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14. Science / A. Basis of Science / 2. Demonstration

[proving physical facts by observation and reason]

27 ideas
Demonstration starts from a definition of essence, so we can derive (or conjecture about) the properties [Aristotle]
     Full Idea: In demonstration a definition of the essence is required as starting point, so that definitions which do not enable us to discover the derived properties, or which fail to facilitate even a conjecture about them, must obviously be dialectical and futile.
     From: Aristotle (De Anima [c.329 BCE], 402b25)
     A reaction: Interesting to see 'dialectical' used as a term of abuse! Illuminating. For scientific essentialism, then, demonstration is filling out the whole story once the essence has been inferred. It is circular, because essence is inferred from accidents.
Demonstrations move from starting-points to deduced conclusions [Aristotle]
     Full Idea: Demonstrations are both from a starting-point and have a sort of end, namely the deduction or the conclusion.
     From: Aristotle (De Anima [c.329 BCE], 407a25)
     A reaction: A starting point has to be a first principle [arché]. It has been observed that Aristotle explains demonstration very carefully, but rarely does it in his writings.
There cannot be a science of accidentals, but only of general truths [Aristotle]
     Full Idea: It is not even possible for there to be a science of the accidental, ...for any field of science is either 'always' or 'for the most part'.
     From: Aristotle (Metaphysics [c.324 BCE], 1065b30-)
     A reaction: His example of an accident (and thus outside of any science) is a cold spell in high summer. This leaves us trying to explain the unusually tame tiger. Copi comments (p.717), rightly I think, that modern science disagrees with Aristotle on this.
Demonstrations about particulars must be about everything of that type [Aristotle]
     Full Idea: There cannot be demonstrations that this particular triangle is equal to the sum of two right angles, except that every triangle is equal to the sum of two right angles, nor that this particular man is an animal, except that every man is an animal.
     From: Aristotle (Metaphysics [c.324 BCE], 1086b36)
     A reaction: Not quite the covering-law model, but well on the way. Why can't we demonstrate that this particular is different from the others? This tiger is docile; this butterfly stings. We just like generalisations because you know more with less effort.
Demonstration is more than entailment, as the explanatory order must match the causal order [Aristotle, by Koslicki]
     Full Idea: Aristotle's demonstration encompasses more than deductive entailment, in that the explanatory order of priority represented in a successful demonstration must mirror precisely the causal order of priority in the phenomena in question.
     From: report of Aristotle (Posterior Analytics [c.327 BCE]) by Kathrin Koslicki - Form, Matter and Substance 4.5
     A reaction: Interesting. I presume this is correct, but is not an aspect I had registered. In Metaphysics his essentialist explanations are causal, so it all hangs together.
Aristotle gets asymmetric consequence from demonstration, which reflects real causal priority [Aristotle, by Koslicki]
     Full Idea: In Aristotle's system, the relevant notion of asymmetric consequence that is operative in his model of scientific explanation is that of demonstration. ...It is a theoretical/linguistic reflection of an asymmetric real-world relation of causal priority.
     From: report of Aristotle (Posterior Analytics [c.327 BCE]) by Kathrin Koslicki - Varieties of Ontological Dependence 7.3 n7
     A reaction: The asymmetry is required for explanation, and for grounding.
Aristotle doesn't actually apply his theory of demonstration to his practical science [Leroi on Aristotle]
     Full Idea: There is a conflict between the syllogistic theory of demonstration of the Posterior Analytics, with its austere programme of certainties, and how Aristotle actually does science.
     From: comment on Aristotle (Posterior Analytics [c.327 BCE]) by Armand Marie LeRoi - The Lagoon: how Aristotle invented science 104
     A reaction: Leroi observes that there are no demonstrations anywhere in the biological writings. Biology probably lends itself least to such an approach.
We can know by demonstration, which is a scientific deduction leading to understanding [Aristotle]
     Full Idea: We know things through demonstration, by which I mean a scientific deduction, and by 'scientific' I mean a deduction by possessing which we understand something.
     From: Aristotle (Posterior Analytics [c.327 BCE], 71b17)
     A reaction: This is a distinctively Aristotelian account of what science aims at, and which seems to have dropped out of modern accounts of science, which are still under the influence of logical positivism. Time to revive it.
