It is most feasible to buy David Hume's standpoint above, given that at most times, what appears to have been comprehended by human understanding is found many times to be subject to ignorance and obscurity. The veracity of this notion is well supported by the concept of appearance versus reality. In most cases, what appears to be factual is often found to be in contrast to reality. For instance, a person walking along a tarmac road in a hot sunny afternoon may be duped by mirage to think that the road's surface has water suffusing over it, while the reality is not case. To this effect, it is true that in order to establish the truth, it is expedient that the investigator is cautious first.
By being cautious, it is meant, the ability to doubt the facade and to question the appearance, while giving room to other probabilities. Being cautious in this case is important as it allows for skeptical scrutiny, a critical stage of investigation that is supported by Dr. Karl Segal. It is by being skeptical that the investigator can be said to be both independent and open minded in any field of investigation. The researcher or learner who is able to be open minded is the one who can best understand new constructs and fathom the mysteries of unknown phenomena since he has shed from himself, the shades and prisms of his acculturation and socialisation from off the eyes of his mind. For instance, a fledgeling anthropologist willing to study the importance of other cultures may have to put away his social atavistic attitude which had initially taught him that his ethno-linguistic heritage and way of life is the most superior. It is only at this juncture that the budding anthropologist will be able to appreciate the beauty of uniqueness that characterise any ethno-linguistic group's total way of life.
At the same time, it is only when an investigator is hesitant to admit to any prior hypothesis by disregarding mere manifestations of outward appearances that the value of objectivity can be instilled in any interdisciplinary forms of investigation. It is objectivity (as opposed to subjectivity) which will allow the investigator to overcome the temptations of succumbing to personal interests, emotions and aspirations. For instance, a Christian Theologian must never attempt to manipulate or discount archaeological evidence, merely on the account that he fears that the claim of his dogmas may be undercut. On the contrary, he must allow for conclusive investigations to be carried out, since true religion must be supported by both historical and non-historical facts.
In almost the same wavelength, it is upon the ability to doubt a hypothesis that is devoid of support by actual appearance of probability (concrete observable evidence) that empiricism in systematic and scientific research can be realised and consolidated. Given that empiricism asserts that in order for a notion to be passed on as true, the processes involved can be carried out by anyone to arrive at the conclusion of the truth must be standard and uniform; it cannot be gainsaid in any field of scientific research and investigations. For instance, because of empiricism, it is mandatory that anyone on adding two Hydrogen molecules to an Oxygen molecule, must find H2O which is water, provided the right procedures were followed by the investigator. Likewise, any budding linguist (or more specifically, phonetician or phonologist) can ascertain that velarisation as a phonological process will take place upon a phoneme preceding a velar phoneme like /k/.
As a summation to all the above, David Hume seems to say that it is important that one doubts (being independent and open minded) before taking any assertion as true. On the contrary, the establishment of the truthfulness of a claim should be premised on clearly observable and ascertainable evidence. Thus, Hume vouched for scientific approach to research and investigation. To discount Hume's standpoint is to open room for probabilities and working with and on probabilities. This could be dangerous to any civilisation since there is no congruence between facts and probabilities.