footnote numbers taken over from part 1.
Not Facts but Verisimilitude:
Karl Popper (1902-1994) is one of the most renewed and highly respected figures in the philosophy of science. Popper was from Vienna, of Jewish origin, maintained a youthful flirtation with Marxism, and left his native land due to the rise of Nazism in the late thirties. He is considered to be among the ranks of the greatest philosophers of the twentieth century. Popper is highly respected by scientists in a way that most philosophers of science are not.
He was also a social and political philosopher of considerable stature, a self-professed ‘critical-rationalist’, a dedicated opponent of all forms of scepticism, conventionalism, and relativism in science and in human affairs generally, a committed advocate and staunch defender of the ‘Open Society’, and an implacable critic of totalitarianism in all of its forms. One of the many remarkable features of Popper's thought is the scope of his intellectual influence. In the modern technological and highly-specialised world scientists are rarely aware of the work of philosophers; it is virtually unprecedented to find them queuing up, as they have done in Popper's case, to testify to the enormously practical beneficial impact which that philosophical work has had upon their own. But notwithstanding the fact that he wrote on even the most technical matters with consummate clarity, the scope of Popper's work is such that it is commonplace by now to find that commentators tend to deal with the epistemological, scientific and social elements of his thought as if they were quite disparate and unconnected, and thus the fundamental unity of his philosophical vision and method has to a large degree been dissipated.
Unfortunately for our purposes we will only be able to skim the surface of Popper’s thoughts on the most crucial aspect of this theory of science, that science is not about proving things but about falsifying them.
Above we see that Dawkins, Stenger and company place their faith in the probability engineered by scientific facts. The problem is probability is not the basis upon which one chooses one theory over another, at least according to Popper. This insight forms the basis of this notion that science can give us verisimilitude not “facts.” Popper never uses the phrase “fortress of facts,” we could add that, science is not a fortress of facts. Science is not giving us “truth,” its’ giving something in place of truth, “verisimilitude.” The term verisimilar means “having the appearance of truth, or probable.” Or it can also mean “depicting realism” as in art or literature.” According to Popper in choosing between two theories one more probable than the other, if one is interested I the informative content of the theory, one should choose the less probable. This is paradoxical but the reason is that probability and informative content very inversely. The higher informative content of a theory is more predictive since the more information contained in a statement the greater the number of ways the statement will turn out to fail or be proved wrong. At that rate mystical experience should be the most scientific view point. If this dictum were applied to a choice between Stenger’s atheism and belief in God mystical God belief would be more predictive and have less likelihood of being wrong because it’s based upon not speaking much about what one experiences as truth. We will see latter that this is actually the case in terms of certain kinds of religious experiences. I am not really suggesting that the two can be compared. They are two different kinds of knowledge. Even though mystical experience per se can be falsified (which will be seen in subsequent chapters) belief in God over all can’t be. The real point is that arguing that God is less probable is not a scientifically valid approach.
Thus the statements which are of special interest to the scientist are those with a high informative content and (consequentially) a low probability, which nevertheless come close to the truth. Informative content, which is in inverse proportion to probability, is in direct proportion to testability. Consequently the severity of the test to which a theory can be subjected, and by means of which it is falsified or corroborated, is all-important.
Scientific criticism of theories must be piecemeal. We can’t question every aspect of a theory at once. For this reason one must accept a certain amount of background knowledge. We can’t have absolute certainty. Science is not about absolute certainty, thus rather than speak of “truth” we speak of “verisimilitude.” No single observation can be taken to falsify a theory. There is always the possibility that the observation is mistaken, or that the assumed background knowledge is faulty. Uneasy with speaking of “true” theories or ideas, or that a corroborated theory is “true,” Popper asserted that a falsified theory is known to be false. He was impressed by Tarski’s 1963 reformulation of the corresponded theory of truth. That is when Popper reformulated his way of speaking to frame the concept of “truth-likeness” or “verisimilitude,” according to Thronton. I wont go into all the ramifications of verisimilitude, but Popper has an extensive theory to cover the notion. Popper’s notions of verisimilitude were critixized by thinkers in the 70’s such as Miller, Tichy’(grave over the y) and Grunbaum (umlaut over the first u) brought out problems with the concept. In an attempt to repair the theory Popper backed off claims to being able to access the numerical levels of verisimilitude between two theories. The resolution of this problem has not diminished the admiration for Popper or his acceptance in the world of philosophy of science. Nor is the solution settled in the direction of acceptance for the fortress of facts. Science is not closer to the fact making business just because there are problems with verisimilitude.
