I have often been asked to explain the various opinions regarding shaving with an electric shaver. Without addressing any of the Kabbalistic aspects, as they are above my pay grade, I would like to elaborate on the basic Halachic positions of those who are stringent and lenient.
The Mishna in Makkos on Daf 20a writes that one only receives lashes for transgressing the prohibition against shaving when a razor is utilized. The Pesukim (Vayikra 21:5 and 19:27) describe the Issur as both “shaving” the beard as well as “destroying” the hairs. The Gemara on 21a elaborates that a scissors is not included in “destruction” though it would qualify as “shaving”. On the other hand, the Gemara continues that tweezing the hairs would be excluded because it is not considered “shaving”, even though the hairs are destroyed from the roots.
From this Gemara the Poskim derive that to be forbidden, two qualifications must be met. To be considered “shaving” a method considered a typical procedure for cutting the hairs must be employed. An electric shaver would certainly meet this requirement.
However, there are two basic opinions regarding the definition of “destroying”. The more stringent position considers anything that leaves no perceptible stubble to have removed all hair above the skin level equivalent to a razor, and considers this included in the Biblical prohibition against shaving the face. Consequently, most high-end electric shavers would be problematic. The important factor is the results, and in this they are identical. (This point itself is debatable. It is very questionable if any electric shaver can cut quite as close as razor due to the intervening shield.)
The second view distinguishes between a tweezers which uproots the roots from within the follicle and is certainly “destruction” with a method of cutting. In their opinion, any blade that does not cut independently and requires an opposing surface to create a scissor action is inherently different than a razor. Furthermore, according to this opinion, if the blade does not make direct contact with the skin, it is intrinsically different than a razor and is more similar to a permitted scissor. Since all electric shavers consist of a screen or grill between the blade and skin, they would be permitted.
The majority of Litvish Poskim in Chutz l’Aretz, including apparently Reb Moshe Feinstein zatzal although there is no explicit Teshuva from him on this subject, followed the second more lenient view. However, the Chassidic and many Sefardi Poskim ruled stringently, in addition to giving greater weight to the Kabbalistic concerns. Additionally, a number of the Litvishe Poskim in Eretz Yisroel subscribe to the more stringent position. Other authorities cite additional issues such as whether shaving is inherently “not Jewish” or gives a feminine appearance. Ultimately, each individual should follow his Rav and Posek.