| 411 | If we succeed in speaking the truth, we cannot know we have done it [Xenophanes] |
| 1545 | Protagoras was the first to claim that there are two contradictory arguments about everything [Protagoras, by Diog. Laertius] |
| 578 | Cratylus decided speech was hopeless, and his only expression was the movement of a finger [Cratylus, by Aristotle] |
| 577 | Democritus says there is either no truth, or it is concealed from us [Democritus, by Aristotle] |
| 20895 | We actually know nothing, and opinions are mere flux [Democritus] |
| 1528 | We in fact know nothing, but we each restructure our reality with beliefs [Democritus] |
| 492 | It is obviously impossible to understand the reality of each thing [Democritus] |
| 515 | We know nothing in reality; for truth lies in an abyss [Democritus] |
| 13792 | There can't be any knowledge if things are constantly changing [Plato] |
| 3061 | Anaxarchus said that he was not even sure that he knew nothing [Anaxarchus, by Diog. Laertius] |
| 6593 | The Pyrrhonians attacked the dogmas of professors, not ordinary people [Pyrrho, by Fogelin] |
| 4549 | Epicurus denied knowledge in order to retain morality or hedonism as the highest values [Nietzsche on Epicurus] |
| 1870 | The basis of scepticism is the claim that every proposition has an equal opposing proposition [Sext.Empiricus] |
| 1819 | Scepticism has two dogmas: that nothing is definable, and every argument has an opposite argument [Diog. Laertius] |
| 6260 | Sceptics say there is truth, but no means of making or testing lasting judgements [Montaigne] |
| 6347 | Descartes can't begin again, because sceptics doubt cognitive processes as well as beliefs [Pollock/Cruz on Descartes] |
| 2251 | Even if my body and objects are imaginary, there may be simpler things which are true [Descartes] |
| 12949 | Light takes time to reach us, so objects we see may now not exist [Leibniz] |
| 2238 | Reason can never show that experiences are connected to external objects [Hume] |
| 2242 | Mitigated scepticism draws attention to the limitations of human reason, and encourages modesty [Hume] |
| 4708 | Kant thought he had refuted scepticism, but his critics say he is a sceptic, for rejecting reality [O'Grady on Kant] |
| 14872 | Our knowledge is illogical, because it rests on false identities between things [Nietzsche] |
| 14879 | The most extreme scepticism is when you even give up logic [Nietzsche] |
| 6591 | Doubts can't exist if they are inexpressible or unanswerable [Wittgenstein] |
| 8593 | Maybe billions of changeless years have elapsed since my last meal [Shoemaker] |
| 13314 | Protagoras says arguments on both sides are always equal [Kim, by Seneca] |
| 530 | There are two contradictory arguments about everything [Kim] |
| 8722 | No one knows anything, and no one is ever justified or reasonable [Unger] |
| 7413 | Without confidence in our beliefs, how should we actually live? [Tuck] |
| 3594 | Scepticism just reveals our limited ability to explain things [Williams,M] |
| 6071 | Scepticism about reality is possible because existence isn't part of appearances [McGinn] |
| 19501 | We assess error against background knowledge, but that is just what radical scepticism challenges [Pritchard,D] |
| 12401 | A toper who spies in the distance... [Sommers,W] |