Machines use other machines in their construction.Regarding machines adding value - machines are the product of human labour.
The mere fact they increase the efficiency of production means value added. The overall increase in productivity comparing the presence of machinery or other tools to the absence of it is, in fact, the definition of adding value. Then of course there is the fact that mobilizing the resources necessary for the acquisition of said machinery is itself value-adding. It requires acquiring large amounts of investment capital, which few people can by themselves fund (very few factory outfits today are sole proprietorships and those that are are leveraged to the hilt -- capital machinery is very expensive), which is why capital exists in the first place. In socialist countries the norm is for the state to take over that role (something I'm not necessarily opposed to, mind).Captial is "dead human labour" in Marx's words. They increase the efficiency of production, but do not add value above that which was paid for them
Zero-sum fallacy. Capitalist economies grow because their overall output grows -- ergo it's possible for continuous transactions to yield continuously rising profits if it were otherwise, the outcome would be either 1) stagnation of both profits and wages, or 2) rising profits and declining wages. Decline in either has historically been, in most countries, the exception rather than the rule.Only labour works for less than its value. If there were any other source of value, i.e. within exchange itself, then capitalism as a whole could not grow, because for every capitalist who profited with a sale, one would lose out on the purchase.
Debt. Modern economies are financed on credit, which increases investment rates at the cost of diminishing risk/return ratios. The more leverage held, the smaller the decline needed to wipe it out, and since companies and individuals have a general tendency to become more indebted over time, eventually a breaking point is reached where they are wiped out -- then the infamous debt crises occur. The Great Depression was an extreme example of this very basic phenomenon.One question for Aleksei - if you reject a Marxist analysis, what is your explanation for the inevitability of cyclical recessions in capitalism every 5-7 years or so?