This is a fair sentiment, though I think it would be more accurate to say that no one knows all the facts,
some of it is speculation. There is a degree of unknown to this issue, as with most issues. But I believe it to be a bit of a reach to say that this is all blind guesswork.
That would be true at the most primitive level of common sense. Common sense would dictate that if there's a lot of traffic on I-275, then adding 2 lanes in each direction will lighten traffic flow.
That has now been proven to be false....adding two lanes simply results in more cars choosing to drive on I-275, with no improvement in congestion.
Common sense would dictate that if you owned a coffee shop and Starbucks opened up next door to you, your business levels would go down because you now face new competition. I'm sure at some point that becomes true, but both anecdotal and scientific evidence indicates that the "common sense" actually contradicts the reality.
"Why Starbucks actually helps mom and pop coffeehouses," Slate.com [[December, 2007)
Snyder's party is heavily influenced by a constituency whose anger about the current economic state overshadows in-depth policy analysis and sometimes even rational discussion.
In considering both sides of this debate, the credibility of arguments drops significantly as emotions rise. As the emotional intensity of advocates on either side reaches a feverish pitch, the less concerned about facts they seem to be...which is a recipe for short-term thinking and abysmal decision-making.
You're right that there is uncertainty with this question. It is inaccurate to state there are no certainties at all. And after eliminating the bluster and fury on either side of the argument...and then adjusting for conflicts of interest...it becomes fairly clear that those opposed to the bridge are doing so either out of self-interest or out of ideological fury.
As one distances themself from the actual people and political arguments involved, and as you speak with thinkers outside of the State of Michigan, the prevailing opinion is that we need a new bridge. The questions is simply, "Where?"
And since Canada has already outright excluded Moroun's proposed span repeatedly, the answer is almost self-evident.