The Deductive Nomological Method with Falsificationism

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A Simplistic view of Scientific Method
In scientific method, we sometimes use inductive generalization to identify causal correlations. One way we can describe the process is:

• The basic view:
  1. We observe (in our sample) that events of kind Q follows events of kind P;
  2. We generalize that Qs always follow Ps (that is, Qs follow Ps throughout our population, which is all events, including future events);
  3. We say that Ps cause Qs.
• There are two problems with the basic view:
  1. Science posits that there is something underlying the correlation of two events which allows us to say that one causes another: the working of natural laws. In other words, not all correlations are taken to be causal.
  2. It is never clear which observations should be made until we have a hypothesis about what correlations we expect (that is, until we have a hypothesis about natural laws).

Deductive Nomological Theory of Science, with Falsificationism
The leading alternative is a more sophisticated view.

• We develop a hypothesis that there are certain natural laws or certain effects of natural laws. These hypotheses must be falsifiable: they must entail predictions which are in principle testable and could be false.
• We predict some events which must occur if our hypothesis is true (that is, what are some unexpected results such laws or effects will have?).
• We check to see if these predictions come true; if they do, we make inductive generalizations based on these observations.
• We continue to try to falsify the view.
• Thus, for example:
  • Suppose H is a hypothesis.
  • We look to see what events H implies.
  • If these predicted phenomena are observed to be true, we continue to hold H as a hypothesis.
  • We especially are inclined to consider H likely if any of these consequences are unexpected.
  • If any of the predicted consequences is observed false, we reject the hypothesis.
• The "deductive" part here is the inference from hypothesis to consequences. The "nomological" part is the presumption that we are aiming to discover laws ("nomological" means reasoning about laws).
• A fantastic example includes Einstein's claims that gravity warps spacetime. This was weird, unexpected, and so the predictions were strange and unexpected.
• Some important corollaries of the deductive nomological theory with falsificationism
  1. We cannot prove a theory, we can only show it is likely.
  2. Thus, we never know a theory is true (although we can show that it is vastly superior to the alternatives, etc.).
  3. Science is creative: you must come up with hypotheses before you can apply scientific method.
  4. A scientific theory (that is, a theory about the physical world, not a logical theory) which is not falsifiable is a bad theory!

Falsificationism
Why does it matter that a scientific theory must be falsifiable?

• What kind of claim is not falsifiable? Examples include:
  • All bachelors are unmarried males.
  • 2+2=4
  Most are inclined to believe that what distinguishes these examples is that they are true either in terms of meaning (analytic) or are consequences of other premises (logical claims).
• A claim that is not falsifiable is typically an analytic claim dressed up to look like a synthetic claim (a substantial claim not just concerned with meaning or logic alone). Even the person making the claim may be confused.
• Example: economists often claim all motivations are selfish. Confronted with the observation that some people appear to do altruistic things, they may say these people desire to do altruistic things and so are selfish. But note: "selfish" on this kind of view means nothing more than something like, does what one wants to do. That is fine -- economists should be allowed to define any terminology they want -- but it is a different meaning than we usually use for "selfish." Furthermore, to say people are "selfish" on this view is not to make a claim -- it is to state an assumption that they make in all their reasoning!
• Unfalsifiable claims are thus usually presumptions, perhaps vacuous, that are dressed up like substantive claims. Typically even the person making the unfalsifiable claim is deceived by their own terminology and misses the ambiguity.