In my last post, I wrote about a certain kind of inductive argument. Appealing to the authority of a legitimate expert is a common way we construct arguments. All of us rely on this kind of argument to make decisions about all sorts of issues: who to vote for, which charity to contribute to, which movie to see, which book to read, which college to attend, and so on.
For this post, I'm still going to write about inductive reasoning, but I'm going to connect it, as best as I can, to the scientific enterprise. You've probably heard of the Scientific Method before. When considered as a method of reasoning, the Scientific Method is an empirical form of inductive reasoning.
A scientist's curiosity (I guess, given human history, an aspiring scientist's curiosity would be just as dynamic. After all, before Einstein won his Nobel Prize for Physics, he was a Swiss patent clerk wondering what would happen if a person were to travel at the speed of light.) is piqued. Suppose our wondering scientist works as a zoologist at Lincoln Park Zoo.
"I wonder," the scientist might say to herself after watching a late-night showing of Stand by Me, "if non-human mammals can experience "friendship" either within their own species or outside of it?" (This was the subject of a recent episode of Nature. If anyone is interested, here is the link: http://www.pbs.org/wnet/nature/episodes/animal-odd-couples/full-episode/8009/
The zoologist would then go beyond mere wondering. She would create a hypothesis and then create an experiment to test her hypothesis. In the Nature episode, the zoologist closely observed a troop of macaques and then would test their feces for a chemical, I think it was cortisol, that is released when a macaque experiences stress. Thus, there would be two fundamental sets of data for the zoologist to analyze.
The behavior of the macaques, in particular behavior that indicated "friendship" would be one set of data. For example, macaques groom each other. Thus, grooming might indicate "trust" between two macaques.
The level of cortisol would be the second set of data.
Even before the zoologist examines her data sets, she has performed thousands of inductive reasoning chains. Most of these inductive reasoning chains involve the following basic structure:
X has happened repeatedly in the past, thus X will continue to happen in the future e.g.,
-In the past, the sun has always risen in the East; thus the sun will rise in the East tomorrow.
-For the past 10,000 years , the tropical island (I think it was Costa Rica) that the macaques live on has not experienced a blizzard; thus, the tropical island that the macaques will not experience a blizzard during the zoologist's research
-For the past 1000 years, most of the members of a troop of macaques in Costa Rica have not died simultaneously from natural causes; thus, most of the members of the troop of macaques she observes on a Monday will still be alive on Tuesday.
-For as long as macaques have inhabited Costa Rica, they have pooped. Thus, macaques will continue to poop in the future.
-In the past, other scientific research has established beyond a reasonable doubt that cortisol is a chemical that is released by macaques when they experience stress; thus, in the future, when a macaque is experiencing stress, its body will release cortisol.
In the past, other scientific research has establish beyond a reasonable doubt that zoologist's can accurately measure the amount of cortisol in a macaques body, thus in the future, when a zoologist measures the amount of cortisol in a macaques' body it will be accurate.
And so on.
Once the two sets of data have been collected, it will carefully examined. The zoologist will see if a correlation exists between, say, lower levels of cortisol and number of grooming events.
Suppose, for the sake of simplicity, there were a 100 macaques in the troop that our zoologist was observing. Suppose further that the 10 macaques that participated in the most grooming events had much lower levels of cortisol in their bodies. Here the zoologist would produce an inference to explain the data.
1. "During my observations of macaque troop #1, I observed 10,000 grooming events."
2. "For the purposes of my experiment, each "grooming event" will be interpreted as indicating an episode of "monkey-trust" between two macaques."
3. "For the purpose of my experiment, each episode of "monkey-trust" will be interpreted as indicating evidence for a macaque's ability to experience "monkey-friendship."
Assumption 1: "Experiencing less stress gives any mammal an evolutionary advantage to survive and procreate."
Assumption 2: "Monkey-friendship is analogous to human friendship in that it reduces the amount of stress the body produces."
Assumption 3: "If a pair of macaques experience "monkey-friendship," then that pair of macaques will each experience less stress than a macaque that does not experience "monkey-friendship."
Hypothesis 1: "If a pair of macaques experience "monkey-friendship," then each of those macaques will produce lower levels of cortisol than any macaque that does not experience "monkey-friendship."
Hypothesis 2:"If hypothesis 1 is true, then macaques can experience friendship in a way analogous to the way that human's experience friendship."
Conclusion: "The macaques that participated in the most "grooming events" had the lowest levels of cortisol, thus macaques do experience friendship analogously to humans."
Now here things may get a little confusing. In fact, this entire reasoning process as its stated above is deductive. If the premises and the assumptions and the hypothesis are all true, then the conclusion would also be true.
But every one of the premises and assumptions and hypothesis would itself rely on an inductive argument. For example, (2) simply stipulates that "grooming events" will be "interpreted" in a certain way. But why think that "grooming events" should be interpreted in this way? Well, by way of induction, a grooming event would seem to more consonant with an explanation that postulate "trust" than one that postulate "dominance," but no one can be sure this intuitive relationship actually holds.
Thus, the beauty and the curse of inductive reasoning.