An account and a truly humanitarian defence of this position [“The separation between the history of a science, its philosophy and the science itself dissolves into thin air and so does the separation between science and non-science”] can be found in J.S. Mill’s On Liberty. Popper’s philosophy, which some people would like to lay on us as the one and only humanitarian rationalism in existence today, is but a pale reflection of Mill. It is specialized, formalistic and elitist, and devoid of the concern for individual happiness that is such a characteristic feature of Mill. We can understand its peculiarities when we consider (a) the background oflogical positivism, which plays an important role in the Logic of Scientific Discovery, (b) the unrelenting puritanism of its author (and of most of his followers), and when we remember the influence of Harriet Taylor on Mill’s life and on his philosophy. There is no Harriet Taylor in Popper’s life. 
Repudiate bullshit wherever you find it. Reason is worth standing up for.
But be smart about it. Instead of telling people they’re espousing nonsense, ask why they believe what they believe. Then really listen. Be genuinely open to changing your mind. Ask thoughtful questions. Examine the reasoning process that led to their conclusions. Keep your cool. Probe. Then hone in and expose instances of unreason.
What we want to do is create a culture where we take responsibility for what we say, what we think, and what we do. Education isn’t just about you, it’s about the environment around you.
Die Idee der kritischen Prüfung ist eine methodische Idee, die darauf zurückgeht, daß unser Denken und Handeln der Irrtumsmöglichkeit unterworfen ist, so daß derjenige, der ein echtes Interesse an der Wahrheit hat, daran interessiert sein muß, die Schwächen und Schwierigkeiten seiner Denkresultate und Problemlösungen kennenzulernen, Gegenargumente zu hören und seine Ideen mit Alternativen konfrontiert zu sehen, um sie vergleichen, modifizieren und revidieren zu können. Nur Anschauungen, die kritischen Argumenten ausgesetzt werden, können sich bewähren. Nur auf dem Hintergrund alternativer Auffassungen lassen sich die Vorzüge und Nachteile bestimmter Konzeptionen beurteilen. Es lohnt sich daher immer, ernsthaft zur Diskussion stehende Ideen in eine Form zu bringen, die solche Vergleiche ermöglicht und ihre Prüfung erleichtert und sie dann tatsächlich mit Alternativen und Argumenten zu konfrontieren. Nur in diesem Fall haben sie Gelegenheit zu zeigen, was sie für die Weltorientierung leisten.
The aim in an open society is not to put up with ideas with which we disagree. It is to take them seriously and to criticize them—not necessarily as a way of condemning them, but as a way of trying to understand them, and of testing whether or not they are true, and learning from them, even if learning from them means learning how and where they go wrong.
This is what Popper meant when he said that open society is ‘based on the idea of not merely tolerating dissenting opinions but respecting them.’ Open society is based on respect for other people, for their freedom and autonomy as rational agents—or, as Kant would have put it, for people as ends in themselves. It is not that we regard their ideas as evils that we have to tolerate for civility’s sake. And it is not even that we regard them as the ideas of other people who have just as much right to ideas as ourselves. That, at best, would be paternalism. And it would have nothing at all to do with a recognition of our own fallibility. Respect, on the contrary, means that we take the dissenting opinions of others seriously, and that we regard them as possibly true. It means, in fact, that we treat them as potentially our own—since we want to discover the truth and since we recognize that we may be in error—and it means, for this reason, that we try to do everything in our power to criticize them and to show that they are false.