Is the month of Ramadan established by visual sighting or by astronomical calculation? And is it permissible to establish Islamic rulings based on scientific theories?

I would like to draw attention to a very important aspect that many jurists, especially contemporary ones, often fail to notice. I intended to complete my discussion, but then a thought occurred to our brother, Professor Abu Malik, and as you saw, he asked my permission to share it. It was, in fact, a confirmation of exactly what I wanted to say, or at least it reminded me that I had begun with two examples of matters where science makes a judgment, but the Shari'ah does not agree with one of them at all, which is a matter of consensus, and for the other, I said there is disagreement among Muslim scholars. Then I began to mention this example: the issue of establishing the crescent moon by astronomical calculations. Here, Professor Abu Malik intervened and mentioned what you all heard, namely that there is a scientific dawn and a Shari'ah dawn, and that this discussion took place between an astronomer and an employee at the Waqf (Endowment) office. This example became, in my calculation and previous mental arrangement—which I had distorted and intended to present—our third example. I mentioned the first example to you, which is establishing the Ramadan crescent by astronomical calculations or by optical observations. Undoubtedly, I personally do not prefer the opinion of some scholars who establish the crescent by this scientific observation, due to the well-known saying of the Prophet (peace and blessings be upon him) in the two Sahihs: meaning that the month may be thirty days or twenty-nine. Therefore, I do not see the establishment of the crescent except by visual sighting, because the Messenger (peace and blessings be upon him) explicitly stated this in this specific ruling. Then I say: if the door were opened to establishing Islamic rulings based on scientific theories, the Islamic Shari'ah would suffer what the previous laws of Judaism and Christianity suffered. Now comes the second example in my distorted thinking, and the third spoken by our companion Abu Malik. Science says—and an objector might oppose me because I am not a specialist, but in my opinion, there is no valid objection—when we see the sun like this, toward the west, rising above the peak of a mountain, meaning a very large circle, science says the sun is now behind the horizon. What we see is due to a scientific principle we do not understand: the rays reflect and refract to us, so we see the sun above the mountain peak, while in reality it is behind the mountain. Now, the Prophet (peace and blessings be upon him) says: . A man among the people delays the Fajr prayer until he sees the sun above the mountain peak with his eyes, but by his own knowledge, he knows it is behind the horizon. Is it permissible for him to pray or not? If we apply the Shari'ah ruling linked to personal vision, he prays because the sun is still rising, but scientifically it is behind the horizon and not visible. And so, the sun rose above the mountain peak; scientifically it did not rise. Is it permissible to pray Fajr? The answer is: it is not permissible. Look at how Islamic rulings differ between building them on ordinary vision and building them on scientific thought. Therefore, we say that a Muslim should be consistent and straight, naturally, in the consistency of his thought, and not be confused, sometimes taking a scientific theory even if it contradicts the Shari'ah truth, and sometimes not taking it. If we understand these examples, the last of which was mentioned by Professor Abu Malik, that astronomy says the dawn and Fajr appear about a third of an hour before the dawn we see with our eyes. This exactly meets the theory I mentioned earlier when the sun is above the mountain peak; scientifically it has not risen, and likewise, Fajr has not risen scientifically, but theoretically, we see it with our own eyes.
The questioner: The false dawn...

The Shaykh : In any case, this is a technical term. The important thing is that we do not base our Islamic rulings on scientific theories, even if they become scientific facts. Why? Because if there is fog and clouds on the horizon...

The questioner : ...

The Shaykh : Yes. If there is fog and clouds on the horizon, and a person with strong vision cannot see the crescent, but a magnifying glass many times stronger is brought, the crescent will be discovered behind the clouds. This is a scientific fact without doubt, but we are not obligated to use this view. We are obligated by what we see with ordinary vision. Therefore, Islamic rulings are not built on scientific facts, but on ordinary, natural theories. So, it does not concern us that science has proven that the earth rotates and has the two known rotations. This does not concern us, because the rulings of the Shari'ah were built on the premise that the earth is flat like a surface, whereas in scientific reality, it rotates and is spherical. This does not harm us in our religion at all, because the Islamic rulings established by the Wise Lawgiver were established for ordinary people with limited visual and intellectual capacity, and they were obligated by that and not by more. If we understand this, this man whose heart is still beating—doctors have ruled that he is dead, but by ordinary human vision, he has not died. Therefore, they do not rush to bury him until they are certain of his death by their ordinary means. On this basis, I do not see it permissible to kill this person because, in the opinion of medicine, he is dead. We do not let him die until his heart cools and does not beat; I do not see this, because in the Shari'ah, he is still not dead. At the very least, this is the opinion I wanted to clarify for you, and we ask Allah, Mighty and Majestic, to inspire us with the truth in what we say and believe.

The questioner : I mean, Shaykh, after he dies, is it permissible to transplant an organ from him?

The Shaykh : I do not see this. This falls into another category: mutilation. I do not see this.

The questioner : Another question: the prohibition of mutilation?

The Shaykh : We do not have this scale that gives us the weight of a Muslim. What is your weight in the Shari'ah, and the weight of the benefit of the living person who needs a heart? He might die. We do not have these precise scales to be able to give an answer.

The questioner : So the answer is confusing in this matter, that we cannot give an answer.

The Shaykh : No, how? We cannot? You have a prohibition that you do not exceed for a circumstance that occurred to a person, which is transplanting this heart to a sick man.

The questioner: ...

The Shaykh : Okay, my lord, here you have the prohibition of mutilation. What opposes it? Is there another text? We do not have a second text.

The questioner : Necessities permit the prohibited.

The Shaykh : There is no necessity. Necessity is related to the obligated person.

The questioner : The person who needs the heart is exposed to death at any moment.

The Shaykh: Correct.

The questioner : And he needs to live.

The Shaykh : But I say that necessity does not relate to two people: one holding onto the Shari'ah text for his own sake, meaning that this person has died and it is not permissible to mutilate him, and another person saying the doctors say he needs this dead person's heart. He cannot exceed to take this heart because the necessity is not related to the dead person himself, but to another.

The questioner : Even if, Shaykh... The Prophet (peace and blessings be upon him) said: .
The Shaykh: What do we say, my brother?

The questioner : I mean, whether he is alive or dead.

The Shaykh: Yes.