Many mistake expressing opinions with thinking but then thinking is itself not free of opinion, i.e. one angle out of many on a certain issue.
Perhaps philosophy is just glorified opinion but more elaborately woven and hopefully more measured than reactive (and reactionary) prejudice.
It could also be said that philosophy is active opinion on matters of existential substance whereas a great deal of commonplace opinion merely reacts to statements and events that are transient and of little import as evidenced by the appalling television programme Question Time - whose questions aren't questions at all but loaded innuendos designed to provoke controversy and bitter reaction - and spiteful online comments to newspaper articles.
Which is why some recommend being well informed as opposed to being merely opinionated.
Yet information can only influence opinion, not be a substitute for it, which is why information control is said to be the greatest weapon of all, opinion leading to action.
Perhaps the operative difference between thinking and expressing opinions lies in the fact that thinking involves the critical evaluation of information and phenomenological data - critical evaluation being at the basis of authentic knowledge - whereas opinions can be readily reached without said evaluation and without the introspective labour on the self that philosophising requires.
And it is the case that some opinions are more in-formed than others, more in tune with that which is (truth) and less determined by the methodologies of mass mind control usefully covered by researcher Mark Passio and summarised in a previous blog post of mine (Mass Mind Control Techniques).
Moreover, my girlfriend sees thinking as being an ongoing journey of self and world exploration that is continually learning whereas opinions seek always to immediately conclude and have the final say on contentious points (see The More You Know the Less You Think You Know).
Perhaps it was the difference between the ongoing and open-ended nature of philosophical thinking and the closed-minded and desired finality of political opinion that French novelist Gustave Flaubert had in mind when he wrote
"C'est une bêtise que de toujours vouloir conclure"[It's a nonsense to always wish to conclude]
although Flaubert's statement too can be seen as wishing to conclude.
Nevertheless, it could be argued that to opine, in its desire for the finality of the final say, can potentially be seen as thinking against time, the cycle of becoming and ceaseless change that we belong to as human beings, whereas to think properly speaking, i.e. to philosophise, can be seen as thinking along and in harmony with said cycle of becoming, thereby requiring the making of one's peace with nature's transience, one's own past and philosophy's lack of finality (as much-loved philosopher Wittgenstein discovered later on in life having previously thought he had resolved all philosophical problems in his first book).
To make the leap from opinion to thought would imply, if the thoughts/opinions I have shared above are correct, a letting go of the desire to be final and forever resolved in conclusive gestures in favour of a learning dynamic of endless self-correction and self-amendment. For philosophers (from the Greek φιλόσοφος, composed of φίλος, friend, itself linked to φιλία, love, and σοφός, wise, derived from σοφία, wisdom) are mere lovers of wisdom which is to say they know, the good ones at least, that they do not possess it and never will, at least not completely.
Even German thinker Friedrich Nietzsche who made no qualms about his wisdom in his books, including his autobiography Ecce Homo (which contains a section entitled 'Why I Am So Wise'), considered, in his works Thus Spoke Zarathustra and Beyond Good and Evil, wisdom to be a woman who offered her favours only to warriors of the spiritual realm, i.e. to truth-seekers rather than to the truth-holders that are dogmatists of all stripes and sizes (Nietzsche claiming in Beyond Good and Evil that dogmatism was no longer tenable), such as many so-called scientists and political commentators today, that have policed thinking, what is acceptable discourse and what isn't, throughout the ages.
To conclude, despite what I have said about the matter, I will say that genuine philosophical thinking stems from a place of magnanimity whereas the immediate expression of opinion often but not always stems from a place of impatience. And if philosopher Martin Heidegger's words are true
"patience nurtures magnanimity"the converse also holds, i.e. magnanimity nurtures patience and the ability to refrain from opinionated commentary. For, according to Plato,
"wise men speak because they have something to say; fools because they have to say something."Addendum - It could be questioned whether the suggested definition of 'opinion' in this writing, 'one angle out of many on a given issue', does not apply more vigorously to the concept of 'point of view' or 'perspective'. This would raise the further question of whether one's point of view necessarily involves an angle or can even exist without an 'angle' or 'side', whatever that means (see in this respect My Side as Anti-Side which basically shows that not having an angle is itself having an angle).
Perhaps an opinion is simply a stated point of view on a given topic, which performative definition is implied in the expression 'holding (i.e. presenting and defending) an opinion'. An opinion would become a conviction when one is completely won over (i.e. defeated, con-viction being similar though not identical to the Latin victor, to defeat) and capitulates entirely to one's own (stated) angle, which is to say when one is no longer open to changing one's mind or (stated) point of view. Whence
"convictions are more dangerous enemies of truth that lies"(for more elaboration on this view see Truth: Six Aphorisms by Nietzsche)To the thoughtful person, yet more questions arise as to the exact distinction between opinion, assertion and claim. I would imagine that an assertion - a statement that lays claim to something - is not backed by any research or proof whereas a claim in the intellectual sense presupposes the existence of potential supporting evidence that needs to be looked at and considered. Forming an opinion requires neither real research nor evidence but, as an opinion, may have a more modest intent and purported scope than an actual assertion and certainly less prestige and (apparent) intellectual sophistication than a claim.