There is a thumb-rule which states that any journal of philosophy that publishes contributions from graduates or lecturers in Film Studies or somesuch fluff is a journal unworthy of serious attention. The rule serves to remind us that, for the sake of precious time, one had better attend to more important matters — to weeding the garden, to cleaning the lavatory, to seeing how many mints one can balance on one’s tongue — than to reading such likely piffle. As with all thumb-rules, however, it has its failings; after all it is possible that a serious journal of philosophy will one day publish a contribution from a graduate or lecturer in the aforementioned studies that is worthy of serious attention, a contribution which we would miss if we were to cast the journal out of hand with a flick of the figurative thumb.
.....On a day in which I find myself at a loose end without mints and in the avoidance of work, I have persevered with the written work of one Nick Redfern, postgraduate in Film-Studies and proponent of the doctrine of Radical Constructivism, published in the soberly named journal Essays in Philosophy:
Radical Constructivism does not deny the existence of a reality independent of the mind of the historian, but states that, as the historian is limited by his or her experiences, such a reality cannot be known. 
.....Now, it does not follow that because a man is limited by his experiences, he cannot know a mind-independent reality, unless one defines experiences as those things which preclude knowledge of a mind-independent reality, in which case one begs the question. One might suggest — quite unradically — that not all experiences are limitations that keep one away from a mind-independent reality, but rather that at least some of them are informed by a mind-independent reality. It is after all a strange conception to view experience as a prison, in which the mind is locked away from all contact with the outside world, indeed so strange and counter-intuitive that one might expect to find a stronger argument to account for its acceptance. Yet one does not.
.....The argument brought forth by Mr Redfern is a variation of an old one that has found many forms throughout the ages, an argument that is at least as old as the bones of the Sophists. The modern forms of the argument are usually a little more sophisticated – or, at least, they usually take up more space on the page – but the argument is essentially the same: since one knows the world only in relation to oneself, one knows nothing of the world outside of oneself. But as already stated, the argument is either non-sequitous or question-begging. It would be more honest, therefore, if its proponents would drop it in favour of an open declaration of a besetting doubt. Mr Redfern is in no such mood, however:
The key to evaluating competing knowledge claims, therefore, is not to seek to compare them to a mind-independent reality that cannot be known, but to assess their cognitive viability or functional fitness. 
Thus, Newton’s contention that the gravitational field of a body is proportional to the body’s mass and varies inversely with the square of distance from the body is a claim that is best evaluated not by observation of a mind-independent reality, which, as any lecturer worth his weight in academic pap will tell you, cannot be observed, but rather by its “cognitive viability” or its “functional fitness”; or, in other words, we should evaluate all claims to knowledge only by how well they fit in with whatever we already believe.
.....One shouldn’t be surprised if it turns out that this man is a proponent of a radical politics that requires a radical constructivism for its defence, whereby he can continue to believe what he likes.
 Nick Redfern, “Realism, Radical Constructivism, and Film History” Essays in Philosophy: A Biannual Journal, Vol. 7:2, June 2006. Original emphasis.