Science doesn’t prove but Falsifies
The aspect of Popper’s theory for which he is best known is probably the idea of falsification. In 1959 He published the Logic of Scientific Discovery in which he rigorously and painstakingly demonstrated why science can’t prove but can only disprove, or falsify. Popper begins by observing that science uses inductive methods and thus is thought to be marked and defined by this approach. By the use of the inductive approach science moves from “particular statements,” such as the result of an experiment, to universal statements such as an hypothesis or theories. Yet, Popper observes, the fallacy of this kind of reasoning has always been known. Regardless of how many times we observe white swans “this does not justify the conclusion that all swans are white.” He points out this is the problem of universal statements, which can’t be grounded in experience because experience is not universal, at least not human experience. One might observe this is also a problem of empirical observation. Some argue that we can know universal statements to be true by experience; this is only true if the experiences are universal as well. Such experience can only be a singular statement. This puts it in the same category with the original problem so it can’t do any better. The only way to resolve the problem of induction, Popper argues, is to establish a principle of induction. Such a principle would be a statement by which we could put inductive inferences into logically acceptable form. He tells us that upholders of the need for such a principle would say that without science can’t provide truth or falsehood of its theories.
The principle can’t be a purely logical statement such as tautology or a prori reasoning, if it could there would be no problem of induction. This means it must be a synthetic statement, empirically derived. Then he asked “how can we justify statement on rational grounds?”  After all he’s just demonstrated that an empirical statement can’t be the basis of a universal principle. Then to conclude that there must be a universal principle of logic that justifies induction knowing that it ahs to be an empirical statement, just opens up the problem again. He points out that Reichenbach would point that such the principle of induction is accepted by all of science. Against Reinchenback he sties Hume. Popper glosses over Kant’s attempt at a prori justification of syetnic a priori statements. In the end Popper disparages finding a solution and determines that induction is not the hallmark of science. Popper argues that truth alludes science since it’s only real ability is to produce probability. Probability and not truth is what science can produce. “…but scientific statements can only attain continuous degrees of probability whose unattainable upper and lower limits are truth and falsity’.” He goes on to argue against probability as a measure of inductive logic. Then he’s going to argue for an approach he calls “deductive method of testing.. In this case he argues that an hypothesis can only be empirically tested and only after it has been advanced. 
What has been established so far is enough to destroy the fortress of facts of idea. The defeat of a principle of induction as a means of understanding truth is primary defeat for the idea that science is going about establishing a big pile of facts. What all of this is driving at of course is the idea that science is not so much the process of fact discovery as it is the process of elimination of bad idea taken as fact. Science doesn’t prove facts it disproves hypotheses.. Falsifying theories is the real business of science. It’s the comparison to theory in terms of what is left after falsification has been done that makes for a seeming ‘truth-likeness,’ or verisimilitude. Falsification is a branch of what Popper calls “Demarcation.” This issue refers to the domain or the territory of the scientists work. Induction does not mark out the proper demarcation. The criticism he is answering in discussing demarcation is that removing induction removes for science it’s most important distinction from metaphysical speculation. He states that this is precisely his reason for rejecting induction because “it does not provide a suitable distinguishing mark of the empirical non metaphysical character of a theoretical system,” this is what he calls “demarcation.”