Premises must be true, primitive and immediate, and prior to and explanatory of conclusions [Aristotle]
     Full Idea: Demonstrative understanding must proceed from items which are true and primitive and immediate and more familiar and prior to and explanatory of the conclusions.
     From: Aristotle (Posterior Analytics [c.327 BCE], 71b22)
A demonstration is a deduction which proceeds from necessities [Aristotle]
     Full Idea: A demonstration is a deduction which proceeds from necessities.
     From: Aristotle (Posterior Analytics [c.327 BCE], 73a24)
     A reaction: Elsewhere he tells us that demonstration that brings understanding (Idea 12365), so this is an interesting gloss. He says that the middle term of the syllogism gives the understanding, but necessities reside in the whole propositions of the premisses.
Demonstrative understanding rests on necessary features of the thing in itself [Aristotle]
     Full Idea: If demonstrative understanding proceeds from necessary principles, and whatever holds of an object in itself is necessary, then it is clear that demonstrative deductions will proceed from certain items of this sort.
     From: Aristotle (Posterior Analytics [c.327 BCE], 74b05-)
     A reaction: This is the characterization of the essence of something in terms of what counts as a good explanation of that thing. Although explanation is a bit subjective, I like this approach, because you will dig down to the source of the powers of the thing.
Demonstrations must be necessary, and that depends on the middle term [Aristotle]
     Full Idea: If you understand something demonstratively, it must hold from necessity, so it is plain that your demonstration must proceed through a middle term which is necessary.
     From: Aristotle (Posterior Analytics [c.327 BCE], 75a13)
     A reaction: How can a middle 'term' be necessary, if it is not a proposition? Presumably Socrates is necessarily a man, and men are necessarily mortal, so it is the predication which is necessary.
All demonstration is concerned with existence, axioms and properties [Aristotle]
     Full Idea: All demonstrative science [apodeiktike episteme] is concerned with three things: what it posits to exist (the kind), the axioms (primitives basic to demonstration), and the attributes.
     From: Aristotle (Posterior Analytics [c.327 BCE], 76b12)
Demonstrations are syllogisms which give explanations [Aristotle]
     Full Idea: Demonstrations are probative deductions [sullogismos] which give the explanation [aitias] and the reason why.
     From: Aristotle (Posterior Analytics [c.327 BCE], 85b24)
     A reaction: This notion seems to have slipped out of modern philosophy of science, because (while scientists have just pressed on) philosophers of science have raised so many sceptical questions that they have, I would say, lost the plot.
Universal demonstrations are about thought; particular demonstrations lead to perceptions [Aristotle]
     Full Idea: Universal demonstrations are objects of thought, particular demonstrations terminate in perception.
     From: Aristotle (Posterior Analytics [c.327 BCE], 86a30)
Demonstration is better with fewer presuppositions, and it is quicker if these are familiar [Aristotle]
     Full Idea: A demonstration is superior if it depends on fewer suppositions or propositions - for if these are familiar, knowledge will come more quickly, and this is preferable.
     From: Aristotle (Posterior Analytics [c.327 BCE], 86a35)
The principles of demonstrations are definitions [Aristotle]
     Full Idea: The principles of demonstrations are definitions.
     From: Aristotle (Posterior Analytics [c.327 BCE], 90b25)
     A reaction: This I take to be a key idea linking Aristotle's desire to understand the world, by using demonstrations to reach good explanations. Definitions turn out to rest on essences, so our understanding of the world rests on essences.
There must be definitions before demonstration is possible [Aristotle]
     Full Idea: There is no demonstration of anything of which there is no definition. Definitions are of what something is, i.e. of its essence, but all demonstrations clearly suppose and assume what a thing is.
     From: Aristotle (Posterior Analytics [c.327 BCE], 90b30)
     A reaction: Note that while essentialism rests on definitions, the job is not yet complete once the definitions are done. With good definitions, it should be easy to show how the pieces of the jigsaw fit together.
Aim to get definitions of the primitive components, thus establishing the kind, and work towards the attributes [Aristotle]
     Full Idea: Divide a whole into its primitives, then try to get definitions of these. Thus you establish the kind, and then study the attributes through the primitive common items.
