"valid principle" is correct and usable in written English.
You can use it to refer to a principle or rule that is sound, reasonable, and justifiable. For example, "The valid principle of equality should be respected by all citizens."
From the preceding discussion it is apparent that there is only one universally valid principle of textual criticism, the formulation of which can be traced back at least as far as the 18th-century German historian A.L. von Schlözer: that each case is special.
The Stoics took the universally valid principle of bivalence to imply the predetermination of all future events.
Conditional non-contradiction fails, however, to be a valid principle in the semantics suggested by Stalnaker (1968) and Lewis (1973), cf. the discussion in Unterhuber 2013.
If some valid principle of equality applies directly to health, and if some independent injustices function as causes of health inequalities, then a complete account of justice in relation to health inequalities will require a combined approach.
The reason is that both Wajsberg and Parry derived in system S3 – in its 1918 axiomatization – the following theorem: (p⇒q)⇒((q⇒r)⇒(p⇒r)), which according to Lewis ought not to be regarded as a valid principle of deduction.
Although it is classically valid, Brouwer's proof of the principle shows that the reason for accepting it as a valid principle in intuitionism differs fundamentally from the argument supporting its acceptability in classical mathematics.
Ranke dismissed abstract, universally valid principles as requirements for the establishment of social and national order; he felt that social and political principles must vary according to the characteristics of different peoples.
They sought to discover and act upon universally valid principles governing nature, humanity, and society, including the inalienable "rights of Man," which they treated as a fundamental ethical and social gospel.
Insofar as it aims at directing and guiding human action in all of the fields in which value judgments occur, philosophy is no longer conceived as the search for self-evident, necessary, universally and eternally valid principles but, rather, as the structuring of common principles, values, and loci, accepted by what the philosopher sees as the universal audience.
He seeks universally valid principles (or maxims) of duty, and beneficence is one such principle.
In the recent AO book on nonunions, these are listed as still valid principles [32].
