Editing Falsifiability (section)

===Basic statements===

In Popper's view of science, statements of observation can be analyzed within a logical structure independently of any factual observations.<ref name="fourlinesoftesting" group=upper-alpha/><ref name="poppernoapriori" group=upper-alpha /> The set of all purely logical observations that are considered constitutes the empirical basis. Popper calls them the ''basic statements'' or ''test statements''. They are the statements that can be used to show the falsifiability of a theory. Popper says that basic statements do not have to be possible in practice. It is sufficient that they are accepted by convention as belonging to the empirical language, a language that allows [[intersubjective verifiability]]: "they must be testable by intersubjective observation (the material requirement)".{{sfn|Shea|2020|loc=[https://iep.utm.edu/pop-sci/#SH2c Sec. 2.c]}}<ref name="keuthbasicstatementsdependontechnology" group=upper-alpha /> See the examples in section {{slink||Examples of demarcation and applications}}.

In more than twelve pages of ''The Logic of Scientific Discovery'',{{sfn|Popper|1959|loc=sec. 13–15, 28}} Popper discusses informally which statements among those that are considered in the logical structure are basic statements. A logical structure uses universal classes to define laws. For example, in the law "all swans are white" the concept of swans is a universal class. It corresponds to a set of properties that every swan must have. It is not restricted to the swans that exist, existed or will exist. Informally, a basic statement is simply a statement that concerns only a finite number of specific instances in universal classes. In particular, an existential statement such as "there exists a black swan" is not a basic statement, because it is not specific about the instance. On the other hand, "this swan here is black" is a basic statement. Popper says that it is a singular existential statement or simply a singular statement. So, basic statements are singular (existential) statements.