Editing New riddle of induction (section)

==Grue and bleen==
[[File:Grue and Bleen (EN).png|thumb|Definitions of ''grue'' and ''bleen'', as well as how the original colors ''blue'' and ''green'' can be redefined based on the two predicates]]
Goodman defined "grue" relative to an arbitrary but fixed time ''t'':{{efn|Historically, Goodman used ''"[[V-E day]]"'' and ''"a certain time t"'' in ''A Query on Confirmation'' (p.&nbsp;383) and ''Fact, fiction, and forecast'' (3rd ed. 1973, p.&nbsp;73), respectively.}} an object is grue [[if and only if]] it is observed before ''t'' and is green, or else is not so observed and is blue. An object is "bleen" if and only if it is observed before ''t'' and is blue, or else is not so observed and is green.<ref>{{cite SEP|title=Nelson Goodman|url-id=goodman|date=Mar 25, 2019}}</ref>

For some arbitrary future time ''t'', say January 1, {{#expr:{{#time:Y}} + 10}}, <!-- The expression gives the current year plus ten, for a date guaranteed to be in the future no matter when this page is retrieved. --> for all green things observed prior to ''t'', such as [[emerald]]s and well-watered grass, both the predicates ''green'' and ''grue'' apply. Likewise for all blue things observed prior to ''t'', such as [[bluebird]]s or [[blue flower]]s, both the predicates ''blue'' and ''bleen'' apply. On January&nbsp;2, {{#expr:{{#time:Y}} + 10}}, however, emeralds and well-watered grass are ''bleen'', and bluebirds or blue flowers are ''grue''. The predicates ''grue'' and ''bleen'' are not the kinds of predicates used in everyday life or in science, but they apply in just the same way as the predicates ''green'' and ''blue'' up until some future time ''t''. From the perspective of observers before time ''t'' it is indeterminate which predicates are future projectible (''green'' and ''blue'' or ''grue'' and ''bleen'').