Functionalism affirms that every substance is material in nature because of it being conceivable. This also allows that the mind, the brain, and the identity of a thing or a sentient being are also material. However, functionalism falls short of defining its claim on concepts and thoughts that are partially considered, in the sense, they are abstract and do not have any defined way of manifestation.
Concrete entities, as per functionalism, are conceivable, but it is rarely possible to conceive abstract entities that are just ideas and immaterial in nature. Bodily pain is realised only by the mind perceiving the pain to the part where it is directed, but the realisation process of the pain is unrecognisable, hence functionalists’ claim of its materiality is distorted. The same is the case in computers workings of the hardware and software, where the internal software workings are not perceived at all. Functionalism and materialism, though more or less same in their claims of objective bodies and their conception, they differ slightly in their intrinsic workings and the claim of objective materials.
Radical interpretation claims that the existence of a mind is presupposed to the pre-existence of a prior mind and that further to its prior mind, and so on, leading to a continuous battle with historical origins of the mind and its power to think. Propositions made about an abstract feeling to arrive are without its basis in terms of its interpretation, and hence possibly out of the purview of the exact interpretation required to decipher its contents and intents. However, the t-theories manages to narrow the interpretation distance between what is uttered and what is ideally interpreted, it remains refutable and vulnerable, because the truth conditions required for interpreting an uttered sentence are varied and not usually pre-acquired.
Even the I-theory which depends on the individual’s ability to interpret through identification of the primitive attitudes, beliefs, feelings, purposes, and thoughts of the utterer, fails to remain tenable. Decision theory, indeterminacy, and the omniscient interpreter also fail to come to a definitive conclusion about the definiteness of a particular interpretation. All these being solely dependent on the I-theory fails to complex nature of the ability and the efforts that goes to make a radical interpretation possible, which one is closest or identical to what the utterer expects his listeners to acquire.