Cartesian dualism relies upon two substances, body and mind, which are totally distinguished by their properties. While the characteristic nature of body is Extendedness, the mind is known with its capability of thinking.
So, Cartesian Dualism is founded on these two basic propositions:
1. All bodies are extended.
2. All minds are thinkable.
Abandoning the latter, the former (1) seems acceptable to all physicalists. But if so, then its contraposition might be true equally. In other words, physicalists should be agreed with this proposition too:
3. All non-extended are non-body
The question is how physicalists justify this proposition?
In other hand, the unavoidable consequence of this proposition (and its truth) is existence of a non-extended (entity) which isn't body, which isn't justifiable in reductive physicalism approach. So, considering this proposition that in reductive physicalism approach:
4. everything has identify with physics.
But, isn’t paradoxical acceptance of (3) and (4)...