Chisholm’s point of view on the problem of the Ship of Theseus

The puzzle: At t’: all the pieces of the original ship in the harbour start being replaced At tn: we have, in the harbour, a renovated ship made up only by new pieces and, in the warehouse, a reconstructed ship, built with all the original pieces. The situation at tn seems to go against the principle of the transitivity of identity: The original ship at t’ is the renovated ship at tn The original ship at t’ is the reconstructed ship at tn For Chisholm the problem is due to an erroneus use of the concept of identity…

The "loose" sense of identity: Bishop Butler: we can speak of the persistence of familiar objects (like ships, plants, houses, etc…) just in a "loose and popular sense", and not in the "strict and philosophical sense" (wich, for him, can be used for persons) Chisholm's definition of loose sense: we use the locution "A is B" or "A is identical to B" in a loose sense, if we use it in such a way that it is consistent with saying "A has a certain proprerty that B does not have" or "some things are true of A that aren't true of B" Do we ever use the locution "A is B" in this loose way? Chisholm find five different uses…

Examples of the uses of the loose sense When we use "is" to identify something with one of its parts ("Route 6 is Point Street in Providence and is Fall River Avenue in Seekonk") When we use "is" referring to a fission ("This train will be two trains after Minneapolis") or a fusion. When we use "is" referring to something exemplified by different entities trough time ("The president of the Italian republic was Napolitano in the 2015 and Mattarella in the 2016) When we use "is" to say that two objects are of the same sort ("That's the same instrument that i play!) "Feigning identity"…

Feigning Identity (Hume; Tomas Reid): Strictly speaking, whenever there is a change of parts, however insignificant the parts may be, then some old thing ceasee to being, and some new thing comes into being. But if, from the point of view of our practical concerns, the new thing that comes to be i sufficiently similar to the old one then it is much more convenient for us to treat them as if they were one. So, when we talk about such things as the Ship oh Theseus or, more generically, most familiar physical things, we are referring to "fictions". They are"logical construction" upon things wich cannot survive the loss of their parts. If Reid is right, then, we can't affirm neither (1) or (2) in a strict and phylosophical sense, cause we are, in both (1) and (2), playing loose with the "is" of identity But could we think of familiar physical things as being logical contructions?

Consider the history of a very simple table: On Monday, it came to be when a certain thing A is joined o a certain thing B. On Tuesday B is detached from A and joint to C, all occurring in such a way that a table can be found in every moment of the process. On Wednesday, B is detached from C, and than C is joint with D, even in this case in a way that a table can always be found during the process. So we have three objects, AB, BC and CD, wich constitute the same table in a "succesion of object". AB constitute the table on Monday, BC do it on Tuesday an CD on Wednesday. Two different type of individual things involved: the ens successivum – the successive table- and the things that do duty for it at different times. Chisholm uses the concept of "table successor" to define the concept of "part"…

Direct table successor (DI): x is at t a direct table successor of y at t' = t does not begin before t'; x is a table at t and y is a table at t'; there is a z, such that z is a part of x at t and a part of y at t', and at every moment between t' and t, inclusive, z is itself a table. Table successor(DII): x is at t a table successor of y at t' = t does not begin before t'; x is a table at t, and y is a table at t'; x has a t every property P such that y has P at t' and all direct table successors of anything having P have P. Following from those two definition: (DIII):x constitutes at t the same successive table that y constitutes at t' = either x and only x is at t a table successor of y at t', or y and only y is at t' a table successor of x at t. (DIV):x constitutes at t a successive table = there are a y and a t' such that y is other than x, and x constitutes at t the same table that y constitutes at t'- (DV):there is exactly one successive table at place P at time t = there is exactly one thing at place P at time t that constitutes a successive table at t These definitions give us proper informations about the successive table and the tables wich constitute it , but what about the properties of the successive table? How are they related to the properties of the objects that constitute it?

Chisholm distinguish three kind of poperties: Properties that can be said to be "rooted outside the time at wich they are had", for example "being a widow" or "being a future president". Properties that may - but need not- be rooted outside the time at wich they are had, for example the property of "being such that it is or was red":our successive table may derive this from its present contituent or from a former one. Properties that can't be said to be rooted outside the time at wich they are had, for example "being red". Those are the properties that the ens successivum borrows from the thing that constitutes it at that time. We can say that, at a given time and with respect to this kind of properties, the ens successivum and the thing that constitutes it are exactly alike.

Possible objection: "You are committed to saying that AB, BC, CD and our table are four different things. It may well be, however, that each of the three things AB, BC, CD satisfies the conditions of any acceptable definition of the term "table". Indeed yor definitions presuppose that each of them is a table. Hence you are committed to saying that, in the situation described, there are four tables. But this is absurd; for actually you have described only one table." But the statement that there are four tables is simply the result of confusion: we have exactly three tables, if we are speacking in the strict and philosophical sense. Instead,speacking in the loose and popular sense, we have exactly on table. Saying that there are four tables, we are mistakenly trying to speak both ways at once.