Subjunctive Reasoning

There exists quite a variety of statements which are in some sense 'subjunctive'. The best known of these are the so-called 'counterfactual conditionals' which state that if something which is not the case had been the case, then something else would have been true. An example is 'If Kennedy had been president in 1972, the Watergate scandal would not have occurred'. Ordinary people use counterfactuals all the time, and philosophers use them freely in ordinary situations. However, when they are being careful, philosophers have traditionally felt uncomfortable about counterfactuals and eschewed their employment in philosophical analysis. Such philosophical squeamishness is on the whole meritorious and results from the recognition that counterfactual conditions have themselves stubbornly resisted philosophical analysis.
Although counterfactual conditionals constitute the kind of subjunctive statement which comes most readily to the mind of a philosopher, it is far from being the only philosophically important kind of subjunctive statement. Philosophers have long recognized that laws of nature cannot really be formulated using universally quantified material conditionals, but they have not usually been prepared to go the extra distance of admitting that statements expressing such laws are really subjunctive. It turns out that laws of nature must be formulated using a special kind of subjunctive statement, herein called a 'subjunctive generalization'. Subjunctive generalizations prove to be of pre-eminent importance in discussing inductive confirmation.
Causal statements constitute another category of statements which are in the requisite sense 'subjunctive'. The analysis of causal statements has always been recognized to be an extraordinarily difficult philosophical problem, but I think it has rarely been appreciated that the main source of this difficulty lies in the subjunctive nature of causal statements.
A traditional philosophical problem is the analysis of probability statements. There are in fact a number of different concepts equally deserving of being called 'probability'. There is not just one legitimate concept of probability. Philosophers have succeeded in sorting out and distinguishing between a number of different probability concepts, including 'degree of confirmation', 'degree of belief', 'degree of rational belief', and others. However, there are many probability statements which cannot be formulated using any of these recognized 'indicative' probability concepts. It will turn out that there are some extremely important probability concepts that are in essential ways 'subjunctive' and which have been almost entirely overlooked by philosophers bent upon the avoidance of suspicious (to them) subjunctive reasoning.
A problematic concept which has usually been recognized to have a subjunctive core is that of a disposition. Dispositions constitute an important tool of philosophical analysis. Particularly in the philosophy of mind, philosophers have felt that through the use of dispositions they could clarify the structure of interesting concepts. But, of course, the extent of such clarification has been strictly limited by the apparent need for clarifying dispositions themselves.
These various subjunctive concepts map out areas of what might be called 'subjunctive reasoning'.