INTRODUCTION

This chapter begins with a confession. I have, to this point, been taking advantage of the ambiguity of the term theoretical, using it to describe what we can now see to be two quite distinct components of the process of model building. On the one hand, there are ideas about abstract ecological dispositions; on the other, there are the theoretical models we use to articulate those ideas. Both can properly be seen as the domain of the theoretical. But it is important to recognize the distinction because these two readings confront the problem of interpretation, of bringing the theoretical ideas into contact with the empirical realm, in quite distinct ways. This, in turn, becomes important if we are going to resolve the final issue in the grounding of theoretical explanation. How does this business of model building yield invariant counterfactual purchase over the phenomena? How do theories, as explanatory tools, manage to constrain the possibilities? The distinction is also crucial to a second fundamental issue that this chapter addresses: the relationship between truth and explanatory success. With these final two issues confronted, the chapter will return, at last, to the controversies that were identified in Chapter Five as standing in need of deeper philosophical analysis.

TWO SENSES OF THEORETICAL

We begin with the distinction that has just been drawn between the two senses of theoretical. The difference between the two notions is perhaps best seen by looking at the contrast class for each.