Newton's directly contradicts the equations of relativity and vice versa. The standard model does not accurately explain relativistic interactions and vice versa. They are all obviously not all true, or we would have a ToE. They are obviously each incorrect as they have direct contradictions to them in experimentation and data as well as large areas where they do or do not apply. Each has overwhelming evidence for it, and they all can't be true.
Actually, they can contradict each other and still be right, within certain parameters. Newtonian mechanics can be true when relativistic issues are of no concern, the Standard Model can be true at subatomic scales and GR can be true at macroscopic scales. None of these theories are considered to be a ToE but are very useful within their respective domains. Now String Theory (or M Theory as some call it) is a different story.
So Newton mechanics can be true within a falsehood? Thats perhaps useful, but it says nothing to the point or its actual validity.
The standard model and GR can both be true at macroscopic scales, perhaps, but they are not at present time.
String theory is the movement of science away from hard science and into pure zeteticism due to its constant hatred (from social and political concerns) of the philosophy that supposedly backs science.
Obviously they are useful in their domain. The clear point was that this is irrelevant as it is not the "truth" of the matter, but the truth up to our understanding. If any of these theories were true it is likely that we would have little need for science at all.