What is false cannot be true and what is true cannot be false, but every particular person has their opinion about things, opinions even absurd when examined. It is not that these opinions are unjustified or that the people holding them are stupid, far from it. You can see if one is to engage a person that for the most part their justifications for their ideas are largely sound even though we find it evident that their idea is false, for they also find it evident that what they believe is true. But how come? And what does that mean for truth? As truth as it is cannot be attributed to two categorically contradictory statements.
For this we must bring to mind the reality that a belief is not merely a neutral standpoint on a certain question but it also affects how people build their beliefs and, based on that, act in life and receive confirmations and feedback about those beliefs from the external world. So beliefs are not only mental equations that can be mathematically proven false and then nothing is affected but the idea falsified itself. In most cases, a change of opinion entails a whole change in perspective, for a belief does not stand by itself but is a node in a larger web of other beliefs. From a logical standpoint, a belief about a certain proposition will lead, if thought about, to another series of beliefs that will inform decisions, behaviors, self-perception and the model of the world each person has built in their mind. Whether one has done this with an open mind or closed-minded as colloquially expressed does not matter much because everyone that thinks and has beliefs has gone through this either consciously and willingly or otherwise. As social creatures we often even do this collectively, and this process of changing one’s mind is not only psychologically difficult or even impossible but I might even dare say rational as it cuts off cognitive costs.
But before continuing I must distinguish, though regrettably since even this can be contended with, I must distinguish between truth as it is, justified beliefs, and certainty. For truth is not simplifiable to mere justified beliefs, nor are justified beliefs always certain in the mind of the individual, and truth as it is is something we barely can touch on merely mentally. And why I think this distinction is important is that the holder of the belief can often confuse what feels certain with what is true, and what is justified with what is certain or with what is true. Now we cannot deny that there are cases where they can intersect, but often it is more nuanced than that, and in other cases they are mutually exclusive.
Now as for these categories I put out, I can attempt to explain to the best of my ability how, as I said, falsehoods become evident truths. For one, justified beliefs that are false can be evident to their holder based on the falsehood of the prior beliefs and assumptions that led to their derivations. Even true evident beliefs and assumptions can lead to false views given the factor of misinterpretation, for a statement of any sort can be understood in many ways and in some instances ways that are contrary to the intended or correct idea. And as for certainty about beliefs, it engenders a peculiar effect of leading the one who is certain to a focalized perception that only sees what confirms its certainty and at times to levels of narrow vision that makes one unable to consider different viewpoints or perspectives.
Let me be clear, I am not suggesting that Truth does not exist or is elusive or that its nature is subjective as that view of subjectivism and epistemic nihilism has a whole host of problems that render it untenable but I am highlighting the fallibility of our own reasoning faculties and how we can fall into pits of false beliefs and are hence unable to see and discern our beliefs from what is correct, and with that let us continue, then if one is willing to examine what he is certain about and what he believes and is justified for believing and is willing to come closer to what is true, what errors does he need to avoid committing? What aspects of thought lead to falsehoods ? There are many and we commit them far more than we do not, as we might commit mistakes in logic or even not use logic at all, we might draw logical connections that are fallacious and we might start from false starting points. or commit ourselves in thought with our own flawed interpretative framework. All these can stray us away from truth closer to falsehoods and we would do better to avoid these if our priority is to attain knowledge of things as they are which is the essence of philosophy, but I would say that it is not always of benefit to most who have their hearts not in love for truth but for getting by in existence as often emotional committment to false beliefs can be painful and can be destructive to sever completely.