I have mentioned in a previous post that arguments have four parts. One of these is the starting point. A starting point is the place to start an argument from and must be something that your opponent agrees with. Finding a starting point that your opponent will agree with is not a matter of following a formula. Neither does it have to be something that you agree with. However, in general there are three places to find starting places: majority opinion, common opinion and expert opinion. We should select a relevant, general opinion from these and argue from there.
All starting points are drawn from the three sources of common opinion, majority opinion and expert opinion. A common opinion is something that everyone believes and there is no debate at all by anyone. For example, it is commonly believed that tomatoes are edible, that cancer is a horrible disease and that murder is wrong. No one disagrees with these things. Now if an opinion is not drawn from these three sources, then it is unlikely that your opponent will agree with the starting point. It might be possible for your opponent to disagree with one of these – especially majority opinion or expert opinion. However likely that is, it is much more likely that they will disagree with something that does not belong to those three categories. It is for that reason – the need to have your opponent agree – that we must select starting points from those three categories.
Which opinion to select is a much more difficult issue. First, it should be a general opinion. It is much better to start from “harming people is wrong” than “harming people with knives is wrong”. While both are common opinions, the first one can be used in more arguments than the second. It is also good to focus on what really matters. Knives do not matter, but causing harm does matter. Second, the opinion has to be relevant to the answer you are giving to the problem. If the problem is “Is Coke better than Pepsi or not?”, the healthiness and taste of Coke and Pepsi matter, but their popularity does not matter. Better than is a claim about which one more closely approximates the perfect kind of pop, not which one we think approximates it or which one claims to approximate it. So we should use general truths about taste and healthiness as our starting points. For example, “healthy things cause fewer health problems than unhealthy things” and “Bitter things do not taste as good as sweet things”. This will not give us an argument, only a starting point. Without starting points, though, there is no argument at all.
With an awareness of what to look for in starting points, it becomes much easier to try and find an appropriate argument.