Aletheia   is Greek for ‘truth; truthfulness, frankness, sincerity’. Alethes is ‘true; sincere, frank; real, actual’. There is also a verb, aletheuein, ‘to speak truly, etc’ (cf. GA19  , 21ff.). The words are related to lanthanein, with an older form lethein, ‘to escape notice, be unseen, unnoticed’, and lethe  , ‘forgetting, forgetfulness’. An initial a- in Greek is often privative, like the Latin in- or the Germanic un. (The ‘privative alpha’ occurs in many Greek-derived words: ‘anonymous’, ‘atheism’, etc.) Alethes, aletheia are generally accepted to be a-lethes, a-letheia, that which is ‘not   hidden or forgotten’, or he who ‘does not hide or forget’.

We reach the ‘essence of truth’, the ‘openness of the open’, from two directions: from ‘reflection on the ground of the possibility of correctness (adaequatio  )’ and from ‘recollection of the beginning (aletheia)’ (GA65  , 338). The first procedure is characteristic of SZ   and early lectures, the second of later works. But early on Heidegger says that aletheuein is ‘to take out of hiddenness [Verborgenheit  ], to uncover [entdecken  ]’ (GA22  , 25. Cf.GA21  , 131; SZ, 33, 219); aletheia is ‘uncovering’ (GA21, 162); and alethes is ‘unhidden [Unverborgen(es)]’ (SZ, 33, 219). This has three implications: 1. Truth is not confined to explicit assertions and discrete mental, primarily theoretical, attitudes such as judgements, beliefs and representations. The world as a whole, not just entities within it, is unhidden - unhidden as much by moods as by understanding. 2. Truth is primarily a feature of reality - beings, being and world - not of thoughts and utterances. Beings, etc. are, of course, unhidden to we, and we disclose them. Heidegger later coins entbergen  ; Entbergung; Eniborgenheit, ‘to unconceal; -ing; -ment’, since unlike unverborgen, they can have an active sense: ‘alethes means: 1. unconcealed [entborgen], said of beings, 2. grasping the unconcealed as such, ie. being unconcealing’ (GAXXXI, 91). But beings, etc. are genuinely unconcealed; they do not just agree with an assertion or representation. 3. Truth explicitly presupposes concealment or hiddenness. DASEIN   is in ‘untruth [Unwahrheit  ]’ as well as truth. In SZ (222, 256f.) this means that falling Dasein misinterprets things.

’Untruth’ is not plain ‘falsity’, nor is it ‘hiddenness’: it is ‘disguisedness [Verstelltheit  ]’ of the truth (GA31  , 91). Later, ‘untruth’ is still not ‘falsity’, but ‘hiding, concealing [Verbergung]’ (GA65, 362). What conceals is no longer man, but being. There are two types of unconcealing: (a) of the open, the world or beings as a whole; (b) of particular beings within this open space. The first type (a) involves concealment: everything was hidden before the open was established, and concealment persists in that the open reveals only certain aspects of reality, not its whole nature. The second type (b) involves a concealment that we overcome ‘partially and case by case’ (GA65, 338f.). Plato   errs in assimilating truth to light. We lose the idea   of hiddenness and thus the privative force of a-letheia: the light is constant - never switched on or off - and reveals everything there is to anyone who looks. We lose the idea of the open, which must persist throughout our unconcealing of beings: a single light cannot account both for the openness of the open and for the unconcealing of particular entities (GALXV, 339).

Plato’s error was fateful. He - not Aristotle  , who did his best to repair the damage (GA6  , 228) - initiated the decline of a-letheia into ‘correctness’ and truth as agreement (GA34  , 21ff; GA9  ). Aletheia was originally the basic feature of physis   (roughly, ‘nature’) and thus ‘essentially rejects any question about its relation to something else, such as thinking’ (GA65, 329). In Plato it ‘comes under the yoke of the idea’ (GA9). Idea, from the Greek idein, ‘to see’, refers, on Heidegger’s account, to the visual ‘aspect [Aussehen  ]’ of entities. The ascent of the prisoners out of the cave is a progressive ‘correction’ of their vision of this idea and the entity whose idea it is. Hence aletheia is no longer primarily a characteristic of beings: it is ‘yoked’ together with the soul, and consists in a homoiosis  , a ‘likeness’, between them. Homoiosis has since become adaequatio and then ‘agreement’, and since Descartes  , the relation between soul and beings has become the subject-object relation, mediated by a ‘representation’, the degenerate descendant of Plato’s idea. Truth becomes correctness, and its ‘elbow-room [Spielraum  ]’, the open, is neglected (GA65, 198, 329ff.).

Heidegger’s account was attacked by Friedlander, 221-229: 1. It is not certain that alethes comes from a- and lanthanein. 2. Even if it does, it hardly ever means ‘unhidden’ in Homer  , Hesiod   and later authors, but has three main senses: the correctness of speech and belief (epistemological); the reality of being (ontological); the genuineness, truthfulness and conscientiousness of an individual or character (’existential’). 3. These three aspects of aletheia are united in Plato. The ascent from the cave is an ascent of being, of knowledge and of existence. Heidegger misunderstands this. He assumes that if Plato regards truth as correctness of apprehension, he has jettisoned its other senses, while if another sense reappears, this is because Plato is indecisive and ‘ambiguous’. The three senses are fused together in Plato. 4. Interpreting truth as unhiddenness would not save it from modern subjectivity: unhiddenness must be unhiddenness to someone.

On 2 and 3 Friedlander is right. Heidegger accepts 2, and implicitly 3, in EPAD (77s/447). His attempts to find aletheia as ‘unhiddenness’ in Plato invariably fail. When Plato says that the things we ‘make’ by holding up a mirror are not beings tei aletheiai, and that the things painters make are not alethe (Republic, 596d,e), Heidegger takes him to mean that things in mirrors and in paintings are not ‘unhidden’. (He also says that to understand how we can be said to make things by holding up a mirror, we must take ‘making’ in a special ‘Greek sense’.) (GA6, 206ff.) But things are no more hidden in a mirror than in the flesh. Plato’s point is that things in a mirror are not real, not alethe in the ontological sense. It is also untrue that idea, and its near-synonym eidos  , ‘form’, mean ‘aspect, appearance’; the assumption that the Greeks, if no-one else, invariably used words in accordance with their etymological roots is groundless (cf.GA6, 200).

Heidegger’s interpretations of aletheia and of Plato are indefensible. It does not follow that Friedlander is right on 4. This neglects Heidegger’s distinction between the open and the unconcealing of particular beings, and also his belief that we are made, and revealed as, what we are by the opening of the open, not ready-made waiting for things to be unhidden to us. In the Kantian vocabulary rejected by Heidegger, Friedlander thinks in ‘empirical’ rather than ‘transcendental  ’ terms. Heidegger is far closer to Plato, properly interpreted, than he acknowledges. [Inwood  ]