14 ideas
| 5300 | Philosophers have interpreted the world, but the point is to change it [Marx] |
| Full Idea: The philosophers have only interpreted the world, in various ways; the point is to change it. | |
| From: Karl Marx (Theses on Feuerbach [1846], §XI) | |
| A reaction: The 'point' of what? Personally I am more with Aristotle - that the aim is to create a society in which we can all aspire to contemplate like gods. As an interim statement of aim, though, one must respect Marx. But was he a philosopher? |
| 5297 | Whether human thinking can be 'true' must be decided in practice, not theory [Marx] |
| Full Idea: The question whether objective truth can be attributed to human thinking is not a question of theory but is a practical question; man must prove the truth of his thinking in practice. | |
| From: Karl Marx (Theses on Feuerbach [1846], §II) | |
| A reaction: This would appear to be an assertion of the pragmatic view of truth well before Peirce. The obvious objections arise, such as whether falsehood (Plato's 'noble lie') might not have equal practical success, and whether truth might be disastrous. |
| 15375 | If terms change their designations in different states, they are functions from states to objects [Fitting] |
| Full Idea: The common feature of every designating term is that designation may change from state to state - thus it can be formalized by a function from states to objects. | |
| From: Melvin Fitting (Intensional Logic [2007], 3) | |
| A reaction: Specifying the objects sounds OK, but specifying states sounds rather tough. |
| 15376 | Intensional logic adds a second type of quantification, over intensional objects, or individual concepts [Fitting] |
| Full Idea: To first order modal logic (with quantification over objects) we can add a second kind of quantification, over intensions. An intensional object, or individual concept, will be modelled by a function from states to objects. | |
| From: Melvin Fitting (Intensional Logic [2007], 3.3) |
| 15378 | Awareness logic adds the restriction of an awareness function to epistemic logic [Fitting] |
| Full Idea: Awareness logic enriched Hintikka's epistemic models with an awareness function, mapping each state to the set of formulas we are aware of at that state. This reflects some bound on the resources we can bring to bear. | |
| From: Melvin Fitting (Intensional Logic [2007], 3.6.1) | |
| A reaction: [He cites Fagin and Halpern 1988 for this] |
| 15379 | Justication logics make explicit the reasons for mathematical truth in proofs [Fitting] |
| Full Idea: In justification logics, the logics of knowledge are extended by making reasons explicit. A logic of proof terms was created, with a semantics. In this, mathematical truths are known for explicit reasons, and these provide a measure of complexity. | |
| From: Melvin Fitting (Intensional Logic [2007], 3.6.1) |
| 11026 | Classical logic is deliberately extensional, in order to model mathematics [Fitting] |
| Full Idea: Mathematics is typically extensional throughout (we write 3+2=2+3 despite the two terms having different meanings). ..Classical first-order logic is extensional by design since it primarily evolved to model the reasoning of mathematics. | |
| From: Melvin Fitting (Intensional Logic [2007], §1) |
| 13827 | Logical consequence isn't a black box (Tarski's approach); we should explain how arguments work [Prawitz] |
| Full Idea: Defining logical consequence in the way Tarski does is a rather meagre result, treating an argument as a black box, observing input and output, while disregarding inner structure. We should define logical consequence on the basis of valid arguments. | |
| From: Dag Prawitz (On the General Idea of Proof Theory [1974], §2) |
| 11028 | λ-abstraction disambiguates the scope of modal operators [Fitting] |
| Full Idea: λ-abstraction can be used to abstract and disambiguate a predicate. De re is [λx◊P(x)](f) - f has the possible-P property - and de dicto is ◊[λxP(x)](f) - possibly f has the P-property. Also applies to □. | |
| From: Melvin Fitting (Intensional Logic [2007], §3.3) | |
| A reaction: Compare the Barcan formula. Originated with Church in the 1930s, and Carnap 1947, but revived by Stalnaker and Thomason 1968. Because it refers to the predicate, it has a role in intensional versions of logic, especially modal logic. |
| 13826 | Model theory looks at valid sentences and consequence, but not how we know these things [Prawitz] |
| Full Idea: In model theory, which has dominated the last decades, one concentrates on logically valid sentences, and what follows logically from what, but one disregards questions concerning how we know these things. | |
| From: Dag Prawitz (On the General Idea of Proof Theory [1974], §1) |
| 15377 | Definite descriptions pick out different objects in different possible worlds [Fitting] |
| Full Idea: Definite descriptions pick out different objects in different possible worlds quite naturally. | |
| From: Melvin Fitting (Intensional Logic [2007], 3.4) | |
| A reaction: A definite description can pick out the same object in another possible world, or a very similar one, or an object which has almost nothing in common with the others. |
| 22598 | The authentic self exists at the level of class, rather than the individual [Marx, by Dunt] |
| Full Idea: Instead of focusing on the individual, Marxism suggested that the authentic self was at the social level in the form of class. | |
| From: report of Karl Marx (Theses on Feuerbach [1846]) by Ian Dunt - How to be a Liberal 6 | |
| A reaction: [not sure of the best source in Marx] This idea is expressed here by a defender of liberal individualism. Dunt persuasively attacks any concept of the self as part of some group, rather than as being an individual. |
| 5298 | The human essence is not found in individuals but in social relations [Marx] |
| Full Idea: The human essence is no abstraction inherent in each single individual; in its reality it is the ensemble of the social relations. | |
| From: Karl Marx (Theses on Feuerbach [1846], §VI) | |
| A reaction: This is a key Marxist doctrine, and the central difference from Aristotle. Personally I am more with Aristotle, but the truth obviously lies somewhere in between. Man must be a 'social being', or there wouldn't be any social relations. |
| 5299 | Religious feeling is social in origin [Marx] |
| Full Idea: The "religious sentiment" (discussed by Feuerbach) is itself a social product. | |
| From: Karl Marx (Theses on Feuerbach [1846], §VII) | |
| A reaction: Recent brain research has identified a part of the brain which is only active during religious thought and experience. It is easy to produce cynical political accounts of religion, but in its time it was also quite a good scientific account of nature. |