21 ideas
| 23657 | The existence of tensed verbs shows that not all truths are necessary truths [Reid] |
| Full Idea: If all truths were necessary truths, there would be no occasion for different tenses in the verbs by which they are expressed. | |
| From: Thomas Reid (Essays on Intellectual Powers 6: Judgement [1785], 5) | |
| A reaction: This really is like modern linguistic analysis. Of course the tensed verbs might only indicate times when the universal necessities have been noticed by speakers. …But then the noticing would be contingent! |
| 23655 | An ad hominem argument is good, if it is shown that the man's principles are inconsistent [Reid] |
| Full Idea: It is a good argument ad hominem, if it can be shewn that a first principle which a man rejects, stands upon the same footing with others which he admits, …for he must then be guilty of an inconsistency. | |
| From: Thomas Reid (Essays on Intellectual Powers 6: Judgement [1785], 4) | |
| A reaction: Good point. You can't divorce 'pure' reason from the reasoners, because the inconsistency of two propositions only matters when they are both asserted together. …But attacking the ideas isn't quite the same as attacking the person. |
| 18151 | Could we replace sets by the open sentences that define them? [Chihara, by Bostock] |
| Full Idea: Chihara proposes to replace all sets by reference to the open sentences that define them. | |
| From: report of Charles Chihara (Ontology and the Vicious Circle Principle [1973]) by David Bostock - Philosophy of Mathematics 9.B.4 | |
| A reaction: This depends on predicativism, because that stipulates the definitions will be available (cos if it ain't definable it ain't there). Chihara went on to define the open sentences in terms of the possibility of uttering them. Cf. propositional functions. |
| 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. |
| 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. |
| 23659 | If someone denies that he is thinking when he is conscious of it, we can only laugh [Reid] |
| Full Idea: If any man could be found so frantic as to deny that he thinks, while he is conscious of it, I may wonder, I may laugh, or I may pity him, but I cannot reason the matter with him. | |
| From: Thomas Reid (Essays on Intellectual Powers 6: Judgement [1785], 5) | |
| A reaction: An example of the influence of Descartes' Cogito running through all subsequent European philosophy. There remain the usual questions about personal identity which then arise, but Reid addresses those. |
| 23662 | The existence of ideas is no more obvious than the existence of external objects [Reid] |
| Full Idea: If external objects be perceived immediately, we have the same reason to believe their existence as philosophers have to believe the existence of ideas. | |
| From: Thomas Reid (Essays on Intellectual Powers 6: Judgement [1785], 5) | |
| A reaction: He doesn't pay much attention to mirages and delusions, but in difficult conditions of perception we are confident of our experiences but doubtful about the objects they represent. |
| 23661 | We are only aware of other beings through our senses; without that, we are alone in the universe [Reid] |
| Full Idea: We can have no communication, no correspondence or society with any created being, but by means of our senses. And, until we rely on their testimony, we must consider ourselves as being alone in the universe. | |
| From: Thomas Reid (Essays on Intellectual Powers 6: Judgement [1785], 5) | |
| A reaction: I'm not aware of any thinker before this so directly addressing solipsism. Even the champion of direct and common sense realism has to recognise the intermediary of our senses when accepting other minds. |
| 23654 | In obscure matters the few must lead the many, but the many usually lead in common sense [Reid] |
| Full Idea: In matters beyond the reach of common understanding, the many are led by the few, and willingly yield to their authority. But, in matters of common sense, the few must yield to the many, when local and temporary prejudices are removed. | |
| From: Thomas Reid (Essays on Intellectual Powers 6: Judgement [1785], 4) | |
| A reaction: Wishful thinking in the 21st century, when the many routinely deny the authority of the expert few, and the expert few occasionally prove that the collective common sense of the many is delusional. I still sort of agree with Reid. |
| 23660 | The theory of ideas, popular with philosophers, means past existence has to be proved [Reid] |
| Full Idea: The theory concerning ideas, so generally received by philosophers, destroys all the authority of memory. …This theory made it necessary for them to find out arguments to prove the existence of external objects …and of things past. | |
| From: Thomas Reid (Essays on Intellectual Powers 6: Judgement [1785], 5) | |
| A reaction: Reid was a very articulate direct realist. He seems less aware than the rest of us of the problem of delusions and false memories. Our strong sense that immediate memories are reliable is certainly inexplicable. |
| 23658 | Consciousness is an indefinable and unique operation [Reid] |
| Full Idea: Consciousness is an operation of the understanding of its own kind, and cannot be logically defined. | |
| From: Thomas Reid (Essays on Intellectual Powers 6: Judgement [1785], 5) | |
| A reaction: It is interesting that has tried to define consciousness, rather than just assuming it. I note that he calls consciousness an 'operation', rather than an entity. Good. |
| 23656 | The structure of languages reveals a uniformity in basic human opinions [Reid] |
| Full Idea: What is common in the structure of languages, indicates an uniformity of opinion in those things upon which that structure is grounded. | |
| From: Thomas Reid (Essays on Intellectual Powers 6: Judgement [1785], 4) | |
| A reaction: Reid was more interested than his contemporaries in the role of language in philosophy. The first idea sounds like Chomsky. I would add to this that the uniformity of common opinion reflects uniformities in the world they are talking about. |
| 23653 | If you can't distinguish the features of a complex object, your notion of it would be a muddle [Reid] |
| Full Idea: If you perceive an object, white, round, and a foot in diameter, if you had not been able to distinguish the colour from the figure, and both from the magnitude, your senses would only give you one complex and confused notion of all these mingled together | |
| From: Thomas Reid (Essays on Intellectual Powers 6: Judgement [1785], 1) | |
| A reaction: His point is that if you reject the 'abstraction' of these qualities, you still cannot deny that distinguishing them is an essential aspect of perceiving complex things. Does this mean that animals distinguish such things? |
| 23663 | There are axioms of taste - such as a general consensus about a beautiful face [Reid] |
| Full Idea: I think there are axioms, even in matters of taste. …I never heard of any man who thought it a beauty in a human face to want a nose, or an eye, or to have the mouth on one side. | |
| From: Thomas Reid (Essays on Intellectual Powers 6: Judgement [1785], 6) | |
| A reaction: It is hard to disagree, but the human face may be a special case, since it is so deeply embedded in the minds of even the youngest infants. More recent artists seem able to discover beauty in very unlikely places. |