Sklar's Maneuver
Sklar's Maneuver
Sklar, on page 230, suggests a way to deal with absolute acceleration on the pure relationism.
To maintain the relationist doctrine of space and time in the face of the acceptance of absolute motions, what we must do is deny that the predicate 'is accelerated' is a relational term! The expression 'A is accelerated' is incomplete. To complete it we must answer the question, "Relative to what is A accelarated?" But the expression 'A is absolutely accelerated' is a complete assertion, as is for example, 'A is red', or 'A is bored', and unlike 'A is north of'.
According to this suggestion, absolute acceleration is a property that a system has or does not have, independently of the existence or state of anything else in the world. In other words, Sklar is saying that the relationism does not have to try to explain absolute acceleration in terms of relative motions.
Defenders of absolutism or substantivalism, such as Friedman or Earman, concede at least that this is an ingeneous suggestion, which no one else has thought of. For instance, Friedman (1983, 232) admits that this suggestion can provide a 'third approach', and he sees that 'such a view would fit in very well with the "monadism" of the historical Leibniz' (1983, 233 note), because for Leibniz the force was an internal power, not impressed on and external to the body suffering the force. Earman, who named Sklar's suggestion as "Sklar's Maneuver", partly agrees with Friedman's view on this point, but he thinks that Sklar's maneuver is a 'conjuring trick' (Earman 1989, 214 note 10) , which can achieve at most only a partial realization of its purpose (Earman 1989, 127-8). For the full arguments by Friedman and by Earman, see their own books.
References
Sklar, Lawrence (1976) Space, Time, and Spacetime, University of California Press, 1974 and 1976.
Friedman, Michael (1983) Foundations of Space-Time Theories, Princeton University Press, 1983.
Earman, John (1989) World Enough and Space-Time, MIT Press, 1989.
Last modified March 31, 2003. (c) Soshichi Uchii