according to the Mesilat Yesharim the way to have clear moral view is to be free of sin and this comes through torah study. otherwise one is trapped by rationalizations induced by desire. some sources
ch.5 So too in our case, for no one recognizes the illness of the evil
inclination and its powers except for the Creator who created it. And
He Himself cautioned us that the only remedy for it is Torah. Who then
will abandon it, take something else instead and expect to live?
Certainly the darkness of the physical will advance and strengthen
over him level after level, without his realizing it until he finds
himself sunk in evil, so distantly far from the truth that even
thoughts of seeking the truth will not enter his mind .
ch.10 But the man who was completely purified from this affliction and
has been cleansed of all trace of evil which lust leaves behind it,
behold his vision will be perfectly clear and his discernment will be
pure. He will not be swayed by any desire. He will recognize anything
which is a sin. Even for the most minuscule, he will see its evil and
will distance from it. On this our Sages referred regarding the men of
Sheleimut (Wholeness) who purified their deeds to such a great extent
as to leave not even a stirring of evil - "the clean minded men of
Jerusalem" (Sanhedrin 23a).
see also Rabbi Elchonon Wasserman paper on Daas Torah
...In simple people it is mixed with all types of influences and ideas
from the street, or the like. And according to how great the mixture
is, so too will be the diminishing of the percentage of "daas torah" .
Therefore a man who is fit to be a reliable advisor is obligated to
prepare in his heart "daas torah", 100% clean, with no trace of
mixture of other daas whatsoever...
and chovos halevavos gate 5 ch.5
be careful to not rely on your intellect nor to take counsel only with
yourself. Do not reason on your own. Do not distrust your forefathers
in the tradition they bequeathed to you as to what is good for you. Do
not reject their advice in what they taught you because none of the
plans you can think of were not previously known and their good and
evil consequences were already weighed.
UPDATE:some invoke the gemora of Eruvin 100b where Rabbi Yochanan says if the torah had not been given we would have learned modesty from the cat, chastity from the dove, etc.
but these inferences are based on the premises that there exists a God who created the world and He did so for man, hence we can learn to draw lessons from how He did it. but obviously without such knowledge (which comes from torah) one will not only not draw the lessons from the cat, on the contrary he will come to say the cat and even the human mind is merely a result of random mutations.