Popper writes with reference to positivistic philosophers as the sort of umpires of scientific mythology. He was a philosopher and the project of the positivists was to “clear away the clutter” (in the words of A.J. Ayer) for science so it could get on with it’s work. Positivistic philosophers were the janitors of science. Positivists had developed the credo that “meaningful statements” (statements of empirical science) must be statements that are “fully decided.” That is to say, they had to be both falsifiable and verifiable. The requirement for verifiable is really a requirement similar to the notion of proving facts, or truth. Verifiability is not the same thing as facticiy or proof it’s easy to see how psychologically it reinforces th sense that science is about proving things. He quotes several positivists in reinforcing this idea: Thus Schlick says: “. . . a genuine statement must be capable of conclusive verification” Waismann says, “If there is no possible way to determine whether a statement is true then that statement has no meaning whatsoever. For the meaning of a statement is the method of its verification.” Yet Popper disagrees with them. He writes that there is no such thing as induction. He discusses particular statements which are verified by experience just opens up the same issues he launched in the beginning one cannot derive universal statements from experience. “Therefore, theories are never theories are never empirically verifiable. He argues that the only way to deal with the demarcation problem is to admit statements that are not empirically verified.
But I shall certainly admit a system as empirical or scientific only if it
is capable of being tested by experience. These considerations suggest
that not the verifiability but the falsifiability of a system is to be taken as a
criterion of demarcation. In other words: I shall not require of a
Scientific system that it shall be capable of being singled out, once and
for all, in a positive sense; but I shall require that its logical form shall
be such that it can be singled out, by means of empirical tests, in a
negative sense: it must be possible for an empirical scientific system to be refuted by experience.
What this means in relation to the “fortress of facts” idea is that it transgresses upon the domain of science. Compiling a fortress of facts is beyond the scope of science and also denudes science of it’s domain.
He deals with the objection that science is supposed to give us positive knowledge and to reduce it to a system of falsification only negates its major purpose. He deals with this by saying this criticism carries little weight since the amount of positive information is greater the more likely it is to clash. The reason being laws of nature get more done the more they act as a limit on possibility, in other words, he puts it, “not for nothing do we call the laws of nature laws. They more they prohibit the more they say.”
 Steven Thornton, “Karl Popper,” The Stanford Encyclopedia of Philosophy. Winter 2011 edition Edward N. Zalta Editor, URL: http://plato.stanford.edu/archives/win2011/entries/popper/ vested 2/6/2012
 Miriam-Webster. M-W.com On line version of Webster’s dictionary. URL: http://www.merriam-webster.com/dictionary/verisimilar?show=0&t=1328626983 visited 2/7/2012
 Thornton, ibid.
 Karl Popper, The Logic of Scientific Discovery. London, New York:Routledge Classics, original English publication 1959 by Hutchison and co. by Routldege 1992. On line copy URL: http://www.cosmopolitanuniversity.ac/library/LogicofScientificDiscoveryPopper1959.pdf digital copy by Cosmo oedu visited 2/6/2012, p4
 ibid, 5
 Hans Reinchenbach (1891-1953) German philosopher, attended Einstein’s lectures and contributed to work on Quantum Mechanics. He fled Germany to escape Hitler wound up teaching at UCLA.
 Popper, ibid, referece to , H. Reichenbach, Erkenntnis 1, 1930, p. 186 (cf. also pp. 64 f.). Cf. the penultimate paragraph of Russell’s chapter xii, on Hume, in his History of Western Philosophy, 1946,
 ibid, Popper, 5
 ibid, 6
 ibid 6
 ibid, 7
 ibid 11
 ibid, 17, references to Schlick, Naturwissenschaften 19, 1931, p. 150. and Waismann, Erkenntnis 1, 1903, p. 229.
 Ibid 18
 ibid, 19 the quotation about laws is found on p 19 but the over all argument is developed over sections 31-46 spanning pages 95-133.