A misconception of the importance of language for philosophy is one factor that contributed to the devaluation of reason. Language is an important subject matter for philosophy. The investigation of language helps clarify the most important concepts. The language that a person speaks is essentially a tool of thought. It is particularly evident in philosophy, where thought is often related to language and expression comes much later.
Because language grows responding to the demands of though and communicating this thought, it will reflect characteristics of what it is trying to represent. However, Nagel states that we cannot account for reason by means of the naturalistic description of the practices of language, because the contemplation that language is a vehicle for reasoning do not admit of naturalistic or psychological or sociological analysis.
An important example of the attempt to explain the more fundamental in terms of the less fundamental is looking for the best explanation of logical necessity in the practices. Nagel criticizes this pattern of inversion by denying that the validity of the thoughts that language enables us to express depends on those conventions and usages. But he states that these cases of usage, as opposed to validity, people have to recognize that objectivity cannot outstrip community practice.
Wittgenstein’s conception of language incorporates a non-foundational epistemology which displays the notions of objectivity, sound judgment, and rationality, valid reasoning, as grounded in consensus–theoretical in the first instance, but ultimately practical. The trouble is that some of his most frequently quoted remarks seem to encourage us to go on beyond the point at which he maintains there is nothing more to be said; and we would have to explain why that is a misunderstanding. This leaves Wittgenstein without a positive theory of meaning or entailment, but perhaps that is just as well, given much of what he says about the aim of philosophy. We can understand him to claim that a certain level of agreement in usage and in judgments is a necessary condition for meaning, and for the possibility of giving sense to the distinction between correct and incorrect, but that this cannot be turned into a sufficient condition, either a truth condition or an assertability condition.
Nagel says that most of the reasoning we engage in is not deductive, but empirical, moral, and more broadly practical. He goes on to say that simple arithmetical and logical thoughts are examples of reasoning if anything is and are the pervasive elements of the thought of anyone who can think at all. When we put simple logical and mathematical thoughts side by side with any other thoughts they remain subject to their own standards and cannot be made the object of an external, purely psychological evaluation. In logic, the object language cannot be left behind.
Descartes refuses to recognize an important priority in logic. He holds on to the notion that God could have made the eternal truths to arithmetic different. He believes that 2 + 3 could equal 4 when in common logic it clearly equals 5. He rests the weight of this possibility in the idea of God’s omnipotence and responsibility for everything, which is greater than his confidence in his judgments of arithmetical conceivability. It is impossible to argue this way, because this argument relies on judgments of what is and is not conceivable. There isn’t room for skepticism about basic logic, because there is no place to stand where we can formulate or think it without immediately contradicting ourselves by relying on it.
Impossible logical skepticism is different from the ordinary epistemological kind, because the latter depends on an unchallenged capacity to conceive of alternative possibilities and derive implications from them. But in skepticism about logic, we can never reach a point at which we have two possibilities with which all the evidence is compatible and between which it is therefore impossible to choose. That does not apply, of course, to all propositions of logic or arithmetic. It is possible for a mathematician to have a belief about a controversial proposition like the continuum hypothesis which he neither finds self-evident nor is able to establish by a proof whose elements are themselves self-evident.
Apart from Subjectivism, Evolution, and God, Nagel asks “What are the alternatives?” One possibility is that some things can’t be explained because they have to enter into every explanation. There are inevitably going to be limits on the closure achievable by turning our procedures of understanding on themselves. If that is so, then the outer boundaries of our understanding will always be reached in unqualified, objective reasoning about the real world rather than in the interpretation and expression of our own perspective–personal or social. To engage in such reasoning is to try to bring one’s individual thoughts under the control of a universal standard that prescribes to each person those beliefs, available from his point of view, which can form part of a consistent set of objective beliefs dispersed over all rational persons.
Nagel, Thomas. The Last Word. Oxford University. New York (1997) pg. 37-77