Since time immemorial or since the creation of the cosmic manifestation, the conditioned souls have formed various parties of philosophical speculation, but this is not true of the devotees. Nondevotees have different ideas of creation, maintenance and annihilation, and therefore they are called vādīs and prativādīs — proponents and counterproponents. It is understood from the statement of Mahābhārata that there are many munis, or speculators:

All speculators must disagree with other speculators; otherwise, why should there be so many opposing parties concerned with ascertaining the supreme cause?

Philosophy means finding the ultimate cause. As Vedānta-sūtra very reasonably says, athāto brahma jijñāsā: human life is meant for understanding the ultimate cause. Devotees accept that the ultimate cause is Kṛṣṇa because this conclusion is supported by all Vedic literature and also by Kṛṣṇa Himself, who says, ahaṁ sarvasya prabhavaḥ: “I am the source of everything.” Devotees have no problem understanding the ultimate cause of everything, but nondevotees must face many opposing elements because everyone who wants to be a prominent philosopher invents his own way. In India there are many parties of philosophers, such as the dvaita-vādīs, advaita-vādīs, vaiśeṣikas, mīmāṁsakas, Māyāvādīs and svabhāva-vādīs, and each of them opposes the others. Similarly, in the Western countries there are also many philosophers with different views of creation, life, maintenance and annihilation. Thus it is undoubtedly a fact that there are countless philosophers throughout the world, each of them contradicting the others.

Now, one might ask why there are so many philosophers if the ultimate goal of philosophy is one. Undoubtedly the ultimate cause is one — the Supreme Brahman. As Arjuna told Kṛṣṇa in Bhagavad-gītā (10.12):

“You are the Supreme Brahman, the ultimate, the supreme abode and purifier, the Absolute Truth and the eternal divine person. You are the primal God, transcendental and original, and You are the unborn and all-pervading beauty.” Nondevotee speculators, however, do not accept an ultimate cause (sarva-kāraṇa-kāraṇam). Because they are ignorant and bewildered concerning the soul and its activities, even though some of them have a vague idea of the soul, many controversies arise, and the philosophical speculators can never reach a conclusion. All of these speculators are envious of the Supreme Personality of Godhead, and as Kṛṣṇa says in Bhagavad-gītā (16.19-20):

“Those who are envious and mischievous, who are the lowest among men, are cast by Me into the ocean of material existence, into various demoniac species of life. Attaining repeated birth among the species of demoniac life, such persons can never approach Me. Gradually they sink down to the most abominable type of existence.” Because of their envy of the Supreme Personality of Godhead, nondevotees are born in demoniac families life after life. They are great offenders, and because of their offenses the Supreme Lord keeps them always bewildered. Kurvanti caiṣāṁ muhur ātma-moham: the Lord, the Supreme Personality of Godhead, purposely keeps them in darkness (ātma-moham).

The great authority Parāśara, the father of Vyāsadeva, explains the Supreme Personality of Godhead thus:

The demoniac speculators cannot understand the transcendental qualities, form, pastimes, strength, knowledge and opulence of the Supreme Personality of Godhead, which are all free from material contamination (vinā heyair guṇādibhiḥ). These speculators are envious of the existence of the Lord. Jagad āhur anīśvaram: their conclusion is that the entire cosmic manifestation has no controller, but is just working naturally. Thus they are kept in constant darkness, birth after birth, and cannot understand the real cause of all causes. This is the reason why there are so many schools of philosophical speculation.