Shaykh Hamza Yusuf has a short and valuable blog post entitled “The Lunacy of Lunar Sightings” in which he defends a middle position between naked-eye sightings and the use of astronomical calculations to determine the beginning and end of Islamic months. He argues for the need to establish Islamic dates based on a combination of the best-available scientific evidence along with naked-eye observation. I still think, however, it does not make the case for continuing with naked-eye observation rather than simply using calculations to determine the beginning and end of Islamic lunar months. Here, the decisive question is whether what is required is certainty or probability. The very fact that in traditional fiqh, the beginning and end of months could be established by the testimony of individual witnesses, and not the kind of corroborated testimony that Shaykh Hamza seems to demand in this essay, shows that certainty is not required in this matter. And, when this is combined with the element of practicality — something Shaykh Hamza dismisses too easily, I believe — it seems that simply using astronomical calculations, regardless of the fact of the naked-eye observation, makes sense. As far as an official public calendar, sure, that does require certainty, and perhaps there should be a specialized astronomical institute that can maintain an “official” Islamic calendar, but as Shaykh Hamza knows, one of the great disputes in fiqh on this matter is the debate between ikhtlilaf al-matali` and ittihad al-matali’, basically, whether the lunar calendar is the same in all places of the world, or differs according to one’s location on the planet. I believe that, if the standard is naked-eye observation, we must adopt the principle of ikhtilaf al-matali’, which renders the possibility of a unified Islamic calendar impossible. But in any case, at least for Muslims in the west, none of this is really relevant because we don’t use the hijri calendar for administrative purposes, only for religious ones, and from that perspective, having a sound basis to believe that the month has started or ended is sufficient. (There is also another fundamental point of disagreement with respect to how to interpret the Prophetic hadith on this topic: did the Prophet (S) tell his companions either to observe the moon or to count the days because that was a ritual command, or because that was the means that was easily available to his people to calculate the month? Shaykh Hamza’s position is that the means the Prophet (S) communicated to his companions were themselves a part of the ritual. There is certainly support for that position from the tradition, but why should we reject what seems to me an equally plausible view that it was simply the most convenient means available for them to calculate the month? After all, the Prophet (S) did not tell his companions to fast based upon the government’s declaration that the month has begun, nor did he tell them to cease fasting based upon the government’s declaration that the month has ended, but the jurists all concluded that a judge, based on competent testimony, can declare the beginning and ends of months. It seems bizarre to then say that we can’t use astronomical calculations to determine the beginning and ends of months because they do not correspond perfectly with naked-eye observation.