16 ideas
18739 | Three stages of philosophical logic: syntactic (1905-55), possible worlds (1963-85), widening (1990-) [Horsten/Pettigrew] |
Full Idea: Three periods can be distinguished in philosophical logic: the syntactic stage, from Russell's definite descriptions to the 1950s, the dominance of possible world semantics from the 50s to 80s, and a current widening of the subject. | |
From: Horsten,L/Pettigrew,R (Mathematical Methods in Philosophy [2014], 1) | |
A reaction: [compressed] I've read elsewhere that the arrival of Tarski's account of truth in 1933, taking things beyond the syntactic, was also a landmark. |
18741 | Logical formalization makes concepts precise, and also shows their interrelation [Horsten/Pettigrew] |
Full Idea: Logical formalization forces the investigator to make the central philosophical concepts precise. It can also show how some philosophical concepts and objects can be defined in terms of others. | |
From: Horsten,L/Pettigrew,R (Mathematical Methods in Philosophy [2014], 2) | |
A reaction: This is the main rationale of the highly formal and mathematical approach to such things. The downside is when you impose 'precision' on language that was never intended to be precise. |
18744 | Models are sets with functions and relations, and truth built up from the components [Horsten/Pettigrew] |
Full Idea: A (logical) model is a set with functions and relations defined on it that specify the denotation of the non-logical vocabulary. A series of recursive clauses explicate how truth values of complex sentences are compositionally determined from the parts. | |
From: Horsten,L/Pettigrew,R (Mathematical Methods in Philosophy [2014], 3) | |
A reaction: See the ideas on 'Functions in logic' and 'Relations in logic' (in the alphabetical list) to expand this important idea. |
18740 | If 'exist' doesn't express a property, we can hardly ask for its essence [Horsten/Pettigrew] |
Full Idea: If there is indeed no property of existence that is expressed by the word 'exist', then it makes no sense to ask for its essence. | |
From: Horsten,L/Pettigrew,R (Mathematical Methods in Philosophy [2014], 2) | |
A reaction: As far as I can tell, this was exactly Aristotle's conclusion, so he skirted round the question of 'being qua being', and focused on the nature of objects instead. Grand continental talk of 'Being' doesn't sound very interesting. |
19400 | Possibles demand existence, so as many of them as possible must actually exist [Leibniz] |
Full Idea: From the conflict of all the possibles demanding existence, this at once follows, that there exists that series of things by which as many of them as possible exist. | |
From: Gottfried Leibniz (Exigency to Exist in Essences [1690], p.91) | |
A reaction: I'm in tune with a lot of Leibniz, but my head swims with this one. He seems to be a Lewisian about possible worlds - that they are concrete existing entities (with appetites!). Could Lewis include Leibniz's idea in his system? |
19401 | God's sufficient reason for choosing reality is in the fitness or perfection of possibilities [Leibniz] |
Full Idea: The sufficient reason for God's choice can be found only in the fitness (convenance) or in the degree of perfection that the several worlds possess. | |
From: Gottfried Leibniz (Exigency to Exist in Essences [1690], p.92) | |
A reaction: The 'fitness' of a world and its 'perfection' seem very different things. A piece of a jigsaw can have wonderful fitness, without perfection. Occasionally you get that sinking feeling with metaphysicians that they just make it up. |
19402 | The actual universe is the richest composite of what is possible [Leibniz] |
Full Idea: The actual universe is the collection of the possibles which forms the richest composite. | |
From: Gottfried Leibniz (Exigency to Exist in Essences [1690], p.92) | |
A reaction: 'Richest' for Leibniz means a maximum combination of existence, order and variety. It's rather like picking the best starting team from a squad of footballers. |
18745 | A Tarskian model can be seen as a possible state of affairs [Horsten/Pettigrew] |
Full Idea: A Tarskian model can in a sense be seen as a model of a possible state of affairs. | |
From: Horsten,L/Pettigrew,R (Mathematical Methods in Philosophy [2014], 3) | |
A reaction: I include this remark to show how possible worlds semantics built on the arrival of model theory. |
