Step 1: Understanding the Concept of Self.
In Buddhist philosophy, the self is not considered to be a permanent or independent entity. Instead, it is viewed as a potentiality or a stream of consciousness, which Buddha described as impermanent and dependent on conditions.
Step 2: Analyzing the Options.
- 1. Kumarila: Kumarila was an advocate of the Mimamsa school of philosophy and believed in the existence of the self, but he did not describe it as mere potency of knowledge.
- 2. Buddha: This is correct. Buddha viewed the self as an impermanent phenomenon and not an independent essence. The idea of self as a potency aligns with Buddhist teachings.
- 3. Patanjali: Patanjali is known for his Yoga Sutras, which discuss the nature of consciousness and self, but he did not describe the self as merely the potency of knowledge.
- 4. Sankaracharya: Sankaracharya believed in Advaita Vedanta, where the self (Atman) is considered the ultimate reality, not merely a potentiality.
Step 3: Conclusion.
The correct answer is 2. Buddha.
Final Answer:
\[
\boxed{\text{The correct answer is 2. Buddha.}}
\]