@Pandya There are no contradictions between Tantras and Upanishads. At least if Shakta Tantras are concerned. All Bhedavada doctrines are condemned in Shakta Darsanas. Advaita is the philosophy of the Shakta Tantras too.
@Pandya Don't consider words of @Rakesh as words of Agamic people. :P He comes with his "logic" everywhere. You can ask Rickross if you want to know about Agamas.
@Pandya No there is no reasons to believe so. In fact several Tantra acharyas consider the knowledge described in the Tantras and the one described in Upanishads as the same. The philosophy of Shaktism is pure Advaita.
@Rickross See there are three concepts I found around me:
1. Consider Samhita + Brahmanas (including Aranyaka & Upanishads ) as Veda/Shruti though only Samhita is heard by ancient Rishis in Tapasya i,e Apaurusheya -- Which I have been following
2. Only consider Samhita as Veda/Sruti -- which is introduced by Arya Samaj / Dayananda Sarasvati and I don't endorse it.
@Pandya Even Rishi Auronindo believed that Samhita is only Vedas. Otherwise we cud have linked to a Upanishad verse by notations like RIg Veda x.y.z but we don't do it right?
3. Samhita & Brahmanas (including Aranyaka & Upanishads) are Apaurusheya, Shruti & Veda!! I recently found some sustainable arguments from Purva Mimansa -- which I'm unclear about.
@Pandya Yes not only Upanishads. What about Smritis Puranas etc? Suppose there is conflict between Darsana Sutras and Puranas how to resolve the issue then?
I think Puranas will override the Darsanas.
Sruti overirides Smriti, Smritis override Puranas and so on..In this list i think the Darsana Sutras will come at the last. @Pandya