To add to the previous posters:
I’m here addressing what most take to be freewill, agency; roughly: a finite LFW limited by factors beyond any individual’s control, one in part contextualized by a fluid form of causal determinism and in part formed from birth (biologically (and/or karmically for some)) by these same fluid factors of causal determinacy. I take it that most individuals worldwide would agree to something like this as rough description, although evidencing it philosophically is a completely different ball park.
Let’s assume one worst case scenario: the heroin addict once chose to pursue experimentation with heroin despite knowing of all the risks of addiction simply on account of feeling bored with life—as though life itself can ever be deemed boring. (Were the heroin addict to have so become due to extreme psychological or physical pain that was itself not of their choosing, one for which heroin seemed to be the only available remedy, to my mind the scenario of culpability, guilt, would be nowhere near as extreme.)
Even in this worst case, there yet exists the choice on the part of others for things such as forgiveness upon the person’s acknowledgment of having made an error, an understanding born from willingness to step into the other’s shoes, and, consequently, a sympathy—regardless of how mild—via which others attempt to resolve what the heroin addict now recognizes to have been a mistake.
LFW does not apply only to one person, but to everybody. And everybody is fallible—though some will do all they can to deny it, often by placing blame on other(s) for their own doings. In this universally shared fallibility there is the potential for a universally shared forgiveness of imperfections. Not as an encouragement of wrongs but as a—maybe all too idealized—communal effort for mutual assistance to help others out when they are down.
The same becomes far more complex when it is likewise applied to those that intentionally do harm toward others for reasons other than that of self-defense. It is one thing to understand that Charles Manson had an extremely difficult life during his formative years as a child, and to thereby hold sympathy, if not even empathy, for him as a child (something that, from my experiences, unfortunately few people are willing to do). It is an utterly different thing to then deem Charles Manson devoid of culpability for his actions as the adult he became. Notwithstanding, we westerners (or many just those of the USA?) live in a world focused on punishment as retaliation, as communal revenge—this rather than punishment for crimes and misdeeds that is sincerely influenced by motives of successful rehabilitation into society. The former is almost by definition devoid of compassion. The latter almost by definition consists of compassionate forms of realignment to states of moral sanity. But this too is a choice of how to react on the part of those who judge wrongs (as we all always do).
My intend point to all this is that the belief in LFW is not in and of itself something that leads towards less compassion for others. Instead, it is the sense of moral superiority that is, when rationally appraised, bogus which leads to lack of sympathy and empathy for others. For all her imperfections, Mother Teresa would have welcomed helping the heroin addict when she/he asked for help. Whereas your average so called “virtuous person (one that likely believes her/himself to already have a seat in some heaven)” would at best treat such person like lepers not to be touched.
It is true that we all have our limits of inclusion. But while some deal with the us/them divide in terms of absolutes, other’s will address it in terms of degrees, always willing to be more inclusive when they themselves are sufficiently stable in their daily needs.
At any rate, belief in any form of LFW will be belief that LFW is equally applicable to all. There is no grand end of perfect righteousness that anyone of us can obtain in this lifetime (or any other, as the case might be). We all on occasion err. And we all have personal culpability for our errors. From this vantage, we then can choose to assist others in due measure to need, or we can choose to indiscriminately forsake all those who have stumbled while simultaneously declaring ourselves innocent of any “significant” wrong doing … which is bullshit. Our choices today will in part determine what our futures will be; and this applies for every day of our lives.
So no, belief in LFW does not make one less empathetic or sympathetic toward others by comparison to hard determinism. Though it might consist of a somewhat different mindset.
… However, as per William James’ argument, LFW does explain the presence of regret—regretting having chosen this alternative rather than that, something which hard determinism cannot coherently account for. When we don’t succumb to moods of desperation for things we’ve previously done (which is never a good thing for oneself or anyone other we have yet to interact with) our regrets then help us in not repeating the same mistakes ad infinitum, as well as in best remedying the things that are within our control to remedy. Imo, one could well argue that it is the absence of regret which leads to societal mayhem, including lack of sympathy and empathy for others—the rational absence of regret being something that is more in keeping with hard determinism.