#### 3000「同一性」の諸相:不可識別者同一の原理をめぐって

vol.2018, no.69, pp.259-273, 2018

<p>The Principle of the Identity of Indiscernibles (hereafter the PII) states that ifany individuals exactly resemble each other, then they are necessarily identical. Intuitively,the PII seems valid, but Max Black attempted to refute it by introducingthe possibility of a symmetry universe in which two iron spheres <i>c</i> and <i>p</i> can resembleeach other exactly. This counterexample (hereafter BU) seems easy to ruleout using a weak discernibility strategy (hereafter WD) according to which <i>c</i>, beingspatially separate from <i>p</i> and not from <i>c</i> itself, is not indiscernible from <i>p</i>. WD, however,leads to 'the presupposition problem', because obtaining <i>c</i> as spatially separatefrom <i>p</i> presupposes the distinctness of <i>c</i> and <i>p</i>. In this discussion, I will give an outlineof a defense of the validity of the PII that evades the presupposition problemthrough the elucidation of some aspects of 'identity'.</p><p>In my view, 'identity' has two aspects: one is simply self-identity as a universalmonadic property (hereafter identity-1), and the other is identity as an equivalencerelation entailing indiscernibility (hereafter identity-2). The basis or ground for identity-1obtaining with regard to an individual <i>x</i> can be called the individuator for <i>x</i>,but it is no wonder that the individuation and articulation of <i>c</i> and <i>p</i> are prior to orground for obtaining <i>c</i> as spatially separate from <i>p</i>. So far as the PII is concernedwith identity-1, it may not be valid. However, we can characterize identity-2, followingDavid Wiggins's lead, in terms of what is called the sortal dependency of identity-2and the extended Locke's Principle (hereafter ELP), according to which, for anysortal concept <i>F</i>, <i>x</i> falling under <i>F</i> is identical with <i>y</i> falling under <i>F</i> if and only if <i>x</i>is the same <i>F</i> as <i>y</i>, and <i>x</i> is the same <i>F</i> as <i>y</i> if and only if a) <i>x</i> and <i>y</i> share <i>F</i> and b) <i>x</i>is not spatially separate from <i>y</i>. If ELP is valid, we can regard BU as merely a generalcase to which WD is applied. And if the Wigginsian idea of the sortal dependencyof identity-2 is also right, there is no longer a presupposition problem. I hence conclude that the PII is valid to the extent that it is concerned with identity-2.</p>

#### 3000同一性の相対主義の可能性と限界:―意味論と存在論の観点から―

vol.51, no.1, pp.1-17, 2018

<p>&nbsp;&nbsp;&nbsp;&nbsp;The aim of this paper is twofold. The one is to make intelligible identity-relativism (IR) and its accompanying theory of proper names by making amendments to Peter Geach's corresponding theories. I argue that his IR can be reconstructed as a hidden variable theory of 'identical' and that a kind of ontological deflationism is needed to make his semantics of proper names compatible with IR. The other aim is to show that even IR with the seemingly refined semantics and ontology bears a serious problem of the requirement for an absolute identity. I argue that IR cannot by itself solve the problem.</p>

#### 3000IR絶対か相対か : 同一性と種別概念の結び付きをめぐって

vol.137, pp.115-143, 2016-03

#### 2200OA蝶名林亮編著『メタ倫理学の最前線』

The Philosophy of Science Society, Japan

vol.53, no.1, pp.103-108, 2020-09-30 (Released:2020-09-30)

#### 2000OA「同一性」の諸相 不可識別者同一の原理をめぐって

vol.2018, no.69, pp.259-273, 2018-04-01 (Released:2018-08-01)

26

The Principle of the Identity of Indiscernibles (hereafter the PII) states that if any individuals exactly resemble each other, then they are necessarily identical. Intuitively, the PII seems valid, but Max Black attempted to refute it by introducing the possibility of a symmetry universe in which two iron spheres c and p can resemble each other exactly. This counterexample (hereafter BU) seems easy to rule out using a weak discernibility strategy (hereafter WD) according to which c, being spatially separate from p and not from c itself, is not indiscernible from p. WD, however, leads to ‘the presupposition problem’, because obtaining c as spatially separate from p presupposes the distinctness of c and p. In this discussion, I will give an outline of a defense of the validity of the PII that evades the presupposition problem through the elucidation of some aspects of ‘identity’. In my view, ‘identity’ has two aspects: one is simply self-identity as a universal monadic property (hereafter identity-1), and the other is identity as an equivalence relation entailing indiscernibility (hereafter identity-2). The basis or ground for identity-1 obtaining with regard to an individual x can be called the individuator for x, but it is no wonder that the individuation and articulation of c and p are prior to or ground for obtaining c as spatially separate from p. So far as the PII is concerned with identity-1, it may not be valid. However, we can characterize identity-2, following David Wiggins’s lead, in terms of what is called the sortal dependency of identity-2 and the extended Locke’s Principle (hereafter ELP), according to which, for any sortal concept F, x falling under F is identical with y falling under F if and only if x is the same F as y, and x is the same F as y if and only if a) x and y share F and b) x is not spatially separate from y. If ELP is valid, we can regard BU as merely a general case to which WD is applied. And if the Wigginsian idea of the sortal dependency of identity-2 is also right, there is no longer a presupposition problem. I hence conclude that the PII is valid to the extent that it is concerned with identity-2.

#### 1000OA同一性の相対主義の可能性と限界

The Philosophy of Science Society, Japan

vol.51, no.1, pp.1-17, 2018-07-31 (Released:2019-05-02)

26

The aim of this paper is twofold. The one is to make intelligible identity-relativism (IR) and its accompanying theory of proper names by making amendments to Peter Geach's corresponding theories. I argue that his IR can be reconstructed as a hidden variable theory of ‘identical' and that a kind of ontological deflationism is needed to make his semantics of proper names compatible with IR. The other aim is to show that even IR with the seemingly refined semantics and ontology bears a serious problem of the requirement for an absolute identity. I argue that IR cannot by itself solve the problem.