I want to discuss the Toulmin method briefly here, as ever since I first encountered it (as an undergraduate), I have found it pretty technical and somewhat perplexing. While I understand that it can be useful to break arguments down into technical terms, I also feel this method erases some of the naturalness that can come from framing an argument in a social context. Claims seem simple enough (until they become complicated by other variables). The warrant and the backing can get tricky. From what I gather, the warrant is what would make the data valid.
For example, if I say that Bob is a graduate student, the data supporting this could be his enrollment in graduate courses, and the reason why that data would be valid (the warrant) is enrollment in graduate courses generally means that someone would be a graduate student. If I were to scrutinize that warrant, it could be that perhaps an undergraduate could be enrolled in a graduate course (which was occasionally the case at my previous college). Then I might change the data to, instead of being enrollment in graduate courses, to Bob having been accepted into a graduate program and consequently being enrolled in graduate courses. Even then it could get tricky, as there tend to be outliers that somehow could make a general claim invalid. Words like "always", "never", "without fail" can increase the odds that a claim will be invalidated by something.
I find it easier to use "common sense" than to get hung up on warrants and backing, and to think about how most valid claims can be thought of as generally true, in most scenarios. True, there might be an outlier, but it's safe to say that A or B is often the case, with some exceptions. Thinking about what is "generally true" in a social context can be helpful. As in, "Eating fresh fruits and vegetables is generally healthy." The data: they contain vitamins, minerals, and little processed or no processed food.
Could it be argued that maybe eating fruits and vegetables is not healthy in all cases? A discussion on pesticides, allergies, and excessive consumption of fruits and vegetables could complicate my claim. Still--it's generally healthy to eat fruits and vegetables, and in American culture, this is an important claim to make, as it's better to promote these foods than other options. Perelman and Olbrechts-Tyteca state, "All language is the language of a community, be this a community bound by biological ties, or by the practice of a common discipline or technique" (513). When I think about claims and warrants and backing existing in community, it becomes slightly more straightforward to think about what generally works as a claim than to get halted by considering all possible exceptions to the claim.