I argued in my last post and in the lively discussion in the comments that evidence has a wider variety of epistemic functions that is commonly appreciated and that those epistemic functions are not reducible to the "support" function. In other words, I want to characterize the essential features of inquiry not as an attempt to gather information that confirms or contradicts some theory of hypothesis, but rather as a complex, multi-phase, multi-directional set of interactions between evidence and theory, as well as problem-statement and other elements.
To be clear, I'm defining evidence in a very broad way: observationally or experimentally generated information about empirical particulars, including not only "raw data" but also models of data, basic interpretations of the data, and even rather generic statements about the phenomena. What I don't mean is what Greg Frost-Arnold suggested in his comment: that we reserve "evidence" for that set of data or information which is settled at the end of an inquiry as figuring in the "support" relation. That is, Greg suggested a dichotomy between "data," which serves all the complex roles I'm interested in, and "evidence," which is the end-product serving the traditional "support" role. While we can go far on this amendment to my argument, I don't ultimately accept it. A basic part of the problem is that philosophers tend to cut off the product from the process and then focus exclusively on the former. This is one of the cases where I think the best way to avoid the strategy is to insist that the product cannot be treated independently. Thus, the broader sense of evidence.
One forceful objection to my view (pressed especially by Thomas and Gabriele Contessa in comments) is that the only way evidence could serve any other function is derivative on and reducible to its function of supporting. Let's focus on my claim that evidence not only supports hypotheses but also suggests them. I think this works in the following way: the inquirer, faced with a problematic situation, surveys the preliminary evidence, which allows them to generate first an attempt to state the problem to be investigated and subsequently a hypothesis for solving the problem. In scientific inquiry, the ability to suggest hypotheses worth investigating further depends heavily on training and "tacit knowledge," but it is, I think, just as essential in naive, commonsense inquiry.
Let's look at some examples:
Consider a child attempting to grow flowers in a flower bed. She's rather upset by the fact that some of the flowers aren't growing very well, while those in a small part of the bed are growing rather well. Looking carefully at the garden during the day, she notices that the small part of the garden with healthy flowers gets full sunlight, whereas the other parts are shaded by the fence or a nearby tree. This suggests to her that maybe the difference is due to the amount of sunlight the plants receive. (Probably the initial observations suggest several other hypotheses as well, but she decides to choose this one.) Now, in order to really support her hypothesis, she'll have to do an experiment. . . .
A case from John Dewey's How We Think (1910) of inquiry involving an experiment:
In washing tumblers in hot soapsuds and placing them mouth downward on a plate, bubbles appeared on the outside of the mouth of the tumblers and then went inside. Why? The presence of bubbles suggests air, which I note must come from inside the tumbler. I see that the soapy water on the plate prevents escape of the air save as it may be caught in bubbles. But why should air leave the tumbler? There was no substance entering to force it out. It must have expanded. It expands by increase of heat or by decrease of pressure, or by both. Could the air have become heated after the tumbler was taken from the hot suds ? Clearly not the air that was already entangled in the water. If heated air was the cause, cold air must have entered in transferring the tumblers from the suds to the plate. I test to see if this supposition is true by taking several more tumblers out. Some I shake so as to make sure of entrapping cold air in them. Some I take out holding mouth downward in order to prevent cold air from entering. Bubbles appear on the outside of every one of the former and on none of the latter. I must be right in my inference. Air from the outside must have been expanded by the heat of the tumbler, which explains the appearance of the bubbles on the outside. . . . (pp. 70-71, emphasis added)
- A case from John Snow's work on cholera in the 19th Century: various kinds of evidence has shown that the effluvial hypothesis for the transmission of the disease was unworkable. From reports and his observation of cholera patients, Snow saw that the pathology of the disease began with intestinal symptoms, rather than symptoms of systematic infection such as fever. This suggested the hypothesis that some morbid material ejected from sick patients was subsequently ingested by those who became infected (and several of the histories of Snow describe it in just this way, that the pathology along with other facts suggested the hypothesis about transmission). Snow then went on to support hist hypothesis by certain epidemiological evidence. . . .