रुद्र विष्णुप्रजानाथप्रमुखाः सर्वचेतनाः । स्वरसेनाहमित्याहुरिदमित्यपि च स्वतः ॥ २॥
The Consciousness is the principle entity amongst, Rüdra, Vishñu, and Prajänätha(Brahma).The Instinctual expression, in expressing the essence of the self, by thus having said here "I".
एवं समस्तजन्तूनामनुभूतिर्व्यवस्थिता ।
भ्रान्ता अपि न कुर्वन्ति विवादं चात्र सत्तमाः ॥ ५॥
And thus established as an experience in all living creatures, Not only the wise here but even the deluded too don't make any debate over it.
These two are the shlokas are from Skanda Purana's---Suta Gita's---Fifth chapter---आत्मस्वरूपकथनम्, through which we conclude, That there's no paradox that whether Ätmä exists or not, rather it's factual that it verily exists, It's the substantial verity of every sentient entity extant here in the world.
Swami Vidyaranya tirthagaru of Shringeri in his dřg-drishya viveka, avows that, such a person who says, I don't believe in Ätmä, is alike to the person who loudly says that, I don't have a tongue. This is the attitude beholded by every Vedantist or even other philosophers whether it's from the rest five orthodoxical Vedic schools of philosophy and even the heterodoxical Jain school of philosophy.
But whatever that is experienced is an Object, while Ätmä is the one who experiences. Objects are said to be ज्ञेय-Jnèya(that which can be known) while Ätmä is ज्ञाता-Jnätä(that which knows), Objects are said to be कृति-krüti(That established by actions being done), while Ätmä is कर्ता-kartä(That which is doer of actioms), Objects are said to be दृष्ट-drishta(That which seen or percieved), while Ätmä is दृष्टा-drishtä(That which is the seer or perceiver). By these concepts of discerning what is Ätmä, and what is Object.