(concurring). I agree with the result and the reasoning of the court, but I add a few words to emphasize that I concur because there was evidence here that the defendant suffered from a mental disease or defect within the meaning of the McHoul rule. In other cases, I have departed from the court’s reasoning where the court, in my opinion, adopted and applied the principle of partial responsibility or diminished capacity where there was no such mental disease or defect. See Commonwealth v. Gould, 380 Mass. 672, 691-693 (1980) (Quirico, J., dissenting, with whom Hennessey, C.J., joins); Commonwealth v. Henson, 394 Mass. 584, 594 (1985) (Hennessey, C.J., concurring). I have expressed particular objection that a defendant’s voluntary ingestion of alcohol or illegal drugs might serve to mitigate or excuse his otherwise criminal conduct. Henson, supra at 594. In this case, although voluntary use of alcohol may have been a precipitating factor, the jury could permissibly find on the evidence that the underlying cause of the defendant’s aberrant conduct was a latent mental disease or defect within the McHoul definition. From that point, it is not unreasonable to put to the jury the issue whether the defendant drank alcohol knowing that it would act, together with his latent disease, to cause his violent conduct. See Commonwealth v. Sheehan, 376 Mass. 765, 769-771 (1978).