Research by Dr. Masahiro Yamada


For a list of my publications, please look at my faculty home page.


My area of specialization is epistemology including related areas in the philosophy of mind, language and metaphysics. My other interests include phenomenology and history of philosophy, especially Aristotle's views on change and biology.



My current research interests center around the desire to understand more deeply what we are and how we are related to the world. We think and we act. These are not two independent features of ours. Our thoughts affect our actions – for example, our plans for the future affect what we do now – and our actions affect our thoughts – for example, social institutions are created and maintained by our actions and the existence of these institutions affect our plans. An essential feature of thoughts and actions is that they can be evaluated normatively: thoughts, or trains of thought, can be more or less reasonable; similarly actions, or courses of action, can be more or less reasonable. Since these are essential features of thoughts and actions, we cannot understand what thoughts and actions are without engaging in the normative inquiries required for understanding what reasonable thoughts and actions are. These quick observations open up four areas of investigations:

Action Theory: What is it to act? We do not think that a bouncing ball is engaged in action in the way humans are typically engaged in actions. What is the difference? Is it necessary to be able to think in order to be able to act? These are some of the questions raised in action theory. My current interests in action theory more narrowly focus on a particular type of action: rule following. Following rules is a kind of regularity but it is different from the type of regularity that is displayed by a bouncing ball. What makes it the case that people are following rules when they obey the law but balls are not when they ‘obey’ the laws of physics? Understanding rule following is crucial for understanding ourselves because we are rule following creatures: language, manners and laws are all examples of rule following that loom extremely large in our existence. As part of my dissertation, I sketched a theory of rule following that can avoid some of the problems pointed out by Wittgenstein and Kripke. I hope to develop the sketch further.

Theory of Concepts: What is it to be able to think? Might it be that features of the environment constrain the possible contents of our thoughts? Many philosophers nowadays hold that we could not have thoughts concerning substances like water, gold or oxygen if we were not in some kind of causal contact with these substances. One difficulty with this view is the apparent possibility of error in our thoughts: it seems possible to erroneously believe that there is a substance like oxygen when there is none – after all, some scientists used to believe in phlogiston, a non-existent substance. I am currently working on a view which treats the ability to think as a special case of rule following and that does allow for the environment to constrain what we can think at all and yet at the same time allows for the possibility of going radically wrong about our environment.

Epistemology: This is the central area of my interests. The main question that interests me now is how to formulate a theory of rationality that respects the intuition that a reasonable way of answering a question is also a way that is likely to lead to the correct answer. The perceived problem is that one can go radically wrong while being completely reasonable – for instance, when one is plugged into the Matrix – so that a reasonable way of answering questions need not lead to the correct answer. But can it still be the case that it is likely, though not guaranteed, to lead to the correct answer? In my dissertation I developed a theory that treats rational belief formation as a case of following certain rules of judgment. Careful attention to features of rule following can, I argue, accommodate the basic intuition in the case of analytic reasoning and reliance on basic cognitive faculties like perception. I am currently working on extending this theory to the case of inductive reasoning.

Ethics/Meta-Ethics: Which actions make sense? Some actions make no sense even if they are understandable: think of shooting the messenger. We are interested in what makes sense – or is reasonable – rather than what is understandable. What is it about actions that make them sensible or not? As many philosophers have pointed out, our ordinary intuitions about what makes sense and what does not – or what is right and what is not – are of a character that make them look like rules. If they are rules to be followed, it is perhaps possible to develop a theory of rationality that can unify the theory of rational action and the theory of rational thought. This is the big philosophical pie in the sky that I hope to pursue in more detail.

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