<div>I am having some difficulty in the way that the concept of timtum halev is being portrayed. It is as is there is some kind of biochemical reaction effecting a non-corporeal, spiritual entity, the human neshama. The discussion has become bio-mechanistic, e.g.does the consumption of x amount cause it, does bitul do away with it? etc. Where does the intent of the actor come into play? If someone holds be down and forces me to eat a kazayit of treif, does that cause timtum halev, while if I voluntarily consume a minuscule amount it doesn't? </div>
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<div>I would think that maybe the timtum caused by inadvertent consumption (or inadvertent failure to perform a particular mitzva correctly, such as wearing tefilin you didn't know where not kosher) is the fact that the person did not care enough to be careful enough, which, therefore causes a chisaron in his neshama. In this way, one could at least argue that relying on bitul is a permissive but not optimal way to behave, and, therefore can still cause a timtum ( or conversely that it is perfectly legitimate and causes no harm).</div>
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<div>Just my 2 cents.</div>
<div>Shabbat shalom</div>
<div>David I. Cohen</div>