Ludwig Wittgenstein, one of the most influential philosophers of the 20th century, lived two lives. The first was when he wrote the "Tractatus Logico-Philosophicus" in which he carried logical positivism to its pinnacle and reduced all meaning to propositions of logic. This was a life of absolute certitude, exactness and precision. "Tractatus" left nothing in the dark.In his second life, Wittgenstein rejected the sharp formulas of logical positivism and advocated a view of the world that was based on complexities, uncertainties and intuitions. Instead of mathematical formulae and logical propositions as the foundation of reality, he spoke of "family resemblances" and "language games."This radical shift made Bertrand Russell, the famous British philosopher of the time, frustrated and angry, and he pitied Wittgenstein for giving up serious philosophy. As Wittgenstein's "Cambridge Letters" shows, however, it was Wittgenstein who became disillusioned with Russell and pitied his old-fashioned, stubborn rationalism and positivism.Wittgenstein had a strong personality. Everything he said or did was intense. His sentences were aphorismatic, his voice heroic. His choice students and followers adored him as a prophetic figure. His detractors ridiculed him as a charlatan devoid of philosophical discipline. Regardless of how one looks, the sharp contrasts between Wittgenstein's two lives says much about the tectonic shifts in modern Western philosophy.The first Wittgenstein believed that the world was made out of atomistic units. This "scientific fact" is the basis of everything we need to know about language and logic. If the physical world is atomistic, mathematical, precise and sharp, so must be the philosophy that interprets it. Philosophy ought to mirror the world as it is. Thus, it must be logic and nothing else. All else falls outside the concerns of philosophy and logic.This is where Wittgenstein said famously "whereof one cannot speak, thereof one must be silent." If logical positivism cannot make sense of something such as love or faith, philosophy must not say anything about it. In this narrow sense, he famously described the limits of our language as the limits of our world.This sounded majestic to the darlings of positivism in the early 20th century. But Wittgenstein soon realized, through the most extraordinary circumstances, that there is more to reality than just atoms and logical propositions. There is so much out there that cannot be squeezed into logical sentences and scientific formulations but which still make sense. How do you write a musical note? How do you explain the feeling of longing for a friend? How do you give a logical/scientific explanation of love, forgiveness, righteousness or courage? The conclusion was: Just because we cannot explain something in a narrow logical sense, we cannot reject it as meaningless.Instead of rigid logical propositions, Wittgenstein began to work with ambiguities, family resemblances, language games, and the mysteries of the ineffable. His research remained anchored in language and logic. He defined philosophy as "the only work that gives me real satisfaction." But his new outlook liberated philosophical thinking from the shackles of atomism and reductionism. He became an artisan or craftsman rather than an armchair philosopher.In his struggles to explain the proper relation between language and reality, Wittgenstein was testing the limits of philosophy. After he denounced the "Tractatus," he was still interested in what can and cannot be said in language. There was a clear shift from what can be "said" to what can be "shown." "Showing" entails more than logical propositions; it extends to making, doing, gesturing, exclamation, thinking, intuition and finally the ineffable. It liberates philosophy from the limitations of natural sciences and the hegemony of philosophical reductionism. But it also sets limits to what philosophy can and cannot do.In some ways, this is what al-Ghazali (d. 1111), one of the giants of the Islamic intellectual tradition, was seeking to do with his critique of Peripatetic philosophy in the 12th century. Ghazali faulted the Muslim followers of Aristotle, mainly al-Farabi and Ibn Sina, for their epistemological hubris and incoherence. He charged them with stepping outside the boundaries of philosophy.As a traditional Muslim scholar and intellectual, Ghazali was trained in both the religious and philosophical sciences. He had such a mastery of Aristotelian philosophy that he wrote a book called "The Intensions of the Philosophers" (Maqasid al-falasifah), summarizing its main teachings. Ghazali was so successful with his summary that when this book was translated into Latin, many Latins took him to be a follower of Ibn Sina.Ghazali criticized Muslim Peripatetics for turning philosophy into a supposedly all-inclusive metaphysical worldview and daring to substitute it for religious faith. Their work on logic and mathematics was commendable. Their epistemology was only partly true. But it was in metaphysics that they erred colossally and stepped outside the boundaries of philosophy. With the political developments of his time in the background, Ghazali passed a merciless judgment on the philosophers and declared them outside the faith of Islam for holding three views: that the universe was eternal, that God did not know the particulars and that resurrection in the hereafter will be spiritual only.Sunni theologians and jurists took this verdict as a condemnation of all philosophy. The Orientalists declared this end of philosophical thinking in Islam. As Sunni theology and philosophical mysticism Ghazali and Ibn al-Arabi grew stronger, Peripatetic philosophy took a back seat. But philosophical thinking did not come to an end in the Muslim world. It took different forms.Ghazali criticized Aristotelian philosophy for venturing into areas in which it was not properly equipped to tread. In his eyes, philosophy, as represented by al-Farabi and Ibn Sina, was stepping outside its own self-declared boundaries. It was trying to articulate what cannot be articulated with logical formulas and "demonstrative proof" (burhan) alone. With an epistemological hubris, the philosophers had forced their way into metaphysics with tools that were not proper to the task. They tended to marginalize or reject that which they were unable to explain. Instead of reducing reality to what they can know, said Ghazali, they should have acknowledged their limits and accepted what can and cannot be explained with discursive reasoning alone.The philosophers' mistake, however, does not make philosophy altogether wrong. Instead of throwing away all philosophy, Ghazali turned to philosophical mysticism and developed new perspectives on what can be "shown" through philosophical-mystical reflection, contemplation and intuitive thinking. The subtle detail in the title of his critique makes this point clear: Ghazali called his work the "Incoherence of the Philosophers" (falasifa) rather than "philosophy" (falsafa), implying that the Peripatetics were incoherent in their arguments because they had not lived up to the philosophical standards they themselves had set up. In fact, Ghazali ridicules the philosophers by claiming that they were simply "imitating" (taqlid) their Greek masters rather than doing serious philosophy on their own!Ghazali himself had a taste of the pains of philosophical certitude or lack thereof when he had a crisis of epistemology and questioned even the existence of the outside world. As he explains in his famous autobiography "Deliverance from Error" (al-Munqidh min al-Dalal), he overcame this crisis with the help of revelation and a proper use of his reason.Can philosophy set its own limits?Ghazali thought so, and worked to develop a broader view of philosophical thinking to accommodate what cannot be articulated with demonstrative reasoning alone. He saw logic and language as part of a larger reality that can be intuited and grasped with different epistemological tools.This seems to be the direction Wittgenstein took in his later philosophy. Even though Ghazali and Wittgenstein worked within very different conceptual frameworks, their quest for broadening the task of philosophical reflection presents important opportunities for the meaning of philosophy today.A famous story from Islamic history sums up the complimentary relations between knowing and seeing – a relation that emerges in the work of both Ghazali and Wittgenstein. After a meeting between a prominent philosopher and mystics (according to some sources they were Ibn Sina and Khwaja Abdallah Ansari, respectively), people asked them what they thought of each other. The mystic said of the philosopher that "he knows what I see," and the philosopher said of the mystic that "he sees what I know."How to combine knowing and seeing, demonstrating and showing, saying and un-saying all remain to be the essential task of philosophical reflection.