Ideas from 'Possible Worlds and Necessary A Posteriori' by Frank Jackson [2010], by Theme Structure

[found in 'Modality' (ed/tr Hale,B/Hoffman,A) [OUP 2010,]].

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9. Objects / D. Essence of Objects / 9. Essence and Properties
How do we tell a table's being contingently plastic from its being essentially plastic?
                        Full Idea: On a friendly reading of Quine, there is nothing to make the difference between a table's being contingently plastic and its being essentially plastic.
                        From: Frank Jackson (Possible Worlds and Necessary A Posteriori [2010], 5)
                        A reaction: This is, of course, the dreaded modern usage of 'essential' to just mean 'necessary' and nothing more. In my view, there may be a big problem with knowing whether a problem is necessary, but knowing whether it is essential is much easier.
An x is essentially F if it is F in every possible world in which it appears
                        Full Idea: On the possible world's account, x's being essentially F is nothing more nor less than x's being F in every world in which it appears.
                        From: Frank Jackson (Possible Worlds and Necessary A Posteriori [2010], 6)
                        A reaction: There you go - 'true in every possible world' is the definition of metaphysical necessity, not the definition of essence. Either get back to Aristotle, or stop (forever!) talking about 'essence'!
9. Objects / D. Essence of Objects / 15. Against Essentialism
Quine may have conflated de re and de dicto essentialism, but there is a real epistemological problem
                        Full Idea: The unfriendly response to Quine's objection to essentialism is that it conflates the de re and the de dicto. The friendly response is that behind that conflation is a real epistemological problem for essentialism.
                        From: Frank Jackson (Possible Worlds and Necessary A Posteriori [2010], 1)
                        A reaction: He cites Richard Cartwright 1968 for the friendly response. The epistemological question is how we can know the essentialness of an essence.
10. Modality / D. Knowledge of Modality / 3. A Posteriori Necessary
How can you show the necessity of an a posteriori necessity, if it might turn out to be false?
                        Full Idea: If something is offered as a candidate necessary a posteriori truth, how could we show that it is necessary, in the face of the fact that it takes investigation to show that it is true, and so, in some sense, it might have turned out to be false?
                        From: Frank Jackson (Possible Worlds and Necessary A Posteriori [2010], 1)
                        A reaction: This is the topic of his paper, which he compares with how we can know that essences are essential.