ॐ गुरुपरमात्मने नमः

3.56.2   आत्मनः जननाभावः

“नाहं परिणाम आकारो वा, न वा तन्मम” इति कथं ज्ञेयम्?

आत्मनः जननाभ्युपगमे तस्य अनित्यत्वप्रसङ्गः। तन्मतं मीमांसकादयः परलोकवादिनो व्याहरन्ति। तदसङ्गतम्। आत्मनो यदि उत्पत्तिः, तन्नाशावन्। ततः कृतनाशाकृताभ्यागमप्रसङ्गः। पूर्वजन्माचरितशुभकर्म अन्तरा सुखभोगः, इहजन्मनि कृतस्य कर्मणः नाशश्च। इमौ दोषौ अपरिहार्यौ।

ātma is not born

How do I know that I am not subject to birth or death, and they are not mine?

If we accept that ātma has a beginning, it will be non-eternal. This is the view of mīmāmsakās and those who accept para lokas. This is not tenable. If it has a beginning, it will have an end. This will result in the doshas known as (1) kr̥ta-nāśa and (2) akr̥ta-abhyāgama. i.e. (1) the experience of sukha without having performed good karmas in the past; and (2) the destruction of karma performed now. These logical doṣas cannot be refuted.