Combining Texts

All the ideas for 'On Motion', 'Reply to Fifth Objections' and 'Lectures on Ethics'

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7 ideas

9. Objects / B. Unity of Objects / 2. Substance / a. Substance
Knowing the attributes is enough to reveal a substance [Descartes]
     Full Idea: I have never thought that anything more is required to reveal a substance than its various attributes.
     From: René Descartes (Reply to Fifth Objections [1641], 360)
12. Knowledge Sources / A. A Priori Knowledge / 3. Innate Knowledge / a. Innate knowledge
Our thinking about external things doesn't disprove the existence of innate ideas [Descartes]
     Full Idea: You can't prove that Praxiteles never made any statues on the grounds that he did not get from within himself the marble from which he sculpted them.
     From: René Descartes (Reply to Fifth Objections [1641], 362)
18. Thought / D. Concepts / 2. Origin of Concepts / c. Nativist concepts
A blind man may still contain the idea of colour [Descartes]
     Full Idea: How do you know that there is no idea of colour in a man born blind?
     From: René Descartes (Reply to Fifth Objections [1641], 363)
25. Social Practice / F. Life Issues / 4. Suicide
The maxim for suicide is committed to the value of life, and is thus contradictory [Kant]
     Full Idea: If my maxim is to shorten my life if its continuance threatens more evil than pleasure ...it is seen that a system of nature by whose law the feeling intended to further life should actually destroy life would contradict itself, and could not subsist.
     From: Immanuel Kant (Lectures on Ethics [1780], 422:53)
     A reaction: [compressed] I take it this means that a potential suicide is assessing what is best for life, and is therefore implicitly committed to life. Not persuasive! Should we not terminate the life of a mass murderer in mid-crime?
27. Natural Reality / B. Modern Physics / 1. Relativity / a. Special relativity
Motion is not absolute, but consists in relation [Leibniz]
     Full Idea: In reality motion is not something absolute, but consists in relation.
     From: Gottfried Leibniz (On Motion [1677], A6.4.1968), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 3
     A reaction: It is often thought that motion being relative was invented by Einstein, but Leibniz wholeheartedly embraced 'Galilean relativity', and refused to even consider any absolute concept of motion. Acceleration is a bit trickier than velocity.
28. God / B. Proving God / 2. Proofs of Reason / a. Ontological Proof
Necessary existence is a property which is uniquely part of God's essence [Descartes]
     Full Idea: In the case of God necessary existence is in fact a property in the strictest sense of the term, since it applies to him alone and forms a part of his essence as it does of no other thing
     From: René Descartes (Reply to Fifth Objections [1641], 383)
Possible existence is a perfection in the idea of a triangle [Descartes]
     Full Idea: Possible existence is a perfection in the idea of a triangle, just as necessary existence is a perfection in the idea of God.
     From: René Descartes (Reply to Fifth Objections [1641], 383)