Nyaya philosophy is one of the six classical schools of Hindu philosophy, focused on logic and epistemology. It is based on the belief that true knowledge leads to liberation and understanding the principles of logic is essential in attaining this knowledge. The main principles of Nyaya philosophy can be summarized as follows:

1. Pramana (Means of Knowledge): The Nyaya school recognizes four main means of knowledge – perception, inference, comparison, and testimony. Perception refers to direct sensory experience, while inference is the process of arriving at a conclusion based on reasoning and evidence. Comparison involves understanding the similarities and differences between objects, and testimony is accepting knowledge from reliable sources.

2. Prameya (Objects of Knowledge): According to Nyaya philosophy, there are six objects of knowledge – substance, quality, action, generality, particularity, and inherence. These objects are considered to be the building blocks of the universe and understanding them is crucial in attaining true knowledge.

3. Pramana Parityakta (Means of Knowledge Rejected): Nyaya philosophy also recognizes three means of knowledge that are rejected – error, doubt, and verbal testimony. Error refers to false knowledge based on incorrect perception or inference, while doubt is the lack of certainty in one's knowledge. Verbal testimony is rejected if it contradicts direct perception or inference.

4. Pratyaksa (Perception): Perception is considered the most reliable means of knowledge in Nyaya philosophy. It is divided into two types – direct perception (pratyaksa) and indirect perception (paroksa). Direct perception refers to the immediate knowledge gained through the senses, while indirect perception refers to knowledge gained through inference or testimony.

5. Anumana (Inference): Inference is an important aspect of Nyaya philosophy, and it is based on the principle of cause and effect. It involves observing a particular effect and inferring the cause behind it. Inference is considered a reliable means of knowledge when it is based on sound reasoning and evidence.

6. Upamana (Comparison): Comparison or analogy is another means of knowledge recognized by Nyaya philosophy. It involves understanding the similarities and differences between objects and using this knowledge to gain a deeper understanding of them.

7. Sabda (Testimony): Testimony or verbal testimony is the last means of knowledge recognized by Nyaya philosophy. It refers to accepting knowledge from reliable sources, such as scriptures or trustworthy individuals.

In conclusion, Nyaya philosophy is based on the principles of logical reasoning and understanding the means of knowledge. It emphasizes the importance of gaining true knowledge and using it to attain liberation. By following these principles, one can gain a deeper understanding of the universe and the self.