forms of treatment by putting into doubt traditional forms based on intuitive appeal rather than empirical evidence. In the history of philosophy, skepticism has often played a productive role not just for skeptics but also for non-skeptical philosophers. This is due to its critical attitude that continues to challenge the epistemological foundations of a great variety of philosophical theories. This challenge can help to keep speculation in check and may provoke creative responses transforming the theory in question in order to overcome the problems posed by skepticism. According to Richard H. Popkin, "the history of philosophy can be seen, in part, as a struggle with skepticism". In this regard, it has led many contemporary philosophers to abandon the quest for absolutely certain or indubitable first principles of philosophy, which was still prevalent in many earlier periods. Skepticism has been an important topic throughout the history of philosophy and is still a widely discussed subject today. Philosophy As a philosophical school or movement, skepticism arose both in ancient Greece and India. In India the Ajñana school of philosophy espoused skepticism. It was a major early rival of Buddhism and Jainism, and a possibly major influence on Buddhism. Two of the foremost disciples of the Buddha, Sariputta and Moggallāna, were initially the students of the Ajñana philosopher Sanjaya Belatthiputta, and a strong element of skepticism is found in Early Buddhism, most particularly in the Aṭṭhakavagga sutra, but it is inconclusive the total effect these philosophies had on each other. Since skepticism is a philosophical attitude and a style of philosophizing rather than a position, the Ajñanins may have influenced other skeptical thinkers of India such as Nagarjuna, Jayarāśi Bhaṭṭa, and Shriharsha. In Greece philosophers as early as Xenophanes (c. 570 – c. 475 BCE) expressed skeptical views, as did Democritus and a number of Sophists. Gorgias, for example, reputedly argued that nothing exists, that even if there were something we could not know it, and that even if we could know it we could not communicate it. The Heraclitean philosopher Cratylus refused to discuss anything and would merely wriggle his finger, claiming that communication is impossible since meanings are constantly changing. Socrates also had skeptical tendencies, claiming to know nothing worthwhile. There were two major schools of skepticism in the ancient Greek and Roman world. The first was Pyrrhonism, founded by Pyrrho of Elis (c. 360–270 BCE). The second was Academic Skepticism,