18 ideas
| 19504 | My modus ponens might be your modus tollens [Pritchard,D] |
| Full Idea: One philosopher's modus ponens is another philosopher's modus tollens. | |
| From: Duncan Pritchard (Epistemological Disjunctivism [2012], 3.§2) | |
| A reaction: [Anyone know the originator of this nice thought?] You say A is true, and A proves B, so B is true. I reply that if A proves something as daft as B, then so much the worse for A. Ain't it the truth? |
| 13768 | Validity can preserve certainty in mathematics, but conditionals about contingents are another matter [Edgington] |
| Full Idea: If your interest in logic is confined to applications to mathematics or other a priori matters, it is fine for validity to preserve certainty, ..but if you use conditionals when arguing about contingent matters, then great caution will be required. | |
| From: Dorothy Edgington (Conditionals [2001], 17.2.1) |
| 13770 | There are many different conditional mental states, and different conditional speech acts [Edgington] |
| Full Idea: As well as conditional beliefs, there are conditional desires, hopes, fears etc. As well as conditional statements, there are conditional commands, questions, offers, promises, bets etc. | |
| From: Dorothy Edgington (Conditionals [2001], 17.3.4) |
| 13764 | Are conditionals truth-functional - do the truth values of A and B determine the truth value of 'If A, B'? [Edgington] |
| Full Idea: Are conditionals truth-functional - do the truth values of A and B determine the truth value of 'If A, B'? Are they non-truth-functional, like 'because' or 'before'? Do the values of A and B, in some cases, leave open the value of 'If A,B'? | |
| From: Dorothy Edgington (Conditionals [2001], 17.1) | |
| A reaction: I would say they are not truth-functional, because the 'if' asserts some further dependency relation that goes beyond the truth or falsity of A and B. Logical ifs, causal ifs, psychological ifs... The material conditional ⊃ is truth-functional. |
| 13765 | 'If A,B' must entail ¬(A & ¬B); otherwise we could have A true, B false, and If A,B true, invalidating modus ponens [Edgington] |
| Full Idea: If it were possible to have A true, B false, and If A,B true, it would be unsafe to infer B from A and If A,B: modus ponens would thus be invalid. Hence 'If A,B' must entail ¬(A & ¬B). | |
| From: Dorothy Edgington (Conditionals [2001], 17.1) | |
| A reaction: This is a firm defence of part of the truth-functional view of conditionals, and seems unassailable. The other parts of the truth table are open to question, though, if A is false, or they are both true. |
| 19503 | An improbable lottery win can occur in a nearby possible world [Pritchard,D] |
| Full Idea: Low probability events such as lottery wins can occur in nearby possible worlds. | |
| From: Duncan Pritchard (Epistemological Disjunctivism [2012], 2.n2) | |
| A reaction: This seems to ruin any chance of mapping probabilities and counterfactuals in the neat model of nested possible worlds (like an onion). [Lewis must have thought of this, surely? - postcards, please] |
| 19505 | Moore begs the question, or just offers another view, or uses 'know' wrongly [Pritchard,D, by PG] |
| Full Idea: The three main objections to Moore's common-sense refutation of scepticism is that it either begs the question, or it just offers a rival view instead of a refutation, or it uses 'know' in a conversationally inappropriate way. | |
| From: report of Duncan Pritchard (Epistemological Disjunctivism [2012], 3.§2) by PG - Db (ideas) | |
| A reaction: [I deserve applause for summarising two pages of Pritchard's wordy stuff so neatly] |
| 19499 | We can have evidence for seeing a zebra, but no evidence for what is entailed by that [Pritchard,D] |
| Full Idea: The closure principle forces us to regard Zula as knowing that what she is looking at is not a cleverly disguised mule, and yet she doesn't appear to have any supporting evidence for this knowledge. | |
| From: Duncan Pritchard (Epistemological Disjunctivism [2012], 2.§3) | |
| A reaction: [Zula observes a zebra in the zoo] Entailment is a different type of justification from perception. If we add fallibilism to the mix, then fallibility can increase as we pursue a string of entailments. But proper logic, of course, should not be fallible. |
| 19500 | Favouring: an entailment will give better support for the first belief than reason to deny the second [Pritchard,D] |
| Full Idea: The Favouring Principle says that if S knows two things, and that the first entails the second, then S has better evidence in support of her belief in the first than she has for denying the second. | |
| From: Duncan Pritchard (Epistemological Disjunctivism [2012], 2.§3) | |
| A reaction: [his version is full of Greek letters, but who wants that stuff?] Pritchard concludes that if you believe in the closure principle then you should deny the favouring principle. |
| 19502 | Maybe knowledge just needs relevant discriminations among contrasting cases [Pritchard,D] |
