In Jain Dharma, the logic is not only “how many जीवs are killed”, but also:

1. What type of जीव is harmed
2. How developed that जीव is
3. How much suffering is caused
4. What intention and involvement the eater has
5. How much violence is directly and indirectly done

So the comparison “one chicken = one jeev, but grains/fruits = many jeevs” is not the full Jain view.

1) A higher-developed जीव is more deeply harmed

In Jainism, all जीव are sacred, but not all violence is equal.

• Chicken, fish, and other animals are trasa जीव — mobile beings with more senses, more awareness, more pain, and more fear.
• Plants, fruits, grains, root vegetables are vanaspati / ekendriya-related plant life — much less developed in consciousness than animals.

So even if a fruit contains many subtle जीवs, harming a more developed sentient being produces heavier हिंसा than harming a less developed one.

2) Pain and fear matter, not just count

Jain ethics looks at the amount of suffering caused.

• A chicken or fish experiences fear, struggle, and pain at the time of capture, slaughter, and processing.
• That suffering is intense and direct.
• With plant food, the जीवs are far less developed, and the violence is generally considered of a different and lesser category.

So the karmic burden is not decided only by arithmetic.

3) Root vegetables are specially avoided

You mentioned onion, potato, garlic, etc. In Jainism, root vegetables are avoided not merely because of “many जीवs,” but because uprooting them destroys the whole plant and harms the life-force in the root and associated living entities.

Why they are restricted:

• The entire plant is destroyed, not just a part.
• Many सूक्ष्म जीव may be disturbed or destroyed.
• Pulling them out usually causes greater हिंसा than plucking a fruit, leaf, or grain in the usual way.

That is why Jain tradition strongly avoids:

• onion
• garlic
• potato
• carrot
• radish
• other underground vegetables

4) Grains and fruits are not treated the same as root vegetables

In Jain thought:

• Fruits can often be taken without destroying the tree.
• Grains are generally harvested after the plant cycle is complete or near completion.
• Root vegetables require uprooting, which is more हिंसा.

So even among plant foods, Jainism distinguishes carefully.

5) Violence in Jainism includes intention

Jain karma is affected by ābhiyog, prayog, and sammārambh — the involvement, intent, and effort in violence.

Eating meat usually involves:

• direct support of slaughter
• demand for killing
• chain of violence through purchase and consumption

So the eater becomes part of the हिंसा.

Plant-based food, especially when chosen carefully, can reduce violence much more.

6) The Jain ideal is to minimize हिंसा as much as possible

Jain Dharma does not say:

• “If something has fewer जीवs, it is automatically better.”

Instead it says:

• choose the least हिंसāful option,
• avoid obvious and intense violence,
• protect all जीव as far as possible.

That is why Jain dietary discipline prefers:

• non-root vegetables
• careful selection of food
• avoidance of meat, fish, eggs, and root vegetables

7) Simple way to understand the logic

Think of it like this:

• Number of जीवs matters
• Type of जीव matters more
• Level of suffering matters even more
• Your intention and participation also matter

So the statement:

> “One chicken = one jeev, but one fruit may contain many jeevs, therefore chicken is okay”

is not Jain logic.

Because in Jainism:

• a chicken is a more developed, mobile, suffering being
• meat-eating involves intense, direct हिंसा
• plant-based food is generally less हिंसाful, even when subtle life is present

8) Final Jain conclusion

The Jain view is:

• Ahimsa is not a counting game
• It is a complete ethic of minimizing harm
• Therefore, Jainism prefers foods and actions that cause the least injury to the most number of जीवs, and especially the least injury to the most developed जीवs

So the logic is not:

• “one life is less than many lives”

Rather, it is:

• “Which choice causes less total हिंसा, less suffering, and less karmic bondage?”

That is why Jainism avoids meat and also avoids root vegetables.

If you want, I can also give you a short, exam-style answer and a longer scripture-based answer in simple Hindi or English.