•Habermas’ weak naturalism is an ontological thesis (i.e. it presupposes a certain conception of ‘what is the case’). However it is not ontological in the sense that it does not aim to describe immutable and universal essences of things.
The above requires two things:
1)It requires an explanation of how the “realm of causality” and the “space of reason” (freedom) are related, in a determinate way. Or in other words, its viability hinges on an explanation of the possibility of the emergence of spontaneity (freedom) and consequently ‘space of reason’ without recourse to supernaturalism of any kind. Thus it requires the rejection of both the Christian transcendent God (for example) and Kant’s two-world solution. This is the consequence of the commitment to naturalism understood in a broad sense as a thesis that rejects all kinds of supernaturalisms.
2) It needs to be shown how the ‘realm of causality’ and the ‘realm of reason’ despite being primordially related and situated on the same natural plain are mutually exclusive. This is another way of saying that we need to maintain Kant’s distinction between nature and reason however without espousing his ontological dualism. This is Habermas’ preservation of the ‘essence’ of idealistic insights about reason within an overall naturalism/materalism.
1a) The above (1), requires developing a concept of freedom that does not treat ‘limits’ as opposite of freedom but rather as the conditions of the possibility of freedom, this entails rejection of a merely negative conception of freedom as the absence of limitations. This is important because if we keep working with a concept of spontaneity defined as “unconditioned condition” there is no way we can avoid either reverting back to Kantian dualism (by positing the realm of pure intelligibility) or alternatively opting for what McDowell has called ‘bald naturalism’.
1b) Evidently the above (1a) presupposes detranscendentalisation of the Kantian subject.
1c) The above (1a) only shows the possibility of freedom (space of freedom) emerging from within ‘nature’ it does not show its actuality.
1d) A conception of freedom explained (1a) is an ontological/descriptive conception of freedom.
2a) The (2) requires adopting methodological dualism between the participant perspective and the observer’s perspective: “As soon as we act out of . . . “with an orientation to reaching mutual understanding,” we cannot at the same time act from the objectivating perspective of an observer.” (TJ: 97).
2b) From within the participant perspective by analysing the process of reaching understanding about something in the world with the alter, it can be shown that:
2c) There exists a causality quite unlike natural causality which may be termed as causality of reason (following Kant) and which does not partake in the causality of nature. The participants in communicative action are affected by this force without force and are immune from natural causality as long as they are with bound within the participant perspective.
2d) From within the participant perspective it can also be shown how transcendence from within and into this world is possible.
The above analysis requires further presupposition that:
3)“the biological endowment and the cultural way of life Homo sapiens have a “natural” origin and can in principle be explained in terms of evolutionary theory.” (TJ: 28).
3a)Thus it presupposes continuity between culture and nature without obliterating distinction between them (ibid.).
4) Habermas’ weak naturalism as described above is an ontological/descriptive conception and though is the precondition of Habermas’ justification of modernity it is not in itself a prescriptive conception. It is in principle compatible with views quite different in their prescriptive agendas.