Part I investigates the idea that kinds (as opposed to individuals) have some modal properties. I argue that concerning typical kind-essentialist claims there is a non-trivial question—the transworld identity problem—about what the relevant kind terms are supposed to refer to in non-actual possible worlds. I reject several ideas for solving the problem. The upshot is a worry about the coherence of modal talk concerning kinds. Waiving this worry for the sake of argument, in Part II the target is the use of modal talk in the sciences. I offer a deflationary account of modalities, based on the familiar idea of reducing modalities to logical relationships between non-modal statements and non-modal background theories. I argue that this account is adequate for making sense of modal talk in the sciences. Moreover, I argue that irreducible modal properties of the world, if there are any, cannot be scientifically discovered or inferred. Thus we have a number of arguments against modalities: the threat of incoherence, their epistemic inaccessibility, and the dispensability of modal talk in the sciences.

Part I investigates the idea that kinds (as opposed to individuals) have some modal properties. I argue that concerning typical kind-essentialist claims there is a non-trivial question—the transworld identity problem—about what the relevant kind terms are supposed to refer to in non-actual possible worlds. I reject several ideas for solving the problem. The upshot is a worry about the coherence of modal talk concerning kinds. Waiving this worry for the sake of argument, in Part II the target is the use of modal talk in the sciences. I offer a deflationary account of modalities, based on the familiar idea of reducing modalities to logical relationships between non-modal statements and non-modal background theories. I argue that this account is adequate for making sense of modal talk in the sciences. Moreover, I argue that irreducible modal properties of the world, if there are any, cannot be scientifically discovered or inferred. Thus we have a number of arguments against modalities: the threat of incoherence, their epistemic inaccessibility, and the dispensability of modal talk in the sciences.

De jure and De facto Rigidity in the General Terms for Natural Kinds”. This paper will argue that one of rigidity’s central problems in general terms for natural kinds, is consequence of not distinguishing between de jure rigid terms and de facto rigid terms on these cases. The paper claims that necessary identity sentences defended by Kripke in Naming and Necessity consider the term’s occurrence to designate a same kind (kinds which share the transworld relation of being one same kind) through two rigidity terms, a de jure one, and a de facto one. This allows to explain the problems that arise from the notion of rigidity in the case of general terms for natural kinds, since it maintains the causal connection requirements, while at the same time it enunciates the identity criterion between these kinds, through the essential property(ies) of the abovementioned kind. / En este escrito se argumentará que uno de los problemas centrales de la rigidez en los términos generales para clases naturales es consecuencia de no distinguir entre términos rígidos de jure y términos rígidos de facto en dichos casos. Se sostiene que los enunciados de identidad necesarios defendidos por Kripke en Naming and Necessity consideran la ocurrencia de términos que designan a una misma clase (clases que poseen entre sí la relación transmundana de ser una misma clase) a través de dos términos rígidos, uno de jure y uno de facto. Esto permite explicar los problemas que la noción de rigidez plantea en los casos de los términos generales para clases naturales, pues mantiene los requerimientos de conexión causal y a su vez enuncia el criterio de identidad entre tales clases, a través de la(s) propiedad(es) esencial(es) de dicha clase.