The existence of an ideological element in each science has caused some representatives of the sociology of knowledge to deny the objective validity of scientific statements, particularly in the domain of the social sciences. Such a conclusion is unwarranted. The validity of scientific statements can be ascertained with impersonal objectivity through an appeal to facts. Predictions derived from scientific statements are or are not borne out under the test of verification. The outcome is entirely independent of human motivations, conscious or subconscious; it depends entirely on the correctness of the scientific procedure applied in establishing the statements.

Facts are verified information that is then presented as objective reality. The rub here is the verified part. How do you verify verified? Facts are slippery, and so is verification. Today's verification may not be tomorrow's. It turns out that facts may not really be facts; they can change as the verification changes; they may only tell part of the story, not the whole story; or they may be so qualified by verifiers that they're empty of information.

Every sentence in order to have definite scientific meaning must be practically or at least theoretically verifiable as either true or false upon the basis of experimental measurements either practically or theoretically obtainable by carrying out a definite and previously specified operation in the future. The meaning of such a sentence is the method of its verification.

Verified facts don't always come pure, but with qualifiers. My warning radar always goes on alert when qualifiers are attached to facts. Qualifiers like: My best judgement... I think... As best I can tell... Usually reliable sources say... For the most part... We've been told... and the like. I don't dismiss facts so qualified; but I'm cautious about taking them to the bank.

Most grown-up people get rid of the childish notion that whatever appears in print is true, but many cling to the equally absurd notion that the printing of a statement does give it some claim to dignity and credence. For the purposes of argumentation, let us here make this point emphatic: The mere fact that a statement appears in print lends not one atom to its value. Every assertion that is brought forward — though it may have been printed a thousand times and repeated a million times — must be challenged and tested before it can be regarded as trustworthy testimony of authority, — before it can be of any value as evidence.

The criterion of truth is that it works even if nobody is prepared to acknowledge it.

Only on the assumption of belief in the validity of values is the attempt to espouse value-judgments meaningful. However, to judge the validity of such values is a matter of faith.

In so far as a scientific statement speaks about reality, it must be falsifiable: and in so far as it is not falsifiable, it does not speak about reality.

Every genuine test of a theory is an attempt to falsify it, or to refute it. Testability is falsifiability; but there are degrees of testabilty: some theories are more testable, more exposed to refutation, than others; they take, as it were, greater risks.

where evidence is erased, narcissism flourishes. The demand for evidence — or validity claims — which has always anchored genuine and progressive science, simply means that one’s own ego cannot impose on the universe a view of reality that finds no support from the universe itself. The validity claims and evidence are the ways in which we attune ourselves to the Kosmos. The validity claims force us to confront reality; they curb our egoic fantasies and self-centered ways; they demand evidence from the rest of the Kosmos; they force us outside of ourselves! They are the checks and balances in the Kosmic Constitution.

(Coining the phrase ‘test of significance’): Critical tests of this kind may be called tests of significance, and when such tests are available we may discover whether a second sample is or is not significantly different from the first.

In affirming that "what is true is the sign of itself and of what is false", Spinoza avoided any problematic which depended on a "criterion of truth ". If you claim to judge the truth of something by some "criterion", you face the problem of the criterion of this criterion -- since it also must be true -- and so on to infinity. Whether the criterion is external (relation of adequacy between mind and thing, in the Aristotelian tradition) or internal (Cartesian self-evidence), in either case the criterion can be rejected: for it only represents a form of Jurisdiction, a Judge to authenticate and guarantee the validity of what is True. And at the same time Spinoza avoids the temptation of talking about the Truth: as a good nominalist (nominalism, as Marx recognized, could then be the antechamber of materialism) Spinoza only talks about what is "true". In fact the idea of Truth and the idea of the Jurisdiction of a Criterion always go together, because the function of the criterion is to identify the Truth of what is true. Once he has set aside the (idealist) temptations of a theory of knowledge, Spinoza then says that "what is true" "identifies itself", not as a Presence but as a Product, in the double sense of the term "product" (result of the work of a process which "discovers" it), as it emerges in its own production. Now this position is not unrelated to the "criterion of practice", a major thesis of Marxist philosophy: for this Marxist "criterion" is not exterior but interior to practice, and since this practice is a process (Lenin insisted on this: practice is not an absolute "criterion" -- only the process is conclusive) the criterion is no form of Jurisdiction; items of knowledge [connaissances ] emerge in the process of their production. There again, by the contrast between them, Spinoza allows us to perceive Hegel's mistake.

Secondly, even disregarding the intrinsic necessity of some new axiom, and even in case it has no intrinsic necessity at all, a probable decision about its truth is possible also in another way, namely, inductively by studying its "success." Success here means fruitfulness in consequences, in particular in "verifiable" consequences, i.e. consequences verifiable without the new axiom, whose proofs with the help of the new axiom, however, are considerably simpler and easier to discover, and make it possible to contract into one proof many different proofs. The axioms for the system of real numbers, rejected by the intuitionists, have in this sense been verified to some extent, owing to the fact that analytic number theory frequently allows one to prove number-theoretical theorems which, in a more cumbersome way, can subsequently be verified by elementary methods. A much higher degree of verification than that, however, is conceivable. There might exists axioms so abundant in their verifiable consequences, shedding so much light upon a whole field, and yielding such powerful methods for solving problems, (and even solving them constructively, as far as that is possible) that, no matter whether or not they are intrinsically necessary, they would have to be accepted at least in the same sense as any well-established physical theory.

In short, for everyone engaged in scientific discourse, statements must be subject to validation by methods and criteria which are, in principle, not subject to partisanship, whatever their ideological consequences, and however motivated. Statements not subject to such validation may nevertheless be important and valuable, but belong to a different order of discourse. They pose extremely interesting and difficult philosophical problems, especially when they are clearly in some sense descriptive (for example, in representative art or criticism 'about' some specific creative work or artist), but cannot be considered here. Nor can we here consider statements of the logico-mathematical type, insofar as they are not (as in theoretical physics) linked to validation by evidence.