| 2011 | Defeasibility Theory |
| 'Defeater-Defs' | p.162 | 19717 | Can a defeater itself be defeated? |
| Full Idea: Can the original justification of a belief be regained through a successful defeat of a defeater? | |||
| From: Thomas Grundmann (Defeasibility Theory [2011], 'Defeater-Defs') | |||
| A reaction: [Jäger 2005 addresses this] I would have thought the answer is yes. I aspire to coherent justifications, so I don't see justifications as a chain of defeat and counter-defeat, but as collective groups of support and challenge. |
| 'Defeaters' | p.160 | 19716 | Simple reliabilism can't cope with defeaters of reliably produced beliefs |
| Full Idea: An unmodified reliabilism does not accommodate defeaters, and surely there can be defeaters against reliably produced beliefs? | |||
| From: Thomas Grundmann (Defeasibility Theory [2011], 'Defeaters') | |||
| A reaction: [He cites Bonjour 1980] Reliabilism has plenty of problems anyway, since a generally reliable process can obviously occasionally produce a bad result. 20:20 vision is not perfect vision. Internalist seem to like defeaters. |
| 'How' | p.158 | 19715 | You can 'rebut' previous beliefs, 'undercut' the power of evidence, or 'reason-defeat' the truth |
| Full Idea: There are 'rebutting' defeaters against the truth of a previously justified belief, 'undercutting' defeaters against the power of the evidence, and 'reason-defeating' defeaters against the truth of the reason for the belief. | |||
| From: Thomas Grundmann (Defeasibility Theory [2011], 'How') | |||
| A reaction: That is (I think) that you can defeat the background, the likelihood, or the truth. He cites Pollock 1986, and implies that these are standard distinctions about defeaters. |
| 'Significance' | p.163 | 19718 | Indefeasibility does not imply infallibility |
| Full Idea: Infallibility does not follow from indefeasibility. | |||
| From: Thomas Grundmann (Defeasibility Theory [2011], 'Significance') | |||
| A reaction: If very little evidence exists then this could clearly be the case. It is especially true of historical and archaeological evidence. |
| 'Significance' | p.164 | 19719 | 'Moderate' foundationalism has basic justification which is defeasible |
| Full Idea: Theories that combine basic justification with the defeasibility of this justification are referred to as 'moderate' foundationalism. | |||
| From: Thomas Grundmann (Defeasibility Theory [2011], 'Significance') | |||
| A reaction: I could be more sympathetic to this sort of foundationalism. But it begins to sound more like Neurath's boat (see Quine) than like Descartes' metaphor of building foundations. |
| 'What' | p.157 | 19714 | Knowledge requires that there are no facts which would defeat its justification |
| Full Idea: The 'defeasibility theory' of knowledge claims that knowledge is only present if there are no facts that - if they were known - would be genuine defeaters of the relevant justification. | |||
| From: Thomas Grundmann (Defeasibility Theory [2011], 'What') | |||
| A reaction: Something not right here. A genuine defeater would ensure the proposition was false, so it would simply fail the truth test. So we need a 'defeater' for a truth, which must therefore by definition be misleading. Many qualifications have to be invoked. |
| 'What' | p.157 | 19713 | Defeasibility theory needs to exclude defeaters which are true but misleading |
| Full Idea: Advocates of the defeasibility theory have tried to exclude true pieces of information that are misleading defeaters. | |||
| From: Thomas Grundmann (Defeasibility Theory [2011], 'What') | |||
| A reaction: He gives as an example the genuine news of a claim that the suspect has a twin. |