n in calling the X in P2 an X.
             It was stated in the introduction that it was only upon a good understanding of how observation statements are formed and how the relation of concepts in any theory work that will determine whether or not the Quine-Duhem thesis really does throw a spanner in the works for Popper. We need to work out exactly what are the "bold conjectures" and the particular instances that Popper is talking about. For Quine, observation was explained by "observation statements", i.e. the statements that one would utter on all occasions when certain sensory receptors are triggered. This is one way of understanding the "particular instances" that for Popper can refute a universal claim. But a scientific theory is not such a statement. It does not relate to any particular event or object but all objects and instances in a certain category. There is no single observation in the natural world that it corresponds to, if theories are for Popper prior to experienc
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