Until recently we consider the buying power of the dollar in the same way. But quantitative changes beyond certain limits become converted into qualitative. A pound of sugar subjected to the action of water or kerosene ceases to be a pound of sugar. A dollar in the embrace of a president ceases to be a dollar. To determine at the right moment the critical point where quantity changes into quality is one of the most important and difficult tasks in all the spheres of knowledge including sociology.
Every worker knows that it is impossible to make two completely equal objects.
By observing the norms of tolerance, the cones are considered as being equal. Our scientific thinking is only a part of our general practice including techniques. Common sense' is characterised by the fact that it systematically exceeds dialectical 'tolerance'. Morals are equal to morals, etc. Dialectical thinking analyses all things and phenomena in their continuous change, while determining in the material conditions of those changes that critical limit beyond which 'A' ceases to be 'A', a workers' state ceases to be a workers' state.