RO: Depends on the motive you posit, for one thing. Are you suggesting a firm would reduce prices to raise market share in order to raise profits, either near term or over time (which in either case has enhanced profits as its goal)? Or is market share the goal--because managers prefer the social advantages of a bigger corp.--even at lower profits?
[mbs] Either. In both cases, behavior does not correspond to profit maximization in the short run. I'll leave to you the question of whether Marx's story depends on this or not.
RO: And where does the extra output to serve the larger market come from? Fixed capital (investment) is by definition fixed in the short run. Do they have to hire more (productive) labor, or go to the whip (e.g., "speed-up")? No change in labor, no change in surplus value (depending on the effect of lower prices and more Q on the PxQ calculation that approximates total value). Adding labor to serve a larger market could cut into total surplus value/advanced capital, depending how the numbers worked out (e.g., PxQ).
[mbs] Either.
RO: All in all, an exceedingly minute point, Max. I suppose you could find a corp. that aggressively pursues price cutting to get market share that requires more labor and cuts into surplus value and maybe profits too. And, btw, they could maintain profits by replacing their cronies in the management layers with productiove workers who enhance output. But don't hold your breath. And where are these aggressive, price cutting corps anyway? Nowadays corps get market share mainly by buying it (mergers and acquisitions). . . .
[mbs] My impression is that non-profit-max behavior is ubiquitous, but I'm not prepared to trot out a summary of the empirical I-O lit.
I'll give you another example. Anti-profit maximization via outsourcing. There's evidence of the use of outsourcing for motives other than cost-minimization in the IT field. I got into this because of my interest in privatization. Contracting out is done for reasons other than efficiency or cost, hence it should not be surprising that contracting could end up costing more (ergo less surplus value, I would guess, because these are payments that come out of the firm for purchased inputs).
mbs