Universals & Particulars
Ghazali singled out Avicenna (Ibn Sina, 980-1037) for special attack.
Ghazali didn’t like Avicenna’s philosophical position that Allah can only have knowledge of that which is universal, not particular. (At that time universals were usually seen in terms of species and genera, as they still often are.) To Ghazali, this was a clear limitation on Allah’s omniscience as well as perhaps on his omnipotence. After all, doesn’t Allah know everything? Or, as Ghazali put it, in the Koran (34:3) it says that ‘not a single atom’s weight in the heavens or on earth is hidden from Him’. It follows, then, that Allah must have knowledge of particulars too. How could it be otherwise? (Of course all this hinges or how Ghazali - and other philosophers at the time - actually saw universals and particulars in philosophical terms.)
Averroes (Ibn Rushd, c1126-98), some 50 years later, attempted to rebut all these positions of Ghazali.
Averroes wrote a book in response to Ghazali’s Incoherence of the Philosophers. It was wittily (or at least I think it was a piece of wit) called The Incoherence of the Incoherence. In that book Averroes said that Ghazali made the mistake of conflating human knowledge with Allah’s knowledge. (Something you wouldn’t expect Ghazali to do.) The basic point, according to Averroes, is that humans distinguish between universals and particulars but Allah does not. This is shown with a strange argument.
The argument goes that we mortals make a distinction between particulars and universal primarily because our knowledge is a result, or effect, of the things known. Allah, on the other hand, is a cause of the things known. It seemed to follow from that argument that Allah neither has knowledge of universals nor particulars; but both at the same time (or, in a sense, neither).
Despite offering us an account of Allah’s special kind of knowledge of universals and particulars (or his not knowing them qua universals and particulars), Averroes does go on to say that Allah’s mode of knowledge is unknown to us (something which ties into much Islamic thought). This fusion of particulars and universals, as it were, in the mind of Allah, is part of his mystery; even though, as I said, Averroes did attempt to explain that mystery.
The Eternity of the World
Ghazali believed that philosophical heretics, ‘the philosophers’, argued that the world is eternal. Averroes denied that. He said that if the world were eternal, then it couldn’t have been created. Therefore Allah couldn’t have created it. And, as a Muslim, Averroes said that he could not have believed that, despite Ghazali’s contentions. Instead Averroes argued that the world is generated ab aeterno (from eternity). It is not clear what this means. However, Averroes did say that to argue that the world was created in time (muhdath) is to place limits both on Allah’s power and on his perfection. More precisely, believing that the world was created in time would mean that Allah could not have created the world at any other time than the time he did create it. It would also entail the question: why did he create it when he did create it and not at another time? In other words, in order to free Allah from these contingencies, he had to be taken out of time. Rather than being eternal (strictly speaking), Allah is outside of time.
The Resurrection of the Body
Avicenna, as well as Averroes later, denied bodily resurrection; or at least that was what many Muslims, including Ghazali, thought. You may think that the denial of bodily resurrection was a very sophisticated philosophical position to take at that time (the 11th century). However, Ghazali uses a sophisticated philosophical argument to show the opposite.
To put it plainly, Ghazali argued that ‘the philosophers’ had not proved the immortality of the soul (regardless of resurrection of the body). He is correct. There is no proof in this area. What is more, Ghazali wasn’t accusing the philosophers of not proving the impossibility of bodily resurrection or the possibility of the immortality of the soul. He was saying that both bodily resurrection and the immortality of the soul cannot be proved. Just as there is no proof of bodily resurrection (as Avicenna and others would have argued), so there is no proof of the immortality of the soul either (as Avicenna believed there is). So whereas Avicenna believed there is proof of the immortality of the soul but not of bodily resurrection, Ghazali believed that there is no proof of either. (Though it depends on how we, and how they, took the notion of proof or ‘demonstration’.)
That lack of proof was a good thing to Ghazali (just as it was for Kant 700 years later). Without proof, or demonstration, for either bodily resurrection or the immortality of the soul, Muslims had to fall back on the Quran and hadith for sustenance. That is, instead of proof, there is faith. More specifically, the resurrection of the body and the immortality of the soul were shown (though Muslims still talk about ‘proof’ when they talk about the Koran and other Islamic matters) in the Koran and hadith when they make explicit reference to the Day of Judgement when the souls of Muslim men will be united with their bodies.
Interestingly enough, if there had been a prior Ghazali (as it were), then the actual Ghazali would neither have had any philosophy to destroy nor would he have had the philosophical skills with which to destroy it. Ghazali and his memory effectively killed philosophy in the Islamic world.
Consequently it is extremely ironic that Ghazali is deemed ‘the greatest Islamic philosopher’. In fact that is largely true despite the remarkable fact that his philosophy was almost exclusively motived by a fear of philosophy and the parallel desire to make philosophy give way to Islamic faith.