     From: Aristotle (Posterior Analytics [c.327 BCE], 96b16)
Demonstration derives what is less clear from what is clear [Stoic school, by Diog. Laertius]
     Full Idea: Demonstration is an argument which by means of things more clearly grasped concludes to something that is less clearly grasped.
     From: report of Stoic school (fragments/reports [c.200 BCE]) by Diogenes Laertius - Lives of Eminent Philosophers 07.45
     A reaction: In Aristotle demonstration seems to concern physical sciences, but this stoic account makes it sound like pure logic proof. This is why all logic tends to start from atomic sentences, because they are clearest.
Induction is not demonstration, because not all of the instances can be observed [Buridan]
     Full Idea: Inductions are not demonstrations, because they do not conclude on account of their form, since it is not possible to make an induction from all cases.
     From: Jean Buridan (Questions on Aristotle's Physics [1346], I.15 f. 18vb), quoted by Robert Pasnau - Metaphysical Themes 1274-1671 02.3
     A reaction: Thus showing that demonstration really is meant to be as conclusive as a mathematical proof, and that Aristotle seems to think such a thing is possible in physical science.
If each inference slightly reduced our certainty, science would soon be in trouble [Peirce]
     Full Idea: Were every probable inference less certain than its premises, science, which piles inference upon inference, often quite deeply, would soon be in a bad way.
     From: Charles Sanders Peirce (Reasoning and the Logic of Things [1898], IV)
     A reaction: This seems to endorse Aristotle's picture of demonstration about scientific and practical things as being a form of precise logic, rather than progressive probabilities. Our generalisations may be more certain than the particulars they rely on.
Inductive inference is not proof, but weighing evidence and probability [Lipton]
     Full Idea: Inductive inference is a matter of weighing evidence and judging probability, not of proof.
     From: Peter Lipton (Inference to the Best Explanation (2nd) [2004], 01 'Underd')
     A reaction: This sounds like a plausible fallibilist response to the optimistic view of Aristotle.
We infer from evidence by working out what would explain that evidence [Lipton]
     Full Idea: Explanatory considerations are an important guide to inference, …we work out what to infer from our evidence by thinking about what would explain that evidence.
     From: Peter Lipton (Inference to the Best Explanation (2nd) [2004], Pref 2nd ed)
     A reaction: I take this to be inferences about the physical world, rather than of pure logic. The thesis sounds a bit thin, since there is no logical sense of 'infer' here, so all it could mean is 'what caused that?'.
Demonstration provides depth of understanding and explanation (rather than foundations) [Kretzmann/Stump]
     Full Idea: According to Aquinas, what demonstration provides is not so much knowledge as conceived by foundationalists as depth of understanding and explanatory insight.
     From: Kretzmann/Stump (Aquinas, Thomas [2005]), quoted by Kretzmann/Stump - Aquinas, Thomas 11
     A reaction: It was noticeable that Aristotle didn't make clear what demonstration aims to achieve, and he didn't employ it elsewhere in his writings. We aim for understanding, not for well grounded propositions. Understanding needs implications and mechanisms.
In demonstration, the explanatory order must mirror the causal order of the phenomena [Koslicki]
     Full Idea: Demonstration encompasses more than deductive entailment, in that the explanatory order of priority represented in a successful demonstration must mirror precisely the causal order of priority present in the phenomena in question.
     From: Kathrin Koslicki (Essence, Necessity and Explanation [2012], 13.1)
     A reaction: She is referring to Aristotle's 'Posterior Analytics'. Put so clearly this sounds like an incredibly useful concept in discussing how we present good modern scientific explanations. Reinstating Aristotle is a major priority for philosophy!
In a demonstration the middle term explains, by being part of the definition [Koslicki]
     Full Idea: In a proper demonstrative argument, the middle term must be explanatory of the conclusion, in a very specific sense: the middle term must state what properly belongs to the definition of the kind of phenomenon in question.
     From: Kathrin Koslicki (Essence, Necessity and Explanation [2012], 13.3.1)
     A reaction: So 'All men are mortal, S is a man, so S is mortal'. The middle term is 'man', which gives a generic explanation for why S is mortal. Explanation as categorisation? I don't think this is the whole story of Aristotelian explanation.