Dispositions and Twin Earth Sungho Choi Kyung Hee University

1. Dispositions and Twin Earth Sungho Choi Kyung Hee University

2. Alexander Bird “What we may conclude in the case of water is that we seek an analysis of the concept ‘water’ in vain, and that instead the extension of the concept is fixed by reference to certain archetypical examples of water (whence there is an unavoidable indexical element in the explanation of the concept). These are the conclusions I wish to draw regarding both concepts like ‘fragility’ and those like ‘being disposed to shatter when struck’.” Peter Lipton “Here as elsewhere in the philosophy of language, a situation where there is a combination of semantic determinacy and a lack of articulate knowledge about the extension or referent provides a strong argument for some form of semantic externalism. The idea, in roughest outline, would be that dispositional terms are natural kind terms that get their content by a combination of exemplary cases, theoretical knowledge and the actual kind structure of the world, not simply in virtue of what is in users’ heads.”

3. Dispositional terms and natural kind terms A semantic account of a dispositional term to be modelled after Putnam and Kripke’s semantic account of natural kind terms A dispositional term involves an implicit reference to the prevalent feature of a circumstance where x is typically expected to undergo the corresponding stimulus

4. Earth Planet Z

6. Gw

7. Gwe

8. WIZARD EARTH EARTH Kim Kim* Gwe Ge

9. Kim and Kim* They would be in precisely the same psychological states when they utter ‘Ge is fragile’ and ‘Gwe is fragile’, respectively What if the semantic content of ‘fragile’ is wholly determined by the internal psychological states of the speaker? The semantic content of a dispositional term is constituted by the external environment in which the speaker typically deals with x

10. Gwe is not fragile It is not clear at all what practical purpose it serves for Kim* to attribute fragility to Gwe Surely Gwe would break if struck in the absence of all the wizards surrounding it → Their presence will be part of what the inhabitants of Wizard Earth will take as perfectly ordinary or normal Dispositional concepts are expected to help us deal with x under a typical circumstance where we deal with or have to deal with x

11. Main thesis Conventional dispositions (e.g., fragility, water-solubility, superconductivity, and so on) The semantic content of an individual K’s utterance of ‘x has a conventional disposition D’ is affected by the pervasive features of a circumstance where K is typically expected to deal with x It is impossible that x has a conventional disposition D in K’s idiolect but, if the stimulus condition obtains, it won’t exhibit the characteristic manifestation of D due to the interference by a prevalent feature of a circumstance where K is typically expected to deal with x

12. Intrinsic duplicate reasoning A strong temptation to insist that, despite the prevalence of the wizards on Wizard Earth, Gwe is still fragile regardless of whether it is seen from Kim’s perspective or from Kim*’s perspective Gw has a molecule-to-molecule intrinsic duplicate situated in the absence of the masking wizard → Unquestionably fragile The predicate ‘fragile’ in the present context expresses an intrinsic disposition

13. Gw An unprotected intrinsic duplicate of Gw

14. Gwe An unprotected intrinsic duplicate of Gwe

15. No dialectic force The assumption that ‘fragile’ in the relevant context expresses an intrinsic disposition No justification for the assumption that the unprotected glass is fragile → Begging the question

16. No interference reasoning I An unprotected intrinsic duplicate of Gw that is situated in the absence of the wizard Whether x is fragile or not must be determined by what would happen to it if it were struck in the absence of any external interferences Gw has an appropriate internal structure that makes it the case that Gw would break if struck in the absence of external interferences

17. Gw An unprotected intrinsic duplicate of Gw

18. No interference reasoning II Gw wouldn’t break if struck The internal molecular structure of Gw ensures that, barring the external interference, Gw would indeed break if struck More profound and deeply entrenched than the intrinsic duplicate reasoning An apparent justification for the intrinsic duplicate reasoning

19. Gwe is fragile? Gwe, if struck, would not break as a result of the protective operation of extrinsic factors Gwe has a molecular bonding structure that makes sure that, barring external interferences with the prevalent wizards, it would break if struck The sentence ‘Gwe is fragile’ is true whether it is uttered by Kim or Kim* An unfounded dogma

20. Dispositions and practices We use dispositional concepts to describe counterfactual states of affairs Dispositional ascriptions and counterfactual conditionals Almost every concrete object is involved in indefinitely many counterfactual states of affairs

21. Countless counterfactual states of affairs The glass on my desk would break if struck It would make a distinctive sound if tapped with a wooden spoon It would not emanate a strange smell if heated up to 60 Celsius It would not catch fire if ignited Not all the counterfactual states of affairs obtaining in the world are of practical interest or concern to us in general

22. Conventional dispositions Conventional dispositional concepts have been introduced into our conceptual system to succinctly describe those counterfactual states of affairs which are of special practical significance to us Being much concerned with whether x would cause harm or not if not enough care were taken to deal with it, we have introduced the dispositional concept of danger to distinguish everyday items in term of it and, based upon this distinction, facilitate explaining or predicting their behaviours

23. Ordinary conditions We are most concerned with how to sort things out and explain or predict their behaviours under the conditions that typically obtain when we deal with or need to deal with them Conventional dispositional concepts have to do with what would happen to x under the conditions that obtain when we are routinely expected to handle x Generalization – When it is uttered in a concept community that x is disposed to do A, it means that x is disposed to do A in a typical circumstance where its members commonly deal with or need to deal with x

24. What is wrong? Of no practical interest to Kim* what behaviours Gwe will exhibit in a remotely possible circumstance Conventional dispositional concepts are intended to articulate those counterfactual states of affairs that are of special practical interest to their possessors Kim*’s concept of fragility is expected to do the practical services in the presence of the masking wizards The externalist semantics of dispositional terms