Combining Texts

All the ideas for 'The Sign of Four', 'Elements of Mathematical Logic' and 'Resurrecting Biological Essentialism'

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6 ideas

4. Formal Logic / E. Nonclassical Logics / 3. Many-Valued Logic

8942	Lukasiewicz's L3 logic has three truth-values, T, F and I (for 'indeterminate') [Lukasiewicz, by Fisher]
	Full Idea: In response to Aristotle's sea-battle problem, Lukasiewicz proposed a three-valued logic that has come to be known as L3. In addition to the values true and false (T and F), there is a third truth-value, I, meaning 'indeterminate' or 'possible'.
	From: report of Jan Lukasiewicz (Elements of Mathematical Logic [1928], 7.I) by Jennifer Fisher - On the Philosophy of Logic
	A reaction: [He originated the idea in 1917] In what sense is the third value a 'truth' value? Is 'I don't care' a truth-value? Or 'none of the above'? His idea means that formalization doesn't collapse when things get obscure. You park a few propositions under I.

9. Objects / D. Essence of Objects / 10. Essence as Species

17368	Essentialism concerns the nature of a group, not its category [Devitt]
	Full Idea: Essentialism is concerned with the nature of a group, whatever the category it falls under.
	From: Michael Devitt (Resurrecting Biological Essentialism [2008], 6)
	A reaction: This seems to me such a simple and obvious point that I am amazed that anyone rejects it, yet lots of people seem to think that an essence is just some sort of category.

17370	Things that gradually change, like species, can still have essences [Devitt]
	Full Idea: An intrinsic essence does not have to be 'neat and tidy'. ...Essentialism can accept the gradual change of one thing into another.
	From: Michael Devitt (Resurrecting Biological Essentialism [2008], 11)
	A reaction: My thesis is that essentialism is a response to the needs of explanation, so as long as there is some core explanation to be found, even in something transitory, then the concept of an essence can apply to it.

14. Science / C. Induction / 1. Induction

22200	If you eliminate the impossible, the truth will remain, even if it is weird [Conan Doyle]
	Full Idea: When you have eliminated the impossible, whatever remains, however improbable, must be the truth.
	From: Arthur Conan Doyle (The Sign of Four [1890], Ch. 6)
	A reaction: A beautiful statement, by Sherlock Holmes, of Eliminative Induction. It is obviously not true, of course. Many options may still face you after you have eliminated what is actually impossible.

27. Natural Reality / G. Biology / 5. Species

17369	We name species as small to share properties, but large enough to yield generalisations [Devitt]
	Full Idea: Our explanatory purposes in introducing a name for a species demand that we draw the lines around a group that is small enough to share a whole lot of important properties and large enough to yield broad generalizations.
	From: Michael Devitt (Resurrecting Biological Essentialism [2008], 10 'Arb')
	A reaction: Grist to my mill. In this reaction slot (16th Oct 2013) I launch my new metaphysical school - welcome to EXPLANATIONISM! Folk metaphysics, and the best philosophical metaphysics, is entirely driven by the needs of explanation.

17367	Species are phenetic, biological, niche, or phylogenetic-cladistic [Devitt, by PG]
	Full Idea: The four main concepts of a species are 'phenetic' (similarity of traits), 'biological species' (interbreeding and isolated), 'ecological niche' (occupying an adaptive zone), or 'phylogenetic-cladistic' (start and finish at splits in lineage)
	From: report of Michael Devitt (Resurrecting Biological Essentialism [2008], 4) by PG - Db (ideas)
	A reaction: [my summary of Devitt's list] Devitt attacks the whole lot, in favour of essentialism - the species being fixed by its underlying explanatory mechanisms.