21 ideas
| 23269 | Philosophy must start from clearly observed facts [Galen] |
| Full Idea: True philosophers concern themselves first and foremost to take clearly observed facts as their point of departure. | |
| From: Galen (The soul's dependence on the body [c.170], Kiv.11.817) | |
| A reaction: I love this one, especially the desire that the facts be 'clearly observed'. That, thank goodness, eliminates quantum mechanics. If you don't love history and the physical sciences, you are not a philosopher. Oh, and reliable gossip. |
| 23248 | Early empiricists said reason was just a useless concept introduced by philosophers [Galen, by Frede,M] |
| Full Idea: The so-called Empiricists in Hellenistic times [as cited by Galen] denied the existence of reason, treating it as a useless theoretical postulate introduced by some philosophers | |
| From: report of Galen (An Outline of Empiricism [c.170], 87.4-9.28ff) by Michael Frede - Intro to 'Rationality in Greek Thought' p.3 | |
| A reaction: I think 'be sensible' is understood by everyone, but 'use your reason' is far from obvious. The main role of reason seems to be as an identifier for human exceptionalism. Animals obviously make good judgements. Frede thinks the empiricists were right. |
| 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) |
| 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. |
| 18086 | Weierstrass eliminated talk of infinitesimals [Weierstrass, by Kitcher] |
| Full Idea: Weierstrass effectively eliminated the infinitesimalist language of his predecessors. | |
| From: report of Karl Weierstrass (works [1855]) by Philip Kitcher - The Nature of Mathematical Knowledge 10.6 |
| 18092 | Weierstrass made limits central, but the existence of limits still needed to be proved [Weierstrass, by Bostock] |
| Full Idea: After Weierstrass had stressed the importance of limits, one now needed to be able to prove the existence of such limits. | |
| From: report of Karl Weierstrass (works [1855]) by David Bostock - Philosophy of Mathematics 4.4 | |
| A reaction: The solution to this is found in work on series (going back to Cauchy), and on Dedekind's cuts. |
| 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. |
| 23266 | The spirit in the soul wants freedom, power and honour [Galen] |
| Full Idea: The spirited part of the soul is desiderative of freedom, victory, power, authority, reputation, and honour. | |
| From: Galen (The soul's dependence on the body [c.170], Kiv.2.772) | |
| A reaction: This is the concept of 'thumos' [spirit], taken straight from Plato's tripartite account of the soul, in 'Republic'. Note that it includes a desire for freedom (in an age of slavery). |
| 6003 | Galen showed by experiment that the brain controls the body [Galen, by Hankinson] |
| Full Idea: Galen established by experiments in neural anatomy that the brain really is, contra the Stoics and Aristotelians, the body's control centre. | |
| From: report of Galen (On Hippocrates and Plato [c.170]) by R.J. Hankinson - Galen (damaged) | |
| A reaction: And about time too. This is one of the most significant events in the development of human understanding. No one has been able to go back to the old view, even Descartes, no matter how much they may long to do so. |
| 23219 | Stopping the heart doesn't terminate activity; pressing the brain does that [Galen, by Cobb] |
| Full Idea: Even when an animals heart was stopped [by hand] it continued its muted whimpers, …but when the brain was pressed the animal stopped making a noise and became unconscious. | |
| From: report of Galen (The soul's dependence on the body [c.170]) by Matthew Cobb - The Idea of the Brain 1 | |
| A reaction: It's not that the ancients didn't do science. It's that ancient people paid no attention to what their scientists discovered. |
| 21799 | We just use the word 'faculty' when we don't know the psychological cause [Galen] |
| Full Idea: So long as we are ignorant of the true essence of the cause which is operating, we call it a 'faculty'. | |
| From: Galen (On the Natural Faculties [c.170], I.iv), quoted by Dominik Perler - Intro to The Faculties: a History 2 | |
| A reaction: This is probably the view of most modern neuroscientists. I want to defend the idea that we need the concept of a faculty in philosophy, even if the psychologists and neuroscientists say it is too vague for their purposes. |
| 23264 | Philosophers think faculties are in substances, and invent a faculty for every activity [Galen] |
| Full Idea: Philosophers conceive of faculties as things which inhabit 'substances' much as we inhabit houses, not realising that causes of events are conceived in relational terms. We therefore attribute as many faculties to a substance as activities. | |
| From: Galen (The soul's dependence on the body [c.170], Kiv.2.769) | |
| A reaction: This seems to demolish speculative faculties, but they were revived during the Enlightenment. I am happy to talk of 'philosophical faculties' where they are presumed to originate a type of thought, without commitment to any neuroscience. |
| 23220 | The brain contains memory and reason, and is the source of sensation and decision [Galen] |
| Full Idea: The brain is the principal organ of the psychical members. For within the brain is seated memory, reason and intellect, and from the brain is distributed the power, sensation and voluntary motion. | |
| From: Galen (The soul's dependence on the body [c.170]), quoted by Matthew Cobb - The Idea of the Brain 1 | |
| A reaction: [not sure of ref] Interesting that he assigns the whole of mind to the brain, and not just some aspect of it. He had done experiments. Understanding the role of the brain was amazingly slow. Impeded by religion, I guess. |
| 23265 | The rational part of the soul is the desire for truth, understanding and recollection [Galen] |
| Full Idea: That part of the soul which we call rational is desiderative: …it desires truth, knowledge, learning, understanding, and recollection - in short, all the good things. | |
| From: Galen (The soul's dependence on the body [c.170], Kiv.2.772) | |
| A reaction: Truth is no surprise, but recollection is. Note the separation of knowledge from understanding. This is a very good characterisation of rationality. For the Greeks it has a moral dimension, of wanting what is good. |
| 7453 | Galen's medicine followed the mean; each illness was balanced by opposite treatment [Galen, by Hacking] |
| Full Idea: Galen ran medicine on the principle of the mean; afflictions must be treated by contraries; hot diseases deserve cold medicine and moist illnesses want drying agents. (Paracelsus rebelled, treating through similarity). | |
| From: report of Galen (On Medical Experience [c.169]) by Ian Hacking - The Emergence of Probability Ch.5 | |
| A reaction: This must be inherited from Aristotle, with the aim of virtue for the body, as Aristotle wanted virtue for the psuché. In some areas Galen is probably right, that natural balance is the aim, as in bodily temperature control. |
| 6030 | Each part of the soul has its virtue - pleasure for appetite, success for competition, and rectitude for reason [Galen] |
| Full Idea: We have by nature these three appropriate relationships, corresponding to each form of the soul's parts - to pleasure because of the appetitive part, to success because of the competitive part, and to rectitude because of the rational part. | |
| From: Galen (On Hippocrates and Plato [c.170], 5.5.8) | |
| A reaction: This is a nice combination of Plato's tripartite theory of soul (in 'Republic') and Aristotle's derivation of virtues from functions. Presumably, though, reason should master the other two, and there is nothing in Galen's idea to explain this. |
| 23268 | We execute irredeemable people, to protect ourselves, as a deterrent, and ending a bad life [Galen] |
| Full Idea: We kill the irredeemably wicked, for three reasons: that they may no longer harm us; as a deterrent to others like them; and because it is actually better from their own point of view to die, when their souls are so damaged they cannot be improved. | |
| From: Galen (The soul's dependence on the body [c.170], Kiv.11.816) | |
| A reaction: The third one sounds like a dubious rationalisation, given that the prisoner probably disagrees. Nowadays we are not so quick to judge someone as irredeemable. The first one works when they run wild, but not after their capture. |