The phrase beside the point refers to something that's irrelevant to the main topic. It can be used in a positive way to steer a discussion toward a more pertinent direction. In a more aggressive setting, the phrase may be applied to a person to make him or his beliefs appear insubstantial or unimportant.
This phrase can serve as a form of comparison between two items, topics, and arguments. One is the subject of the comparison; the second is the item that is similar but not as relevant as the first. The characteristic being compared is relevance.
Michael Caine is quoted as saying, "I'll always be there because I'm a skilled professional actor. Whether or not I've any talent is beside the point." His statement illustrates a sophisticated use of this figure of speech. Here the comparison is between the relevance of talent to his success compared to the relevance of discipline and work ethic.
To be beside the point, the item must just miss the subject. As a successful actor, it would seem obvious that Caine must have acting talent. Yet, Caine argues that his continued acting work is due not to talent but to discipline and training. The proposition that he has talent is not under question. Talent is seen as irrelevant when compared to his work ethic.
An incorrect use of the subtle meaning of the idiom, as Caine employed it, would be to comment on something that was completely irrelevant. An example of this is given in the context of discussing the merits of broccoli: The calories burned while bicycling are surprisingly low is beside the point. In this case, the calories burned while bicycling are off-topic. The idiom implies a close degree of similarity that this example does not illustrate.
When one person is debating another, to note that the other person’s argument is beside the point is often taken as a negative. The statement may be quite true and even not offensive when expressed differently. In general, the remark "Let’s get back on track" is often construed more positively than "Your argument is beside the point."
Another variation of this phrase is to note that some position taken by the speaker is pointless. To be on point, on the other hand, is to be pertinent. A point well taken is a substantiated claim.