18747 | The 'spheres model' was added to possible worlds, to cope with counterfactuals [Horsten/Pettigrew] |
Full Idea: The notion of a possible worlds model was extended (resulting in the concept of a 'spheres model') in order to obtain a satisfactory logical treatment of counterfactual conditional sentences. | |
From: Horsten,L/Pettigrew,R (Mathematical Methods in Philosophy [2014], 4) | |
A reaction: Thus we add 'centred' worlds, and an 'actual' world, to the loose original model. It is important to remember when we discuss 'close' worlds that we are then committed to these presuppositions. |
18748 | Epistemic logic introduced impossible worlds [Horsten/Pettigrew] |
Full Idea: The idea of 'impossible worlds' was introduced into epistemic logic. | |
From: Horsten,L/Pettigrew,R (Mathematical Methods in Philosophy [2014], 4) | |
A reaction: Nathan Salmon seems interested in their role in metaphysics (presumably in relation to Meinongian impossible objects, like circular squares, which must necessarily be circular). |
18746 | Possible worlds models contain sets of possible worlds; this is a large metaphysical commitment [Horsten/Pettigrew] |
Full Idea: Each possible worlds model contains a set of possible worlds. For this reason, possible worlds semantics is often charged with smuggling in heavy metaphysical commitments. | |
From: Horsten,L/Pettigrew,R (Mathematical Methods in Philosophy [2014], 3) | |
A reaction: To a beginner it looks very odd that you should try to explain possibility by constructing a model of it in terms of 'possible' worlds. |
18750 | Using possible worlds for knowledge and morality may be a step too far [Horsten/Pettigrew] |
Full Idea: When the possible worlds semantics were further extended to model notions of knowledge and of moral obligation, the application was beginning to look distinctly forced and artificial. | |
From: Horsten,L/Pettigrew,R (Mathematical Methods in Philosophy [2014], 5) | |
A reaction: They accept lots of successes in modelling necessity and time. |
8808 | Involuntary beliefs can still be evaluated [Feldman/Conee] |
Full Idea: Examples confirm that beliefs may be both involuntary and subject to epistemic evaluation. | |
From: R Feldman / E Conee (Evidentialism [1985], II) | |
A reaction: This is an extremely important point, which summarises the situation with beliefs that arise from (apparent) immediate perception. A belief cannot possibly be knowledge if it has been triggered, but no effort was made to evaluate it. |
8807 | Evidentialism is the view that justification is determined by the quality of the evidence [Feldman/Conee] |
Full Idea: What we call 'evidentialism' is the view that the epistemic justification of a belief is determined by the quality of the believer's evidence for the belief. | |
From: R Feldman / E Conee (Evidentialism [1985], I) | |
A reaction: The immediate question is whether the believer knows the quality of their evidence. A detective might not recognise the crucial clue (like the dog not barking). The definition of 'quality' had better not turn out to be circular. Forgotten evidence? |
8809 | Beliefs should fit evidence, and if you ought to believe it, then you are justified [Feldman/Conee] |
Full Idea: One epistemically ought to have the doxastic attitudes that fit one's evidence. Being epistemically obligatory is equivalent to being epistemically justified. | |
From: R Feldman / E Conee (Evidentialism [1985], III) | |
A reaction: It is normal for someone to refuse to accept something, when another person believes the evidence is overwhelming. Evaluation of evidence must include an assessment of what other evidence might turn up. |
8810 | If someone rejects good criticism through arrogance, that is irrelevant to whether they have knowledge [Feldman/Conee] |
Full Idea: If an arrogant young physicist refuses to recognise valid criticisms from a senior colleague, his or her character has nothing to do with the epistemic status of their belief in the theory. | |
From: R Feldman / E Conee (Evidentialism [1985], III) | |
A reaction: This rejects the idea that epistemic justification is essentially a matter of virtues and vices of character. That view is a version of reliabilism, and hence of externalism. I agree with the criticism, but epistemic virtues are still significant. |