Scientific Baselines and Scientific Disagreement: The uniqueness thesis is the view that a given body of evidence supports at most one rational doxastic attitude toward a given proposition – e.g., belief, disbelief or suspension of judgment. In the epistemological literature on disagreement, many are growing to doubt the uniqueness thesis. Some even argue that for any given body of evidence E and any two hypotheses h1 and h2, there is no unique evidential favoring relation such that E supports h1 over h2 (or vice versa). If this latter claim is true, then that would mean that two scientists carefully considering the same evidence could rationally come to different conclusions about which of the two incompatible hypotheses the evidence supports. That would falsify the claim that the sciences are evidence-driven disciplines. I hope to defend the thesis that there can be a unique evidential favoring relation, but only if both hypotheses assume the same natural state model. Unfortunately, of course, the contrapositive of that claim also holds. What is equally unfortunate is that uniqueness also fails at the level of natural state models, which should not be too surprising given that such models are untestable. However, I want to consider the possibility that our choice of natural state models might be uniquely determined by pragmatic reasons related to our scientific goals. This is an area of on-going research, which I hope will lead to the development of a framework that can be used to discover which natural state models best meet our scientific goals. The Contexts of Discovery and Justification: Philosophers of science typically make a distinction between the contexts of discovery and justification. According to the prevailing characterization of that distinction, it is within the context of discovery that a scientist comes up with a new theory. Furthermore, it was thought (amongst the positivists) that activity within that context could not be governed by any normative constraints. The context of justification, on the other hand, was thought to be subject to at least rational constraints, and it is within that context that new theories are empirically tested. Philosophers of science are not as willing (now) to claim that the context of discovery is not governed by any norms, but little has been said about what sorts of norms do govern the context of discovery.