Siddhanta, in the context of Vaisheshika philosophy, refers to the pursuit of establishing the ultimate truth of reality. It aims to provide a comprehensive understanding of the fundamental principles that govern the universe and the nature of existence.

In Vaisheshika philosophy, the three main categories of existence are Substance (dravya), Quality (guna), and Action (karma). Substances are the fundamental building blocks of the universe, while qualities are the properties that substances possess. Actions are the processes or changes that substances undergo.

In Siddhanta, perception is considered to be the primary means of acquiring knowledge about the world. It is through perception that we gain information about the various objects and phenomena that exist in the universe.

Siddhanta emphasizes the importance of examining the logical consistency of arguments in order to distinguish between valid and invalid knowledge. It employs various logical principles and syllogistic reasoning to evaluate the validity of claims and propositions.

The ultimate goal of a Siddhanta is to acquire comprehensive knowledge of the universe and its underlying principles. This knowledge is sought not for personal gain or worldly desires, but for the sake of understanding the true nature of reality.

Siddhanta addresses the problem of change by explaining it as the rearrangement of eternal atoms. According to this view, the fundamental constituents of the universe are eternal and unchanging, and change occurs as these atoms combine and separate in different configurations.

The concept of 'dravya' in Siddhanta refers to all objects and substances that exist in the universe. It encompasses both material and non-material entities, including atoms, molecules, minds, and consciousness.

Siddhanta posits that substance is the substratum for qualities, while qualities are inherent in substance. This means that substances provide the foundation for qualities to exist, and qualities cannot exist independently of substances.

Inference is recognized as a valid means of acquiring knowledge in Siddhanta. It allows us to gain information about objects and phenomena that are not directly accessible through perception. Inference involves drawing conclusions based on evidence and logical reasoning.

Siddhanta adopts the position that universals are inherent in particulars. This means that universals, such as 'cowness' or 'humanity', are not separate entities but rather exist within and are exemplified by individual particulars, such as cows or humans.

The concept of 'abhava' in Siddhanta refers to the absence or negation of something. It encompasses various types of absence, including the absence of an object, the absence of a quality, or the absence of a relationship between two entities.

Siddhanta posits that cause is the antecedent of effect, while effect is the consequent. This means that cause precedes effect in time and is responsible for bringing about the effect.

Testimony is recognized as a valid means of acquiring knowledge in Siddhanta. It involves accepting information from reliable sources, such as experts, authorities, or sacred texts. Testimony is considered to be a reliable source of knowledge as long as it is consistent with other sources of knowledge and does not contradict logical reasoning.

Siddhanta addresses the problem of evil by arguing that evil is a product of human ignorance and desire. It posits that evil arises when individuals act out of ignorance, misunderstanding the true nature of reality, or when they are driven by selfish desires and attachments.

The ultimate goal of a Siddhanta, according to the Vaisheshika philosophy, is to acquire comprehensive knowledge of the universe. This knowledge is sought not for personal gain or worldly desires, but for the sake of understanding the true nature of reality.