| Full Idea: According to the 'contrastivist' proposal knowledge is to be understood as essentially involving discrimination, such that knowing a proposition boils down to having the relevant discriminatory capacities. | |
| From: Duncan Pritchard (Epistemological Disjunctivism [2012], 2.§6) | |
| A reaction: Pritchard says this isn't enough, and we must also to be aware of supporting favouring evidence. I would focus on the concept of coherence, even for simple perceptual knowledge. If I see a hawk in England, that's fine. What if I 'see' a vulture? |
| 19498 | Epistemic internalism usually says justification must be accessible by reflection [Pritchard,D] |
| Full Idea: Typically, internal epistemic conditions are characterised in terms of a reflective access requirement. | |
| From: Duncan Pritchard (Epistemological Disjunctivism [2012], 1.§6) | |
| A reaction: If your justification is straightforwardly visual, it is unclear what the difference would be between seeing the thing and having reflective access to the seeing. |
| 19506 | Externalism is better than internalism in dealing with radical scepticism [Pritchard,D] |
| Full Idea: Standard epistemic internalism faces an uphill struggle when it comes to dealing with radical scepticism, which points in favour of epistemic externalist neo-Mooreanism. | |
| From: Duncan Pritchard (Epistemological Disjunctivism [2012], 3.§3) | |
| A reaction: I incline towards internalism. I deal with scepticism by being a fallibilist, and adding 'but you never know' to every knowledge claim, and then getting on with life. |
| 19496 | Disjunctivism says perceptual justification must be both factual and known by the agent [Pritchard,D] |
| Full Idea: Slogan for disjunctivism: perceptual knowledge is paradigmatically constituted by a true belief whose epistemic support is both factive (i.e. it entails the truth of the propositions believed) and reflectively accessible to the agent. | |
| From: Duncan Pritchard (Epistemological Disjunctivism [2012], Intro) | |
| A reaction: I'm not a fan of externalism, but it could be that the factive bit achieves the knowledge, and then being able to use and answer for that knowledge may just be a bonus, and not an essential ingredient. |
| 19497 | Metaphysical disjunctivism says normal perceptions and hallucinations are different experiences [Pritchard,D] |
| Full Idea: Metaphysical disjunctivists hold that veridical perceptual experiences are not essentially the same as the experiences involved in corresponding cases involving illusion and (especially) hallucination. | |
| From: Duncan Pritchard (Epistemological Disjunctivism [2012], 1.§4) | |
| A reaction: Metaphysical disjunctivism concerns what the experiences are; epistemological justification concerns the criteria of justification. I think. I wish Pritchard would spell things out more clearly. Indeed, I wish all philosophers would. |
| 19495 | Epistemic externalism struggles to capture the idea of epistemic responsibility [Pritchard,D] |
| Full Idea: A fundamental difficulty for epistemic externalist positions is that it is hard on this view to capture any adequate notion of epistemic responsibility. | |
| From: Duncan Pritchard (Epistemological Disjunctivism [2012], Intro) | |
| A reaction: He never explains the 'responsibility', but I presume that would be like an expert witness in court, vouching for their knowledge. |
| 19501 | We assess error against background knowledge, but that is just what radical scepticism challenges [Pritchard,D] |
| Full Idea: When faced with an error-possibility we can appeal to background knowledge, as long as the error-possibility does not call into question this background knowledge. The same is not true when we focus on the radical sceptical hypothesis. | |
| From: Duncan Pritchard (Epistemological Disjunctivism [2012], 2.§5) | |
| A reaction: [reworded] Doubting everything simultaneously just looks like a mad project. If you doubt linguistic meaning, you can't even express your doubts. |
| 19507 | Radical scepticism is merely raised, and is not a response to worrying evidence [Pritchard,D] |
| Full Idea: Crucially, radical sceptical error-possibilities are never epistemically motivated, but are instead merely raised. | |
| From: Duncan Pritchard (Epistemological Disjunctivism [2012], 3.§5) | |
| A reaction: In 'The Matrix' someone sees a glitch in the software (a cat crossing a passageway), and that would have to be taken seriously. Otherwise it is a nice strategy to ask why the sceptic is raising this bizzare possibility, without evidence. |
| 6175 | External identification doesn't mean external location, as with sunburn [Davidson, by Rowlands] |
| Full Idea: Davidson observes that the inference from a thought being identified by a relation to something outside the head does not entail that the thought is not wholly in the head, just as sunburn is identified by external factors, but is still in the skin. | |
| From: report of Donald Davidson (Knowing One's Own Mind [1987]) by Mark Rowlands - Externalism Ch.8 | |
| A reaction: Rowlands (an externalist) agrees, and this strikes me as correct, and it needs to be one of the fixed points in any assessment of externalism. |