information:classification
Legacy

Under Philip II, Spain reached the peak of its power. However, in spite of the great and increasing quantities of gold and silver flowing into his coffers from the American mines, the riches of the Portuguese spice trade, and the enthusiastic support of the Habsburg dominions for the Counter-Reformation, he would never succeed in suppressing Protestantism or defeating the Dutch rebellion. Early in his reign, the Dutch might have laid down their weapons if he had desisted in trying to suppress Protestantism, but his devotion to Catholicism would not permit him to do so. He was a devout Catholic and exhibited the typical 16th century antipathy for religious heterodoxy; he said, "Before suffering the slightest damage to religion in the service of God, I would lose all of my estates and a hundred lives, if I had them, because I do not wish nor do I desire to be the ruler of heretics."

As he strove to enforce Catholic orthodoxy through an intensification of the Inquisition, students were barred from studying elsewhere, and books printed by Spaniards outside the kingdom were banned. In addition to the banning of books, Philip II authorized the burning of at least 70,000 volumes. Even a highly respected churchman like Archbishop Bartolome Carranza of Toledo was jailed by the Inquisition for 17 years, for publishing ideas that seemed sympathetic in some degree with Protestantism. Such strict enforcement of orthodox belief was successful, and Spain avoided the religiously inspired strife tearing apart other European dominions.

Although he was deeply dedicated to rooting out heretical titles, he collected forbidden books for his own royal library at the El Escorial. His library contained 40,000 volumes (1,800 of which were Arabic titles) and several thousand manuscripts. The banned books were protected in a room on an upper floor of the library. He was passionate about rare books he personally collected from far and wide and researched and recorded information about previous owners.

The School of Salamanca flourished under his reign. Martín de Azpilcueta, highly honoured at Rome by several popes and looked on as an oracle of learning, published his Manuale sive Enchiridion Confessariorum et Poenitentium (Rome, 1568), long a classical text in the schools and in ecclesiastical practice.

Francisco Suárez, generally regarded as the greatest scholastic after Thomas Aquinas and regarded during his lifetime as being the greatest living philosopher and theologian, was writing and lecturing, not only in Spain but also in Rome (1580–1585), where Pope Gregory XIII attended the first lecture that he gave. Luis de Molina published his De liberi arbitrii cum gratiae donis, divina praescientia, praedestinatione et reprobatione concordia (1588), wherein he put forth the doctrine attempting to reconcile the omniscience of God with human free will that came to be known as Molinism, thereby contributing to what was one of the most important intellectual debates of the time; Molinism became the de facto Jesuit doctrine on these matters, and is still advocated today by William Lane Craig and Alvin Plantinga, among others.

Because Philip II was the most powerful European monarch in an era of war and religious conflict, evaluating both his reign and the man himself has become a controversial historical subject. Even before his death in 1598, his supporters had started presenting him as an archetypical gentleman, full of piety and Christian virtues, whereas his enemies depicted him as a fanatical and despotic monster, responsible for inhuman cruelties and barbarism. This dichotomy, further developed into the so-called Spanish Black Legend and White Legend, was helped by King Philip himself. Philip prohibited any biographical account of his life to be published while he was alive, and he ordered that all his private correspondence be burned shortly before he died. Moreover, Philip did nothing to defend himself after being betrayed by his ambitious secretary Antonio Pérez, who published incredible calumnies against his former master; this allowed Pérez's tales to spread all around Europe unchallenged. That way, the popular image of the King that survives to today was created on the eve of his death, at a time when many European princes and religious leaders were turned against Spain as a pillar of the Counter-Reformation. This means that many histories depict Philip from deeply prejudiced points of view, usually negative.

However, some historians classify this anti-Spanish analysis as part of the Black Legend. In a more recent example of popular culture, Philip II's portrayal in Fire Over England (1937) is not entirely unsympathetic; he is shown as a very hardworking, intelligent, religious, somewhat paranoid ruler whose prime concern is his country, but who had no understanding of the English, despite his former co-monarchy there.

Even in countries that remained Catholic, primarily France and the Italian states, fear and envy of Spanish success and domination created a wide receptiveness for the worst possible descriptions of Philip II. Although some efforts have been made to separate legend from reality, that task has proved extremely difficult, since many prejudices are rooted in the cultural heritage of European countries. Spanish-speaking historians tend to assess his political and military achievements, sometimes deliberately avoiding issues such as the King's inflexible Catholicism. English-speaking historians tend to show Philip II as a fanatical, despotical, criminal, imperialist monster, minimising his military victories (Battle of Lepanto, Battle of Saint Quentin, etc.) to mere anecdotes, and magnifying his defeats (namely the Armada) even though at the time those defeats did not result in great political or military changes in the balance of power in Europe. Moreover, it has been noted that objectively assessing Philip's reign would necessitate a re-analysis of the reign of his greatest opponents, namely England's Queen Elizabeth I and the Dutch William the Silent, who are popularly regarded as great heroes in their home nations; if Philip II is to be shown to the English or Dutch public in a more favourable light, Elizabeth and William would lose their cold-blooded, fanatical enemy, thus decreasing their own patriotic accomplishments.

He ended French Valois ambitions in Italy and brought about the Habsburg ascendency in Europe. He secured the Portuguese kingdom and empire. He succeeded in increasing the importation of silver in the face of English, Dutch, and French privateers, overcoming multiple financial crises and consolidating Spain's overseas empire. Although clashes would be ongoing, he ended the major threat posed to Europe by the Ottoman Navy.

Historian Geoffrey Parker offers a management-psychological explanation, as summarized by Tonio Andrade and William Reger:

One might have expected that Philip—being a dedicated, persistent, and hard-working man, and being the head of Western Europe's wealthiest and largest empire—would have succeeded in his aims. He didn't. His endeavors were doomed by his own character, or at least that's how Parker sees it. Drawing on studies in management science and organizational psychology, Parker argues that a successful manager of a large organization must keep attention on the big picture, must have a good strategy for dealing with copious information, must know how to delegate, and must be flexible. Philip failed on all counts. He was a micromanager who got bogged down in details, refusing to delegate and trying to read every dispatch that came to his desk. He obsessed and dithered, so that by the time his decisions were made and his orders reached the men meant to carry them out, the situation on the ground had changed. Philip was also inflexible, unwilling to abandon ineffective policies. Most pernicious of all was Philip's tendency toward messianic thinking, a belief that he was doing God's work and that heaven would support him with miracles.