At least when defining "slavery" as "restricting people to dispose freely of their time, space (or goods…)", and when considering the way most people on Earth are employed today, yes.
Of course, if we define "slavery" as "harsh, senseless, cruel, violent, selfish abuse of other humans", then (I hope in the vast majority of cases), no, contemporary employment and slavery are different in kind.
But I do think there are reasons to doubt this second definition to have been systematically accurate.
For example, it makes no sense, from a cost-effectiveness point of view, for a slave owner to mistreat his slaves that much: it's in his best interest to make sure they live decently. Or, in a society where slavery is culturally acceptable, hence widespread, many slave owners must not have been this inhumane.
I'm not saying it never occurred, merely that there are good reasons to think that it wasn't as systematic as we tend to believe.
I meant in general: I'd expect moderately happy slaves to perform better, and the cost of keeping them moderately happy lower than acquiring new slaves over and over; creating slaves has a cost.
Accurately answering your question requires writing a thesis: one needs extensive access to accurate data spanning thousands of years, a solid grasp of history, psychology, ancient customs, etc. Those situations are full of subtle nuances; what historians currently understand might not even be that accurate.
OTOH, casting reasonable doubts by assuming a fair amount of people weren't too stupid is less bold of a position than "slave owners were living devil", but at least it's honest.
(Which doesn't imply that "slave owners were living devil" isn't true, merely that it's dishonest to say that it's true, because it's too difficult to know for sure).
Slavery is an old thing[0]. Even assuming the death rates are correct, one can't honestly conclude that what happened in the West in the past 500 years is similar to what happened, say, in Antiquity in the West[1] - and that's what most relevant to Aristotle - or amongst ancient Jews[2].
I know that there are too many unknowns for me to even have a clear thesis to begin with.
Are you kidding me? You think the slaves being worked to death in the Roman silver mines or galley ships had it any better than the ones in the New World? Pre-modern slavery was just as brutal.
You seem curiously attached to the happiness in slavery fantasy.
Of course, if we define "slavery" as "harsh, senseless, cruel, violent, selfish abuse of other humans", then (I hope in the vast majority of cases), no, contemporary employment and slavery are different in kind.
But I do think there are reasons to doubt this second definition to have been systematically accurate.
For example, it makes no sense, from a cost-effectiveness point of view, for a slave owner to mistreat his slaves that much: it's in his best interest to make sure they live decently. Or, in a society where slavery is culturally acceptable, hence widespread, many slave owners must not have been this inhumane.
I'm not saying it never occurred, merely that there are good reasons to think that it wasn't as systematic as we tend to believe.