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Single Idea 5623

[filed under theme 2. Reason / A. Nature of Reason / 1. On Reason ]

Full Idea

If I know that the earth is a sphere, and its surface the surface of a sphere, then from a small part of the latter I can know the diameter, and hence the complete boundary, and in accordance with a priori principles.

Gist of Idea

If I know the earth is a sphere, and I am on it, I can work out its area from a small part

Source

Immanuel Kant (Critique of Pure Reason [1781], B787/A757)

Book Ref

Kant,Immanuel: 'Critique of Pure Reason', ed/tr. Guyer,P /Wood,A W [CUO 1998], p.653

A Reaction

A nice example, though it may be optimistic in its assumption that you can know you are on a sphere rather than an egg-shape. I agree with Kant, but speculative metaphysics should always be accompanied by humility and health warnings.

The 34 ideas with the same theme [general role of reason in mind and living]:

1502 Parmenides was much more cautious about accepting ideas than his predecessors [Simplicius on Parmenides]
243 It is foolish to quarrel with the mind's own reasoning processes [Plato]
224 When questions are doubtful we should concentrate not on objects but on ideas of the intellect [Plato]
11283 There is pure deductive reasoning, and explanatory demonstration reasoning [Aristotle, by Politis]
23250 Desired responsible actions result either from rational or from irrational desire [Aristotle]
2676 Didactic argument starts from the principles of the subject, not from the opinions of the learner [Aristotle]
1848 We are coerced into assent to a truth by reason's violence [Aquinas]
22708 Good reasons must give way to better [Shakespeare]
13009 A reason is a known truth which leads to assent to some further truth [Leibniz]
16897 Reason is the faculty for grasping apriori necessary truths [Leibniz, by Burge]
6253 Reason is our power of finding out true propositions [Hutcheson]
5604 In reason things can only begin if they are voluntary [Kant]
5622 The boundaries of reason can only be determined a priori [Kant]
5623 If I know the earth is a sphere, and I am on it, I can work out its area from a small part [Kant]
21416 Philosophers should not offer multiple proofs - suggesting the weakness of each of them [Kant]
21974 The world seems rational to those who look at it rationally [Hegel]
7083 Highest reason is aesthetic, and truth and good are subordinate to beauty [Hegel]
17892 For clear questions posed by reason, reason can also find clear answers [Gödel]
23945 Reason is actually passions, guided by perspicacious reflection [Solomon]
3811 Entailment and validity are relations, but inference is a human activity [Searle]
3822 Theory involves accepting conclusions, and so is a special case of practical reason [Searle]
19304 The rules of reasoning are not the rules of logic [Harman]
19307 If there is a great cost to avoiding inconsistency, we learn to reason our way around it [Harman]
19309 Logic has little relevance to reasoning, except when logical conclusions are immediate [Harman]
19306 It is a principle of reasoning not to clutter your mind with trivialities [Harman]
6950 You can be rational with undetected or minor inconsistencies [Harman]
3099 Inference is never a conscious process [Harman]
23249 The early philosophers thought that reason has its own needs and desires [Frede,M]
9429 Many forms of reasoning, such as extrapolation and analogy, are useful but deductively invalid [Mumford]
4767 Traditionally, rational beliefs are those which are justified by reasons [Psillos]
20955 Art can make reason more all-inclusive, by articulating what seemed inexpressible [Bowie]
5750 Consistency is modal, saying propositions are consistent if they could be true together [Melia]
6585 Rationality is threatened by fear of inconsistency, illusions of absolutes or relativism, and doubt [Fogelin]
8952 We reach 'reflective equilibrium' when intuitions and theory completely align [Fisher]