Brian Jones’s summary of Anti-Dühring (May–June 2008) neglected to say that with respect to philosophy, it is among the worst books ever written by a revolutionary.
Space prevents me from outlining its many errors, but one example will do: the “law of the transformation of quantity into quality.” While it is true that some things change “nodally” (in “leaps”), many do not. When heated, metal, glass, plastic, butter, toffee and chocolate melt smoothly. So, the “nodal” aspect of this law is defective. To be sure, some things change “qualitatively” (exactly as Engels says); once more, many do not. The order in which events take place can affect “quality.” For example, anyone who tries pouring a pint of water slowly into a gallon of concentrated sulfuric acid will face a long and painful stay in hospital, whereas the reverse action is perfectly safe. Worse still, this law is hopelessly vague. For instance, we have yet to be told the precise length of a “nodal point.” But, if no one knows, then anything from a geological age to an instantaneous quantum leap could be “nodal”! In addition, Engels failed to say what he meant by “quality.” Hegel understood this word in an Aristotelian sense. That is, it refers to a property, the change of which alters an object into something new. Unfortunately, given this “definition,” many of the examples dialecticians use to illustrate this law would fail. For example, the change from water to steam can’t be an example of “qualitative change”; ice, water and steam are all H2O. Quantitative addition or subtraction of energy does not result in a qualitative change of the required sort; nothing substantially new emerges.
Faced with this, we might try to widen the definition of “quality” to neutralize this objection. Alas, while this might rescue the above example, it would sink the theory. If we relax “quality” so that it applies to any qualitative difference, we would have to include the relational properties of bodies. In that case, we could easily have qualitative change with no extra matter or energy added. For instance, consider three animals in a row: a mouse, a pony, and an elephant. In relation to the mouse, the pony is big, but in relation to the elephant, it is small. Change in quality here, but no matter or energy has been added or subtracted. Plainly, that would make a mockery of this law.
Finally, consider stereoisomers: molecules with the same number of atoms arranged differently. Here we have a change in geometry producing a change in quality with the addition of no new matter or energy.
This law’s other serious weaknesses are detailed at my site: http://homepage.ntlworld.com/