A universal proposition is one that affirms a property of all the members of a set. For instance, the proposition that all dogs are mortal and the proposition that all cows can fly are universal propositions, the former (assumedly) true and the latter false. A universal proposition is logically equivalent to the negation of an existential proposition. Thus, claiming that all cows can fly is equivalent to denying that there is a cow that cannot fly. Use of the term The concept of property or ownership has no single or universally accepted definition. ... The notion of a set is one of the most important and fundamental concepts in modern mathematics. ... Trinomial name Canis lupus familiaris The dog is a canine carnivorous mammal that has been domesticated for at least 14,000 years and perhaps for as long as 150,000 years based on recent evidence. ... Wiktionary has a definition of: Cow Cow may refer to: Female cattle, other bovines, or other large mammals including elephants and whales. ... An existential proposition is one that affirms the existence of a member of a collection that possesses a specified property. ...

It may be noted, along the lines of Humean causal scepticism, that the only universal propositions that must be true are those that are extent a priori, drawn from definitions (i.e. "All dogs are mammals"). Universal propositions that are drawn a posteriori, from one's experience of the world (i.e. "All dogs are born with four legs"), can never be confirmed as true, simply supported to be true (though such propositions are falsifiable). David Hume David Hume (April 26, 1711 – August 25, 1776) was a Scottish philosopher and historian and, with Adam Smith and Thomas Reid among others, one of the most important figures in the Scottish Enlightenment. ... A priori is a Latin phrase meaning from the former or less literally before experience. In much of the modern Western tradition, the term a priori is considered to mean propositional knowledge that can be had without, or prior to, experience. ... Empirical or a posteriori knowledge is propositional knowledge obtained by experience. ... This page discusses how a theory or assertion is falsifiable (disprovable opp: verifiable), rather than the non-philosophical use of falsification, meaning counterfeiting. ...