“There can be no doubt that the knowledge of logic is of considerable practical importance for everyone who desires to think and infer correctly.”

President Niinistö commented the European refugee crisis while delivering an address to the Parliament of Finland on 3 February 2016.
Source: Tasavallan presidentti Sauli Niinistön puhe valtiopäivien avajaisissa 3.2.2016 http://www.presidentti.fi/public/default.aspx?contentid=341374&nodeid=44810&contentlan=1&culture=fi Website of the President of Finland. Retrieved 13 July 2017.

On Practice (1937)

The Ethics of Belief (1877), The Duty of Inquiry
Context: Belief, that sacred faculty which prompts the decisions of our will, and knits into harmonious working all the compacted energies of our being, is ours not for ourselves but for humanity. It is rightly used on truths which have been established by long experience and waiting toil, and which have stood in the fierce light of free and fearless questioning. Then it helps to bind men together, and to strengthen and direct their common action. It is desecrated when given to unproved and unquestioned statements, for the solace and private pleasure of the believer; to add a tinsel splendour to the plain straight road of our life and display a bright mirage beyond it; or even to drown the common sorrows of our kind by a self-deception which allows them not only to cast down, but also to degrade us. Whoso would deserve well of his fellows in this matter will guard the purity of his beliefs with a very fanaticism of jealous care, lest at any time it should rest on an unworthy object, and catch a stain which can never be wiped away.
It is not only the leader of men, statesmen, philosopher, or poet, that owes this bounden duty to mankind. Every rustic who delivers in the village alehouse his slow, infrequent sentences, may help to kill or keep alive the fatal superstitions which clog his race. Every hard-worked wife of an artisan may transmit to her children beliefs which shall knit society together, or rend it in pieces. No simplicity of mind, no obscurity of station, can escape the universal duty of questioning all that we believe.
It is true that this duty is a hard one, and the doubt which comes out of it is often a very bitter thing. It leaves us bare and powerless where we thought that we were safe and strong. To know all about anything is to know how to deal with it under all circumstances. We feel much happier and more secure when we think we know precisely what to do, no matter what happens, than when we have lost our way and do not know where to turn. And if we have supposed ourselves to know all about anything, and to be capable of doing what is fit in regard to it, we naturally do not like to find that we are really ignorant and powerless, that we have to begin again at the beginning, and try to learn what the thing is and how it is to be dealt with — if indeed anything can be learnt about it. It is the sense of power attached to a sense of knowledge that makes men desirous of believing, and afraid of doubting.

Source: A System of Logic (1843), p. 11: Cited in Gaines (1976) "Foundations of fuzzy reasoning" in: International Journal of Man-Machine Studies 8(6), p. 623

Speech (9 November 1978), as quoted in The Most Truthful Individual in Recent History" in Iranshenasi, Vol. XIV, No. 4 (Winter 2003), as translated by Farhad Mafie
Foreign policy

Quoted in Hawes The Logic of Contemporary English Realism (1923), p. 110;Most people would die sooner than think – in fact they do so. cf. Ockham's maxim: entia non sunt multiplicanda praeter necessitatem.
1920s

In the news

David Sayre, while in a panel discussion with Hopper, as quoted in Management and the Computer of the Future (1962) by Sloan School of Management, p. 277
Misattributed

Lecture I : Pragmatism : The Normative Sciences, CP 5.14
Pragmatism and Pragmaticism (1903)
Context: A certain maxim of Logic which I have called Pragmatism has recommended itself to me for diverse reasons and on sundry considerations. Having taken it as my guide for most of my thought, I find that as the years of my knowledge of it lengthen, my sense of the importance of it presses upon me more and more. If it is only true, it is certainly a wonderfully efficient instrument. It is not to philosophy only that it is applicable. I have found it of signal service in every branch of science that I have studied. My want of skill in practical affairs does not prevent me from perceiving the advantage of being well imbued with pragmatism in the conduct of life.