Answer
Salam Dear Brother,
Thank you for your question and for contacting Ask About Islam.
“In philosophy, rationalism is a theory that holds that reason alone, unaided by experience, can arrive at basic truth regarding the world. It is opposed to empiricism on the question of the source of knowledge and the techniques for verification of knowledge.”
Empiricists believe that we get knowledge of the world from experience gained through the five senses. In other words, rationalists say that we may find out the truth about the world by logical thinking, while empiricists claim that knowledge is obtained through constant observation.
Rationalism is also contrasted with the idea that faith and revelation too are valid sources of knowledge and verification.
If you use the methods of the above three doctrines – namely of rationalism, empiricism and faith (revelation) – to assess the validity of the same doctrines for all practical purposes, we can see that all of them have their place in life as lived by us every day.
The problem is when the adherents of each of these doctrines claim that only that particular doctrine is valid to the exclusion of all others.
In the march of human progress in all spheres of human endeavor such as science, technology, art and the efforts for peace-building and social cohesion among other things, we badly need reason, experience and faith.
In the laboratories of science, experiments are conducted, the processes as well as their results are observed and inferences are made. In such cases, both observation using the senses and logical reasoning are crucial.
In order to achieve social or national integration among disparate groups in the society or country for instance, we need to have faith not only in the goodness of our fellow beings, but also in the religious values of truth, justice and sympathy.
The rationalists adopt a one-sided view of the world: they ignore a good share of the profound complexities of the wealth of human life. Their approach is effectively reductive, as they cast doubt on knowledge that is not derived by logical thinking.
The website you mentioned, namely lesswrong.com is typical of the rationalists. If you read the articles posted on the site, you can see how they push their rationalist methods even beyond the limits of reason.
From the Islamic point of view, one may say that their over dependence on rationality amounts to a sort of self-sufficiency and arrogance which smacks of nothing less than the Satanic, as Satan or Iblis is the epitome of arrogance.
Islam teaches that Reality has two dimensions – one is accessible to human perception (called the shahadah); and the other is inaccessible to human perception (called the ghayb).
We may arrive at knowledge of the shahadah or of the perceptible world using reason and observation. But only a small fraction of the knowledge of the ghayb or the imperceptible world, we can hope to attain.
This we get from the scriptures revealed by God to His prophets. From this point of view, revelation is a valid source of knowledge, as regards Reality beyond the confines of the physical world accessible to human observation and rationality.
The foregoing means human knowledge is the sum total of what we gain through the God-given channels of the five senses and our reasoning faculties, as well as through Divine Revelation.
Allah Almighty says in the Quran:
{Behold! in the creation of the heavens and the earth; in the alternation of the night and the day; in the sailing of the ships through the ocean for the profit of mankind; in the rain which Allah Sends down from the skies, and the life which He gives therewith to an earth that is dead; in the beasts of all kinds that He scatters through the earth; in the change of the winds, and the clouds which they Trail like their slaves between the sky and the earth;- (Here) indeed are Signs for a people that are wise.} (Quran 2:164)
The above verse, among others, inspires the readers of the Quran to observe and study the phenomena of nature, which indeed are the signs of the Creator. That is to say, rather than blind faith, it is an informed faith buttressed by empirical evidence and reasoning that He urges us to have.
Most assuredly, faith in God serves as the greatest incentive to lead a good life in this world. For, God is not only the Source of all good, but also the Judge and Arbiter of all our deeds. As the servants of Allah Almighty, our duty is to wholeheartedly submit to Him and earnestly strive and pray for His mercy and blessings.
And Allah knows best. I hope this helps answer your question.
Salam and please keep in touch.