There is a longstanding tradition of thinking of acquaintance as a way of being cognitively related to what cannot be described, conveyed or expressed. (James, 1890: 221; von Helmholtz, 1868: 308–9; Russell, 1903: v; perhaps also Leibniz, 1682-4: 285; Kant, 1992: 105–6, 466, 569–70; cf. 1787: B14–5.)

However, in more recent philosophy, where acquaintance has been discussed in relation to singular thought and reference, mental content, perception and foundationalist epistemology (e.g. Evans, 1982; McDowell, 1998; Fumerton, 1995; Campbell, 2002; Knowles & Raleigh, 2019) there has been something of a de-centring of the topic of the ineffable. The notable exception is, of course, Jackson’s ‘Knowledge Argument’ and responses to it invoking ‘phenomenal properties’ or qualia with which we can be acquainted; but even here, it is rare for philosophers to enter into any sustained discussion of what it might mean to say that what Mary learns when she leaves her black-and-white room is 'ineffable'.

Outside of the philosophy of mind, there has been some recent work on the relationship between ineffability and acquaintance. For example, A.W. Moore has suggested that ineffable knowledge might best be conceived as non-propositional knowledge. In his work, he takes this non-propositional knowledge to be knowledge-how or a kind of practical understanding; but others (e.g. Jonas 2016: chs. 6 & 7) have suggested that it might be better to think of it as knowledge-of, i.e. acquaintance. However, as things stand, this possibility remains relatively under-explored.

The aim of this workshop, then, is to focus on the relationship between ineffability and acquaintance. Abstracts are welcome from any area of philosophy, but here are some potential topics of interest:

- The relationship between phenomenal concepts or properties and ineffable truths.

- The relationship between ineffable knowledge and non-propositional knowledge.

- Acquaintance as a – and perhaps the only – way of grasping Fregean senses (Makin, 2000), and/or as a way of grasping what is shown but cannot be said (e.g Morris & Dodd, 2007).

- Acquaintance and the Kantian thing in itself.

- Religious experience as (involving) acquaintance with an ineffable God or ineffable aspects of God, and the epistemic upshot of that.

- Epistemological roles for acquaintance in relation to the ineffable, especially extending the epistemological significance of acquaintance beyond its traditional role in foundationalist epistemology.

- Acquaintance, ineffability and transformative experience (as in Paul, 2014).

- The kinds of things with which acquaintance is (or is not) possible (facts, states of affairs, propositions, properties, universals, particulars, objects etc.), and perhaps the implications of that for knowledge of ineffable truths.

- The history of philosophical reflection on the relation between acquaintance and the ineffable.