MODAL EPISTEMOLOGY

Thesis Statement

Modal epistemology tends to understand how knowledge of modal propositions; propositions of forms necessarily p or possibly p be acquired. But there is a distinctive question about knowledge of modal propositions since our ordinary methods for gaining knowledge: perception, inference, memory, and introspection, seem to give us no non-trivial modal knowledge. (Trivial modal knowledge refers to cases where by knowing p, we can infer ‘possibly p’).

Thesis Development

Modal knowledge include all propositions with the form necessarily p and impossibly p, and also, instances of possibly p that cannot be inferred from knowledge of p itself. Thus, the standard methods of knowledge acquisition only inform us of what is or is not the case. But, they are silent about what must be and what might have been but is not. So, if (non-trivial) modal knowledge is possible, if we are not to be modal sceptics, then some further account must be given of how knowledge of modal propositions is attainable.

Historically, the main view of how we can gain modal knowledge is that there has been a connection between modal facts and some sort of mental activity (conceiving, imagining, and intuiting). At its most programmatic, the view can be expressed by the principle: CP and if it is conceivable that p, then it is possible that p. This applies to a multitude of distinct views whose variations occur chiefly along three dimensions: (1) the nature of the relevant mental state or activity here referred to generically as conceiving; (2) the strength of the connection between conceivability and possibility, here expressed as an unqualified conditional; and (3) the ground of the connection between conceivability and possibility.

Simon Jonah Evinne examines the views of Yablo and Chalmer on conceivability and possibility and adds that p is conceivable only if one can imagine a world that one takes to verify p (CON). He is of the view that the degree of strength in the connection between conceivability and possibility is clearly allowed to be more than a reliable indication. Often, when someone seems to have conceived of an impossibility it will be revealed on further examination either he/she has failed to conceive anything, or that he/she has conceived of something, but not the alleged impossibility. Nonetheless, according to Yablo, modal error is possible if one can genuinely conceive of impossibilities. Jonah adds that there are three ways of understanding CP. Firstly, to acknowledge the fact that the connection between conceivability and possibility is fallible. Secondly, to deny that negations of necessary a posteriori truths are conceivable. And thirdly, to pose that at least in some sense it is possible.

Like Chalmer, Jonah in defence of CP employed a method known as two-dimensionalism, by using the concepts of primary and secondary conceivability. He gave an example that: Hesperus and Phosphorus are the same thing, but was believed initially to be distinct from each other before it was later discovered that they are all the same thing. Hesperus being distinct from Phosphorus is primarily conceivable and primarily possible, but not secondarily conceivable or secondarily possible. And (one of) Chalmers’s preferred precisification(s) of CP is that ideal primary conceivability entails primary possibility.

            More so, Jonah talks about the conventionalism of necessity of which the basic idea is that necessity should be explained in terms of analyticity (truth in virtue of meaning) which, in turn, is accounted for by the existence of conventions or rules about how to use language. Necessity is thus, according to conventionalism, a purely linguistic phenomenon and our knowledge of it derives from our knowledge of the conventions that govern our use of language. Consider the classic example, ‘all bachelors are unmarried’. The conventionalist argues that this sentence is analytic because there exists a rule, or convention, that the word ‘bachelor’ should not be applied to anyone who is married. If we know of the existence of this convention, then we know that not only is ‘all bachelors are unmarried’ true; so is ‘necessarily, all bachelors are unmarried’. Knowledge of necessities, on the conventionalist view, thus turns on knowledge of linguistic conventions.

Finally, Jonah discussed Structural Possibilities and for him plenitude comes in several different forms. One form it takes is as a principle of recombination. The basis for this principle is Lewis’s commitment to a Humean view that nothing logically depends for its existence on the existence of any distinct thing. This leads to a mix-and-match extravaganza in which for any two possible things, it is possible for them to co-exist. Of course, this tells us nothing about which things are possible in the first place; it simply allows us to recombine things that is, the possibility of which we know further possibilities. Thus, if it is possible that a dragon exists and possible that a talking donkey exists, then it is possible that there co-exist a dragon and a talking donkey. However, it also allows us to subtract possibilities. If my cat has a distinct existence from everything else that actually exists (except her parts), then recombination assures me the possibility that my cat might not exist while everything else does. Consequently, Lewisian approach to epistemology of modality does not tell us anything about what is possible absolutely. Instead, what it does is to extend our knowledge of what is possible, given the possibility of certain other things. From this, by recombination, we can infer the possibility of a creature with a dog’s body and a cat’s head.

Questions

Since modal knowledge include all propositions with the form necessarily p and impossibly p, and also, instances of possibly p that cannot be inferred from knowledge, how then do we obtain knowledge from vague inferences? Is modal knowledge a possibilia? How is modal error possible? Is it just from conceiving impossibilities? What has CP to say about metaphysical and supernatural knowledge? Can there be possible and absolute knowledge? Is recombination applicable to all forms of possibilities?

Conclusion

Gaining modal knowledge is something that goes beyond our ordinary methods for gaining knowledge – perception, inference, memory, and introspection this is because they seem to give us no non-trivial modal knowledge. Jonah has offered many other ways of gaining modal knowledge, and has discussed in details, the relationship between conceivability and possibility. From the discussion, we can see that modal knowledge goes with conceivability, and mere conceivability doesn’t entail possibility, there is more to conceivability before it can entail possibility. And thus, our knowledge of a particular thing can give us more knowledge of the possibility of other things.