Editing Philosophy of science (section)

===Justifying science===
{{Main|Problem of induction}}

Although it is often taken for granted, it is not at all clear how one can infer the validity of a general statement from a number of specific instances or infer the truth of a theory from a series of successful tests.<ref name="StanInduction">{{cite web|url = http://plato.stanford.edu/entries/induction-problem/|title = The Problem of Induction|access-date = 2014-02-25|last1 = Vickers|first1 = John|year = 2013|website = Stanford Encyclopedia of Philosophy|archive-url = https://web.archive.org/web/20140407014814/http://plato.stanford.edu/entries/induction-problem/|archive-date = 2014-04-07|url-status = live}}</ref> For example, a chicken observes that each morning the farmer comes and gives it food, for hundreds of days in a row. The chicken may therefore use [[inductive reasoning]] to infer that the farmer will bring food ''every'' morning. However, one morning, the farmer comes and kills the chicken. How is scientific reasoning more trustworthy than the chicken's reasoning?

One approach is to acknowledge that induction cannot achieve certainty, but observing more instances of a general statement can at least make the general statement more [[Probability|probable]]. So the chicken would be right to conclude from all those mornings that it is likely the farmer will come with food again the next morning, even if it cannot be certain. However, there remain difficult questions about the process of interpreting any given evidence into a probability that the general statement is true. One way out of these particular difficulties is to declare that all beliefs about scientific theories are [[Bayesian probability|subjective]], or personal, and correct reasoning is merely about how evidence should change one's subjective beliefs over time.<ref name=StanInduction/>

Some argue that what scientists do is not inductive reasoning at all but rather [[abductive reasoning]], or inference to the best explanation. In this account, science is not about generalizing specific instances but rather about hypothesizing explanations for what is observed. As discussed in the previous section, it is not always clear what is meant by the "best explanation". [[Ockham's razor]], which counsels choosing the [[Simplicity|simplest]] available explanation, thus plays an important role in some versions of this approach. To return to the example of the chicken, would it be simpler to suppose that the farmer cares about it and will continue taking care of it indefinitely or that the farmer is fattening it up for slaughter? Philosophers have tried to make this [[heuristic]] principle more precise regarding theoretical [[Occam's razor|parsimony]] or other measures. Yet, although various measures of simplicity have been brought forward as potential candidates, it is generally accepted that there is no such thing as a theory-independent measure of simplicity. In other words, there appear to be as many different measures of simplicity as there are theories themselves, and the task of choosing between measures of simplicity appears to be every bit as problematic as the job of choosing between theories.<ref name="StanSimple">{{cite web|url = http://plato.stanford.edu/entries/simplicity/|title = Simplicity|access-date = 2014-02-25|last1 = Baker|first1 = Alan|year = 2013|website = Stanford Encyclopedia of Philosophy|archive-url = https://web.archive.org/web/20140326180129/http://plato.stanford.edu/entries/simplicity/|archive-date = 2014-03-26|url-status = live}}</ref> [[Nicholas Maxwell]] has argued for some decades that unity rather than simplicity is the key non-empirical factor in influencing the choice of theory in science, persistent preference for unified theories in effect committing science to the acceptance of a metaphysical thesis concerning unity in nature. In order to improve this problematic thesis, it needs to be represented in the form of a hierarchy of theses, each thesis becoming more insubstantial as one goes up the hierarchy.<ref>[[Nicholas Maxwell]] (1998) [https://global.oup.com/academic/product/the-comprehensibility-of-the-universe-9780199261550?lang=en&cc=gb The Comprehensibility of the Universe] {{Webarchive|url=https://web.archive.org/web/20180227214410/https://global.oup.com/academic/product/the-comprehensibility-of-the-universe-9780199261550?lang=en&cc=gb |date=2018-02-27 }} Clarendon Press; (2017) [http://www.paragonhouse.com/xcart/Understanding-Scientific-Progress-Aim-Oriented-Empiricism.html Understanding Scientific Progress: Aim-Oriented Empiricism] {{Webarchive|url=https://web.archive.org/web/20180220210819/http://www.paragonhouse.com/xcart/Understanding-Scientific-Progress-Aim-Oriented-Empiricism.html |date=2018-02-20 }}, Paragon House, St. Paul</ref>