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a. Sceptical Arguments

A range of long-standing sceptical arguments support the recognition that none of our beliefs can be certain. These include the ten modes of Pyrrhonism, which tell us why our senses do not necessarily give us correct information about objects. The dream, error and time-lapse arguments also cast doubt on sensory information, and the relativity of cultural background on our interpretation of it. The problem of induction undermines general claims and the infinite regress of explanation casts doubt even on a priori claims like those of mathematics. The relativity and vagueness of linguistic categories also provide arguments that our language cannot provide reliable representations of the world. These arguments together mean that the grounds for sceptical argument are over-determined, as only one of them has to succeed.

b. The Failure of Philosophical Arguments against Scepticism

A range of philosophers, including Descartes, Hume, Burnyeat, Moore and Wittgenstein, have made arguments that attempt to overcome or sideline scepticism. All of these arguments make assumptions that are both unnecessary and practically unhelpful. Embodied creatures cannot have access to the self-evident truths claimed by Descartes. The various empiricist attempts to sideline scepticism, on the other hand, all misinterpret it as implying definite claims of denial rather than a mere recognition of uncertainty. This recognition, far from being impractical, is of great practical value. The publicity or otherwise of the language used by sceptics, pace Wittgenstein, also make no difference to its uncertainty. We cannot dodge the recognition of basic uncertainty by redefining ‘certainty’ in terms of ordinary language.

c. Provisionality

The implication of scepticism is provisionality: holding beliefs lightly. Positively, this implies optionality, antifragility, and slow thinking (see IV.2). Being able to consider more possible options physiologically suggests that left hemisphere representation is more fully linked to new right hemisphere information. Negatively, provisionality is also the awareness of the limitations of metaphysical beliefs, so that we can avoid them. Metaphysical beliefs are threatened by scepticism because of their dogmatic justification and dualistic form, whereas provisional beliefs, with awareness of alternative possibilities, already take uncertainty into account and are not threatened by it. The distinction between metaphysical beliefs and provisional beliefs is a psychological one dependent on the state of mind in which the belief is held, rather than only the representational content of the belief.

d. Incrementality

Incrementality here is the quality of being a matter of degree, applied to justification. It does not imply relativity of value nor any implicit appeal to a whole truth. Provisional claims are also incremental ones, and metaphysical claims have the property of being absolute or non-incremental, whether they are positive or negative in form. Common metaphysical dualisms between absolutism and relativism, mind and body, ideal and real, freewill and determinism, or theism and atheism can all be resolved through incremental thinking: see 4.4 for more details.

e. Distinguishing Negative Metaphysics from Agnosticism

The denial of any claim needs to be carefully distinguished from the mere recognition of uncertainty about that claim. The denial of positive metaphysical claims produces opposing negative metaphysical claims, whilst the avoidance of metaphysics requires agnosticism about all such claims. As metaphysical claims are infinite in scope, they are beyond all justification through experience. Sceptical argument offers equal uncertainty in relation to both positive and negative claims of this kind. Agnosticism here is hard agnosticism, because it does not expect future evidence about the infinite, but rather accepts that embodiment excludes it. Such agnosticism does not fail to consider metaphysical options, but it does decisively reject them on practical grounds. It applies equally to both practically important and trivial metaphysical claims, even though the former are more worthy of our attention.

f. Against A Priori Arguments for Metaphysics

The kinds of argument likely to be used to defend metaphysics by analytic philosophers appeal to a priori reasoning. These are undermined by linguistic scepticism, because they assume linguistic categories that are absolutely consistent and have unambiguous boundaries. This is not the case when meaning is recognised to be embodied, and the appeal to purely hypothetical definitions of terms is ad hoc, completely disconnected from experience. Even a=a is not a certainty in the context of experience, where the meaning of ‘a’ may shift organically at each moment. Kantian style a priori categories also cannot be shown to be absolutely universal. None of this prevents mathematics, logic or Kantian categories from being useful, as long as they are recognised as framed by uncertainty.

g. Against Revelatory Metaphysics

A theological way of trying to support metaphysics is through divine revelation. This requires absolute authority to be attributed to the scripture or other source of revelation, even though these sources can also be interpreted as having only incremental credibility. The absolute nature of this appeal makes it incompatible with ‘reason’, or with religious experience, as the infinite cannot be known through the finite without losing its infiniteness. Theological defences of revelation tend to bring in a dogmatic assumption of the infinite justification of a finite source, as well as often circularly assuming a metaphysical basis to support metaphysical revelation.

h. Sceptical Slippage and Modern Forms of Negative Metaphysics

Sceptical slippage is the tendency for agnostic arguments offering uncertainty to slip into denial and negative metaphysics. Atheism, relativism and naturalism are common modern positions that are due to this tendency. This slippage may happen because of the difficulty of understanding agnostic alternatives, the greater ease with which negative metaphysical positions can unite a group, and the representational assumption that language gets its meaning from a relationship with a ‘real world’ in which things can only exist or not exist. These factors create unholy alliances of dualists from both sides against anyone who challenges their framing. The sceptical slippage problem has constantly undermined reform movements which oppose old ‘truths’ only to create new opposing ones.

i. Against the Fact-Value Distinction

The fact-value distinction is founded on Hume’s logical point that values can’t be validly derived from facts: which works in its own abstract terms, but is completely disconnected from the human experience of inextricably connected facts and values. The distinction is thus another metaphysical assumption dependent on representationalism, in which represented facts are distinct from represented values, and this representation is assumed to match ‘reality’. This has been disastrous for ethics, making relativism the only alternative to dogmatic absolutism, and also for science, leading to the pretence that descriptions of facts can be value-free. However, value-laden facts and fact-laden values can be justified in the same ways, dependent on provisionality as well as coherence.

j. Metaphysical Assumptions about the Self

Beliefs about the self as a fixed entity like an object, whether such a self is affirmed or denied, are no more justifiable than other metaphysical beliefs. Kantian ideas about the self as a framing device are concerned with the conditions for experience, not the self we identify with. What is consistent in our experience is desire, which frames our beliefs, rather than beliefs themselves. The ego that makes us desire a self-identity is stable only in its changing wants, that are taken to be total at different times. That ego is based in left hemisphere experience, but the right provides us with the wider possibility of integrating those desires over time. We thus don’t have to either think of ourselves as fixed beyond the ego, nor to try to destroy the ego: even-handed scepticism can help us see the possibility of incrementally integrating the ego.